Journal of Volcanology and Geothermal Research, 44 (1990) 3 4 9 - 386
Elsevier Science Publishers B.V., A m s t e r d a m
349
Erratum
The 1985 Nevado del Ruiz volcano catastrophe:
anatomy and retrospection
BARRY VOIGHT
College of Earth and Mineral Sciences, Penn State University, University Park, PA 16802, U.S.A.
(Received December 1, 1989)
Abstract
Voight, B., 1990. The 1985 Nevado del Ruiz volcano catastrophe: a n a t o m y and retrospection. J. Volcanol. Geotherm. Res., 44:
349 - 386.
This paper seeks to analyze in an objective way the circumstances and events that contributed to the 1985 Nevado del Ruiz
catastrophe, in order to provide useful guidelines for future emergencies. The paper is organized into two principal parts. In the
first part, an Anatomy of the catastrophe is developed as a step-by-step chronicle of events and actions taken by individuals and
organizations during the period November 1984 through November 1985. This chronicle provides the essential background for
the crucial events of November 13. This year-long period is broken down further to emphasize important chapters: the gradual
awareness of the awakening of the volcano; a long period of institutional skepticism reflecting an absence of credibility; the closure
of the credibility gap with the September 11 phreatic eruption, followed by an intensive effort to gird for the worst; and a detailed
account of the day of reckoning. The second part of the paper, Retrospection, examines the numerous complicated factors that
influenced the catastrophic outcome, and attempts to cull a few "lessons from A r m e r o " in order to avoid similar occurrences
in the future.
In a nutshell, the government on the whole acted responsibly but was not willing to bear the economic or political costs of early
evacuation or a false alarm. Science accurately foresaw the hazards but was insufficiently precise to render reliable warning of
the crucial event at the last possible minute. Catastrophe was therefore a calculated risk, and this combination - the limitations
of prediction/detection, the refusal to bear a false alarm and the lack of will to act on the uncertain information available - provided its immediate and most obvious causes. But because the crucial event occurred just two days before the Armero emergencym a n a g e m e n t plan was to be critically examined and improved, the numerous circumstances which delayed progress of emergency
m a n a g e m e n t over the previous year also m a y be said to have contributed to the outcome. Thus the catastrophe was not caused
by technological ineffectiveness or defectiveness, nor by an overwhelming eruption, or by an improbable run of bad luck, but
rather by cumulative h u m a n error - by misjudgment, indecision and bureaucratic shortsightedness. Armero could have produced
no victims, and therein dwells its immense tragedy.
" W e are all of us fellow passengers on the same planet and we are all of us equally responsible for the happiness and well-being
of the world in which we happen to live . . " (Van Loon's Geography).
Introduction
This report begins with Joaquin Acosta's account of tragedy on the Lagunillas; presented
in 1846 in the Comptes Rendus of the Academy
Corrected version of article published in volume 42, pp. 151 - 188.
0377-0273/90/$03.50
© 1990 Elsevier Science Publishers B.V.
of Sciences, Paris, it captures the Colombian
naturalist's observations of a flow of mud that
swept over the site of Armero in 1845:
" A g r e a t s u b t e r r a n e a n n o i s e w a s h e a r d in t h e vicinity o f t h e M a g d a l e n a , f r o m A m b a l e m a to t h e village o f
350
M e n d e z . . . This sudden noise was followed, within a
considerably smaller area, by trembling of the ground.
Then, descending along the Lagunillas from its
sources in the Nevado del Ruiz, came an immense
flood of thick mud which rapidly filled the bed of the
river, covered or swept away the trees and houses,
burying men and animals. The entire population
perished in the upper part and narrower parts of the
Lagunillas valley. In the lower part, several people
were saved by fleeing sideways to the heights; less happily, others were stranded on the summits of small hills
from which it was impossible to save them before they
d i e d . . . On arriving at the plain with great impetus,
the current of mud divided into two branches. The
much larger one followed the course of the Lagunillas
toward the Magdalena; the other, after topping the
high divide, traversed the Santo Domingo v a l l e y . . .
and hurled itself into the Rio Sabandija, which was
thus plugged by an immense dam. The danger seemed
imminent for a flood of downstream lands. Happily,
plentiful rain during the night produced enough water
to begin clearing a passage across this mass of broken
trees, sands, stones, and stinking mud, mixed with
enormous blocks of ice which descended from the
mountains in such abundance that after several days
they had not melted e n t i r e l y . . . The terrain covered
by debris and mud is more than four leagues square;
it presents the appearance of a desert or playa, on the
surface of which loom up like many islands heaps of
broken trees that resisted the impetus of the torrent.
The depth of the mud layer varies greatly, and is much
greater toward the upper part of the deposit where it
often reaches 5 to 6 m. A realistic calculation indicates
more than 300 million tons of muddy material from
the flanks of Volc~in R u i z . . . " *
O f this event, A c o s t a r e m a r k e d in an 1850
letter to the F r e n c h geologist Elie de B e a u m o n t
t h a t all o f the p r o p e r t y w h i c h families h a d acc u m u l a t e d in years o f e f f o r t , the fruit o f l a b o r
o f several g e n e r a t i o n s , was lost in a m u d f l o w
w h i c h d e s t r o y e d h o u s e s , harvests, flocks, a n d
r e n d e r e d the land b a r r e n f o r a great m a n y
years: " I t is a s t o n i s h i n g t h a t n o n e o f the inh a b i t a n t s o f these villages, built o n the
solidified m u d o f old mass m o v e m e n t s , has
even s u s p e c t e d the origin o f this vast terrain,
w h i c h o c c u p i e s an area at least equal to t h a t o f
the p r o v i n c e o f the R h 6 n e , a l t h o u g h ancient
* See Fig. 4 for locations referred to in text.
B.VOIGHT
t r a d i t i o n s testify to the f r e q u e n t m u d f l o w s in
these r e g i o n s . . . "
S u c h ancient t r a d i t i o n s e n c o m p a s s the last
m a j o r e r u p t i o n at Ruiz, k n o w n t h r o u g h the
w o r d s o f P e d r o S i m 6 n , a S p a n i s h priest w h o
c a m e to the N e w K i n g d o m o f G r a n a d a in 1604
( S i m 6 n , 1625; cf. E s p i n o s a , 1986; Velgtsquez et
al., 1986):
"It happened then, that on that day, month and year
[12 March 1595] . . . there came from this volcano
such a loud, hoarse, and extraordinary thunderclap,
and after it three others not so strong, which were
heard within a radius of more than forty leagues . . .
the Spaniards saw that the volcano hurled out a large
amount of pumice, as big as ostrich eggs and from
these down to the size of dove's eggs, sparkling red like
iron from the forge, which resembled erratic stars.
Some fell on them and on their horses, which disquieted them no little. And on the side of this mountain which faced the east . . . the waters of the Rio
Guali, which wets the foundations of Mariquita, it and
its companion which flows in the south, called the Rio
Lagunillas, both originating in the snow which melts
from this mountain, ran so full of ash that it looked
more like a thick soup of cinders than like water. Both
overflowed their channels leaving the land over which
they flowed so devastated that for many years afterward it produced nothing but small weeds . . ."
A r m e r o , which did n o t exist w h e n S i m 6 n a n d
A c o s t a m a d e their j o u r n e y s , was built o n the
site o f these ancient m u d f l o w s . T h e r e f o r e n o
p r e c e d e n t was established w h e n o n the evening
o f N o v e m b e r 13, 1985, N e v a d o del Ruiz ignited
to g e n e r a t e the w o r s t v o l c a n i c m u d f l o w disaster in historic time a n d the s e c o n d w o r s t volcanic disaster o f this c e n t u r y . Its d e a t h toll r a n k s
f o u r t h in history, b e h i n d o n l y T a m b o r a in 1815
(92,000) a n d K r a k a t o a in 1883 (36,000), b o t h in
I n d o n e s i a , a n d M o u n t Pel6e, M a r t i n i q u e , in
1902 (28,000) ( U N D R O , 1986).
S h o r t l y a f t e r 21:00 local time, a relatively
small m a g m a t i c e r u p t i o n at the s u m m i t crater
o f Volcgm Ruiz p r o d u c e d a series o f p y r o c l a s t i c
flows a n d surges that t u r b u l e n t l y s c o u r e d a n d
m e l t e d part o f the s u m m i t ' s s n o w a n d ice cap,
a n d sent t o r r e n t s o f m e l t w a t e r , slush, ice a n d
p y r o c l a s t i c debris in a plexus o f sheet a n d c h a n neled c a s c a d e s over the v o l c a n o flanks (Katsui
T H E N E V A D O DEL R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
et al., 1986). In lower channels the flows
coalesced and entrained debris, vegetation and
ponded water to form lahars, the Javanese
word used internationally to mean a mud or
debris flow of volcanic origin.
On the volcano's fertile western slope, overbank flooding by lahars caused 1,100 fatalities
at Chinchimi, Caldas Province, and destroyed
more than 200 houses and three bridges (E.
Parra P., written commun., 1989). Lahars
feeding the Rio Guali flowed northward and
then east, destroying homes near Mariquita.
Shortly before midnight, in Tolima Province,
successive lahar waves obliterated Armero
(population 29,000), the prime regional
agricultural center. About 5 vertical kilometers
below the summit of Ruiz, Armero became a
crypt sealed in lahar mud (Fig. 1). Over 20,000
were entombed and 5,000 more were injured.
In the vicinity of the volcano, all roads,
bridges, telephone lines, power grids and
aqueducts were damaged or destroyed. Sixty
percent of the region's livestock, thirty percent
351
of its grain sorghum and rice crops, and half a
million bags of coffee were lost. Lahars buried
3,400 hectares of the agricultural land, damaged or eradicated 50 schools and 2 hospitals,
destroyed 5,092 homes, 58 industrial plants
and 343 commercial establishments, and
damaged the National Coffee Research Center
in ChinchinS.. About 7,700 were rendered
homeless. Total damage exceeded a billion
dollars (U.S. AID, written commun., 1986).
Thus "the majestic and silent Nevado del Ruiz,
transformed now to an active volcano, could
not resist singing a hymn of destruction; and
where there was life and hope of production,
there is today an ocean of m u d as mute witness
to the released fury of nature" (Epoca, Dec.
1985).
Yet the eruption was not a surprise, and
neither were its effects. Persistent anomalous
fumarolic, phreatic and seismic activity had
served as precursors for about a year. Colombian workers in hazard assessment and
management were assisted by international ex-
Fig. 1. The town of Armero following the November 13 eruption of Nevado del Ruiz (photo Steve Raymer, courtesy of
National Geographic).
352
~. VOIGHT
pertise. Despite this, the emergency management system failed to avert disaster.
Anatomy of the catastrophe
" T h e n a r r a t o r . . , would have little claim to competence for a task like this, had not chance put him in
the way of gathering much information, and had he
not been, by the force of things, closely involved
• . . This is his justification for playing the part of a
h i s t o r i a n . . . The present narrator has three kinds of
data: first, what he saw himself; secondly, the accounts of other eye witnesses; and lastly, documents
that subsequently came into his hands• He proposes to
draw on these records whenever this seems desirable,
and to employ them as he thinks best•" (Albert
Camus, The Plague)
The awakening
" Y o u must picture the consternation of our little
town, hitherto so tranquil, and now, out of the blue,
shaken to its core, like a quite healthy man who all of
a sudden feels his temperature shoot up and the blood
seething like wildfire in his v e i n s . . . " (Camus)
The Ruiz chronicle begins in November 1984,
when after a century of peaceful dormancy,
earthquakes were felt at the Refugio lodge near
the summit of the mountain and climbers reported unusually strong activity in fumaroles within the summit crater. Three significant earthquakes were felt within 20 - 30 km of the volcano on December 22, one of magnitude 3 - 4, and
over a two-day period, episodes of tremor lasting 5 - 30 minutes were interpreted from records at Chinchin~i (Tomblin, 1985a). At Refugio on December 22, 65 shocks were felt about
every 15 minutes between 17:00 and 22:00 (Hall,
1990-this volume). Snow on Ruiz was covered
with a fine ash and sulfur veneer.
Felt earthquakes and strong fumarolic activity continued into 1985, and on January 6
geologists from the Central Hidro-Electrica de
Caldas (CHEC)visited the summit crater Arenas
and observed that a new, smaller crater had
formed within it. Further investigation led them
to conclude that authorities should "implement
a geophysical and geochemical program for
monitoring a probable eruption" (CHEC unpubl. doc., February 4, 1985; Hall, 1990-this
volume).
In response, a civic committee was formed in
Manizales, a city of 350,000 near Volcfin Ruiz.
With the support of CHEC, regional corporations and local government, its task was "to
form and support a scientific commission to
monitor the volcanic and seismic hazard"
(Hall, 1990-this volume). Colombia's Geology
and Mines Bureau (INGEOMINAS)was then contacted, and on several occasions in the period
February 1 8 - 2 7 geological teams from CHEC
and the University of Caldas, or from JNGEOMINAS, visited Ruiz to investigate its activity. The first articles on the awakening Ruiz appeared in the Manizales newspaper La Patria
on February 21 and 22, and a feature section on
March 3 included the full report of the scientific
commission of the civic committee and photographs of the crater. At Chinchin~i, the only
seismograph that had been operating in the
region broke down on February 23.
John Tomblin, a seismologist from the
United Nations Office of the Disaster Relief
Organisation (UNDRO) at Geneva, was in Colombia in March on another mission. Accompanied by two Swiss seismologists, he investigated Volc~in Ruiz on March 9 at the request of Colombia's civil defense agency
(Defensa Civil) and INGEOMINASand witnessed
a 100- 150-m vapor column above the summit
crater. He concluded that "the abnormal activity at Volc~in Ruiz corresponds to typical
precursory events for an eruption of magnitude". He recommended the immediate installation of a portable seismograph on Ruiz and
noted that INGEOMINAS had the obligation to
conduct monitoring, using international expertise where necessary, and to prepare a hazard
map in anticipation of different types of eruption. The Colombian civil defense was alerted
to its obligation to develop a plan for alarm and
evacuation of the populace in high-risk sectors,
as outlined in an up-to-date UNDRO-UNESCO
T H E N E V A D O DEI R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
H a n d b o o k (1986), on Volcanic Emergency
353
An absence of credibility
Management.
On the surface, INGEOMINASappeared to be in
a reasonable position to prepare a hazard map.
Only three years before, they had published a
48-page report on the glacial and volcanic
geology of the Ruiz - Tolima volcanic complex
(Herd, 1982). Based on a 1974 Ph.D. dissertation at the University of Washington, this study
identified post-glacial lahars and pyroclastic
flows high on the flanks of Ruiz, and established a dated chronology through tephra correlations and radiocarbon dating. The lahars of the
volcanic complex were noted to be " m o r e commonly associated with snow-capped volcanoes", with heat generated by explosive eruptions cited as the cause of rapid melting of ice.
INGEOMINAS had also provided support for
more recent investigations along similar lines
by scientists from Grenoble, France (Thouret
et al., 1985). Although volcanic hazards were
not specifically mentioned, these reports contained detailed soil and tephra columns and
geological maps that included historic lahars of
1595 and 1845, thus providing the basic building blocks for hazard evaluation. However,
these publications were founded on foreign expertise, and INGEOMINAS lacked in-house experience in volcanology.
On March 20, a local conference on volcanic
risk was held at the National University in
Manizales. The participants - many of whom
would later form the nucleus of the Volcanic
Risk Committee - concluded that the possibility of an eruption could not be dismissed, risk
studies were the responsibility of the state,
communities had the right to be informed and
protected, and an emergency evacuation plan
was needed (Calvache et al., 1985). INGEOMINAS Report 1937 on the late February field examination of Ruiz concluded otherwise: "the
volcanic activity can be considered 'normal'
for active volcanoes and does not represent imminent danger." Nevertheless, they advocated
establishment of a monitoring program.
"Please answer me quite frankly. Are you absolutely convinced it's plague?"
" Y o u ' r e stating the problem wrongly. It's not a
question of the term I use; it's a question of t i m e . "
(Camus)
On March 29 in Geneva, Tomblin expressed
his concern in a telephone communique to Dr.
Michio Hashizume, UNESCO Natural Hazards
Unit, Paris (Epoca, Dec. 1985): "nothing is being done about this new activity. It appears that
the University in Bogota does not have volcanic
expertise, and neither does the institute for
geology and mines (INGEOMINAS).That institute
probably carries the responsibility in a volcano
crisis situation." Hashizume subsequently requested G u d m u n d u r Sigvaldason in Iceland,
representing the World Organization of Volcano Observatories (wovo), to nominate a team
of experts in case assistance was requested by
the Colombian government. On April 9, wovo
telegrammed candidates from Costa Rica,
Ecuador and Mexico. The Costa Ricans responded the next day with an offer of three portable seismographs, an electronic tiltmeter and
dry-tilt equipment. In a follow-up letter to
UNESCO on April 15 Sigvaldason expressed his
preference that a four-man team be involved,
including experts from each country. On April
18, Hashizume sent invitations to these individuals with the proviso that the Colombian government formally request their services. Meanwhile, at Volc~n Ruiz, there were 17 felt seismic
events in March, 18 more in April. Sounds interpreted as rock and ice falls were reported
from high in the Rio Azufrado.
On May 4 - 7, Minard Hall, Escuela Polit6cnica Nacional, Ecuador, visited Manizales on
behalf of wovo and UNDROtO evaluate the activity of the volcano and determine what
measures had been initiated to monitor it and
evaluate risk. He reported that "the crater's activity remains stable but in an abnormal state,"
with sulfur salts condensing on summit
354
snowfields. He was concerned that " n o
monitoring activities are being carried out.
Portable seismographs, if they exist, are still in
Bogotfi," and he suggested that local governments might buy then from foreign sources.
" A t least four would be needed" (Hall, 1985,
Spanish version). Hall saw " n o attempt to initiate a volcanic-risk evaluation despite the fact
that good quality maps exist" and stressed the
importance of making a very preliminary risk
map so that Defensa Civil would be better
prepared, especially for damage reaching the
foot of the Cordillera "where larger towns
might be threatened by flowage deposits." He
referred to the Cotopaxi, Ecuador, volcanic
hazard map as an example of what should be
done (Miller et al., 1978), and concluded that
the geothermal department of CHEC was "best
prepared and more interested" in carrying out
hazard mapping and evaluation. INGEOMINAS
administrators in Medellin were aware of the
hazards but "other priorities and the lack of
funds precluded future work there" (Hall,
1990-this volume).
The civil defense of Caldas Province had
meanwhile prepared a disaster plan which appeared to Hall to be "excellent and completely
adequate. However, once the preliminary
hazard map is prepared, it will be necessary to
review the plan and to adjust it in accordance
with the map. It is recommended that the plan
be approved" (Hall, 1985, Spanish version).
He made no mention of a similar plan for the
neighboring Tolima Province in which Armero
lies, although he spoke briefly by phone to the
national director of Defensa Civil. "All groups
were interested" in the possibility of collaborating with a volcanology team sent from
abroad.
On May 30, IN6EOMXNASmade a request to
the U.S. Geological Survey for technical expertise and for geophones and cable needed to
operate in-country seismographs on loan from
Interconexi6n E16ctrica S.A. (ISA). The parts
were provided at UNDRO expense and shipped
by diplomatic pouch on June 26. Informed by
~. VOIGHT
Robert Tilling of USGSthat the INGEOMINASrequest was under consideration (unpublished
correspondence), on June 13, Hashizume looked forward to enrichment of a UNESCO effort
by a cooperating USGSteam. But USGSbranchlevel officials ultimately declined to send a
technical expert, claiming prior commitments
and studies associated with recent eruptions in
Hawaii and Mount St. Helens. On July 2, the
USGSDeputy Chief for Latin America observed
in a note to UNDRO, " T h e opportunity is clear,
and it is unfortunate that we can spare no one
from the Hawaii or Cascades Observatories...
If the volcano is to blow, let us hope that both
we and the Colombians were prepared."
By early July, responding to the perceived
vacuum in hazard evaluation, a Volcanic Risk
Committee (Comit6 de Estudios Vulcan61ogicos C o m m u n i d a d Caldense) had crystallized
from the earlier civic committee in Caldas Province with the support of the regional government, CHEC, the National University in Manizales, the University of Caldas, the coffee and
financial corporations, and concerned citizens
(Medina J., 1986, and oral communications).
This organization was confirmed by government decree in August. The Comit6 initiated
programs for investigation, local risk planning
and public education. On July 7 they acknowledged INGEOMINASfor obtaining seismographs
from ISA, and expressed the futile hope "that
in the next few days INGEOMINASwill turn over
these instruments to our project" (Hall, 1990this volume). The Mayor of Manizales and
Governor of Caldas submitted an official request for technical assistance and equipment to
the Swiss Disaster Relief Corps, and an UNDRO
telex on July 10 to the Swiss Seismological Service supported the Colombian need for assistance in seismic operations and interpretation.
On behalf of the Swiss Disaster Relief Corps
and Swiss Seismological Service, Bruno Martinelli arrived in Manizales on August 8 to assist
Colombian scientists with seismic monitoring.
His equipment included a portable threecomponent short-period event recorder, an
355
T H E N E V A D O DEL R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
MEQ-800 d r u m recorder used as a onec o m p o n e n t continuous monitor to supplement
the event recorder and the INGEOM1NAS network, a one-component system with tape
recorder mostly used to collect data on a
glacier, and Mark geophones (B. Martinelli,
written c o m m u n . , 1988). Martinelli was ably
supported and assisted by CHEC personnel and
by authorities of the Caldas region. He recalls
the following (written communication):
" O n m y arrival, four portable seismographs
operated by personnel coordinated by IN6EOM~NAS were in operation since July 20th in
the region a r o u n d the Nevado. However, they
did provide only little information of relevance
due to their non-optional locations." (They
were relocated in September.) " I t was only at
the end of August, and due mostly to the contribution of Juan Duarte (Instituto de Los
Andes) that the seismic system could be considered to be suitable for monitoring the
volcano at a l l . . . Cooperation between myself
and the persons responsible for the seismic network was always characterized by cordiality
and reciprocal consideration. In particular the
cooperation with Juan Duarte was very intensive and profitable."
The Comit6 and INGEOMINAS were now
operating seismographs independently but the
data were not amalgamated for rapid processing and complete interpretation. The INGEOMINAS data were processed in Bogota.
Although background levels were unknown,
seismic records indicated about 5 - 2 0 countable earthquakes daily, with as m a n y as
4 0 - 5 0 during swarms and occasional tremor
(Cu611ar and Solano, 1985; Fig. 2). M a x i m u m
magnitude was about 3.5 (D. Harlow, oral
c o m m u n . , 1988).
On June 26, the same day that the geophones
were shipped by USGS, the Colombian delegate
to UNESCOwrote to the Minister of Colombian
Foreign Affairs, called attention to the
Tomblin and Hall UNDROreports and noted the
following: "UNESCO has contacted several international organizations and is able to offer
Colombia:
(1) a team of volcanologists from different
countries;
(2) equipment and instruments for measurement;
(3) training for Colombians in their country
or at volcanologic centers of other countries;
(4) exchange of information and experience
concerning similar phenomena. Everything
could be provided in a short t i m e . . . To accomplish this project, it is necessary that the
Colombian government file a formal petition
to UNESCO as soon as possible." Despite this
urgency, the letter was apparently sidetracked.
Nearly two months later it resurfaced, attached
to an August 21 note from an employee of the
Ministry of Education to the Governor of
Caldas Province: " I n this c o m m u n i c a t i o n . . .
the delegate to UNESCO requested that you
should petition UNESCO in order to stop the
reactivation of the volcano (sic) (El Tiempo
Oct. 25, 1985; Epoca, Dec. 1985)." Within a
few days, the letter was in the hands of the
Volcanic Risk Comit6; but by then the volcano
was forging a schedule of its own design.
The credibility gap closes
"(This) marked one might say, the end of the first
period, that of bewildering portents, and the beginning of another, relatively more trying, in which the
perplexity of the early days gradually gave way to
panic.., our townsfolk realized that they had never
dreamed it possible that our little town should be
chosen out for the scene of such grotesque happenings
in this respect they were wrong, and these views
obviously called for revision... And it was then that
fear, and with fear serious reflection, began."
(Camus)
•
.
.
E1 Ruiz c o m m a n d e d attention at 13.30 on
September 11, when a strong phreatic eruption
occurred at the summit crater, lasting for
perhaps 7 hours. It had been preceded by 15minute episodes of tremor every 80 minutes or
so since September 6 (Fig. 2; Harlow et al.,
1986). Violent steam explosions ripped preexisting ash and blocks from the volcano
356
B.VOIGHT
ERUPTION
I
II
I
III 11 II
TREMOR
. I
I
IIIII II
IIIII
I III
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1985
Fig. 2. Volcanic events, seismicevents and energy release at Nevado del Ruiz (data after INGEOMINAS, D. Harlow and
J. Zollweg).
throat, deepening and steepening the walls of
the summit crater (SEAN, 1985; Tomblin,
1985a). Lithic blocks were cast kilometers
from the crater and ash began to rain on
Manizales (Fig. 3) and Chinchin~i, 25 km distant. In mid-afternoon, ice, firn and rock
avalanches were dislodged from the headwall
of the Rio Azufrado, probably reflecting the
combined effect of seismicity and fluid
pressures associated with snowmelt and water
regurgitated from the summit crater. At 18.30
a lahar extended more than 20 km down the
river, eroding through the road link between
Manizales and Murillo (E. Parra P., written
c o m m u n . , 1989). Inhabitants of the valley were
alerted but no evacuations occurred. Martinelli
recalls the situation (written commun., 1988):
" T h e seismic activity prior to the phreatic
eruption of the 1 lth of September was particularly intense and the monitoring seismic
system was operational by this time. However,
this strong activity only started around the
beginning of September. On the 10th of the
same month, at a meeting organized by the
emergency committee at which not only myself
but also INGEOMINAS, the Governor of Caldas
and the Lord Mayor (Alcalde) of Manizales
were present, the seriousness of the situation
was discussed. It was on this occasion that concrete proposals were formulated for a complete
and long-term systematic monitoring of the
volcano, and it seemed to me that all of those
T H E NEVADO DEL RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
357
Fig. 3. Nevado del Ruiz in September 1985, seen from Manizales in Caldas Province. At this time the population was in
a state of "fear, if not panic". The focus on Manizales may have retarded local emergency management in neighboring
Tolima Province, where much greater risk existed (photo Steve Raymer, courtesy of National Geographic).
present were convinced of the necessity of this
course of a c t i o n . . . "
Martinelli expressed concern that the ~NGEOMINAS seismograms were sent to Bogotfi
without being processed; further " T h e danger
of the lahar was not only evident, even to the
layman, but after the eruption of the 1 lth of
September there were no longer any doubts that
some measures must be taken in order to deal
with this danger."
Thus on September 13 the Volcanic Risk
Comit6 in Manizales issued a public warning of
serious risk of additional avalanches of rock
and ice and joined with Defensa Civil and the
Governor of Caldas in recommending evacuation along rivers fed by the snow and ice of Ruiz
(El Espectador, Sept. 13 and 14, 1985). These
statements received considerable media attention although La Patria (Sept. 13) reported on
the front page that "Ruiz activity is not
dangerous" in an attempt to calm the population.
On September 15 the Governor of Caldas
conducted a personal inspection of Ruiz (El
Tiempo, Sept. 18, 1985) and organized a
meeting on September 16 among the governors
of Caldas, Tolima, Risaralda and Quindio and
the Director of INGEOMINAS (El Tiempo and El
Espectador, Sept. 15, 1985). The governors
"agreed that each province would autonomously manage their emergency plans" (La
Patria, Sept. 17, 1985) and appealed to national
government and international experts for assistance (La Patria, Sept. 18, 1985), whereas IN-
358
GEOMINASemphasized the high priority of monitoring (Parra and Cepeda, 1990-this volume). An aviation advisory suggested that pilots should not fly within 50 miles of Ruiz (El
Tiempo, Sept. 17, 1985). On September 18 the
Bogot~ newspaper El Tiempo published a color
photograph of Ruiz on the cover page, and gave
extensive coverage to the developing crisis.
On September 17 t h e ' m a y o r of Armero
reported to authorities that his town was
threatened by a landslide-dammed lake at
Cirpe, 12 km upstream on the Rio Lagunillas
and containing an estimated half million cubic
meters of water, and that flood hazards existed
also on other rivers such as Rio Guali and Rio
Recio, due to geothermally enhanced ice
melting on Ruiz. Regarding the Lagunillas
dam, " a n increase in the volume will bring the
total destruction of Armero. The town has
already had two previous floods with serious
consequences for the population" (La Patria,
Sept. 21, 1985). (Floods occurred in 1935 and
1950 from torrential rains.)
The mayor identified specific barrios bordering the river within Armero to be at risk to
" t r a g e d y " and named an 8-man emergency
committee of civic leaders to request immediate
action from the President of the Republic. The
committee, which included the local chiefs of
Defensa Civiland Red Cross, stated the following (La Patria, Sept. 21, 1985; cf. El Tiempo,
Sept. 18, 1985): " W e are concerned about the
situation created by Volc~m Nevado del Ruiz.
This is unpredictable, but we can see that
critical danger threatens the population. For
this reason we request that the Rio Lagunillas
dam be dealt with, because it represents a time
bomb. The problem of Nevado del Ruiz is well
known to the government and to public opinion, as scientists have issued warnings about
it. For this reason we urge the government to
take the appropriate measures to prevent inundation by the river, as occurred on previous occasions with consequences disastrous to the
population. Today the possibility of a
catastrophe is greater because of 'superpopula-
~ VOIGHT
tion' of the city." The director of Red Cross for
Tolima Province supported this view:
" A r m e r o . . . might disappear if a lahar was
generated on the Lagunillas . . ." (El Tiempo,
Sept. 18, 1985). INGEOMINASconcluded that the
dam, which was not related to volcanic activity,
did not appear to be in danger of failure " u n d e r
normal river conditions"; at the same time, a
drainage plan was recommended but construction was never started (E. Parra P., written
commun., 1989). The actual reservoir volume
at Cirpe was perhaps 250,000 m 3 (R. Janda,
oral commun., 1988).
Meanwhile on September 16, Defensa Civil,
INGEOMINAS, Ministry of Mines, CHEC, Caldas
government officials and coffee-industry representatives met in Bogot~i to consider
emergency plans for Ruiz: " a 25 percent chance
of an eruption was estimated," and Defensa
Civil "declared a state of alert" (El Tiempo,
Sept. 18, 1985).
The September eruption had clearly slammed shut the credibility gap. On September 17, a
meeting of emergency and civil-defense directors convened at the request of the government
to form a national-level emergency committee
to coordinate and plan a response to any further activity on Ruiz (El Tiempo, Sept. 18,
1985; Hall, 1990-this volume; Herd and Comit6, 1986). Defensa Civil developed a management plan and attempted to identify what remained to be done, including procedures to
carry out evacuation. Red Cross assumed
responsibilities for emergency communications and disaster response. INGEOMINAS was
assigned national responsibility for monitoring
and hazard assessment, generally following
UNDRO's time-worn suggestions of March 9.
These agencies met with the Colombian Congress to obtain funding for the work required.
An interparliamentary committee involving the
four provinces influenced by Ruiz was formed
to oversee state aid for scientific work (El
Espectador, Sept. 19, 1985).
A preliminary draft of a volcanic hazard map
was scheduled for October 7 and visual obser-
THE NEVADO DEI RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
vation and monitoring of Ruiz was to be expanded. After September 20, six INGEOMINAS
geologists and four University of Caldas instructors and some students joined forces at a
retreat at Termales del Ruiz, on the flank of the
volcano not far from Manizales, to collaborate
on the construction of the hazard map (Parra
and Cepeda, 1990-this volume). On September
23, before returning to Switzerland, Martinelli
(written commun., 1988) had a chance in
Bogot~i to view a first draft of this hazard map:
"Dario Moschera illustrated to me the criteria
. the danger of lahars, especially along the
Rio Azufrado and Lagunillas, was the guiding
theme of this w o r k . " The Instituto Geogr~ifico
Agustin Codazzi was asked to establish a
geodetic polygon
and
provide
aerial
photographs and maps. A chief of seismology
was drawn from the National University of
Bogota by INGEOMINAS,and regional emergency committees were established to coordinate
local response planning. The existing Volcanic
Risk Comit6 (involving CHEC and regional
universities) in Manizales was assigned responsibility for scientific studies at Ruiz, with input
from 1NGEOMINAS.Nevertheless, on September
24 the Congressional representative for Caldas
"lamented that requests for help sent to 1NGEOMINAS, to Ministry of Foreign Relations
(and o t h e r s ) . . , had not been s u c c e s s f u l . . .
The national government was acting with great
uncertainty" (La Patria, Nov. 17, 1985; Hall,
1990-this volume). In response, the Director of
Defensa Civil emphasized the regional meetings that had been held in July, and the Minister
of Mines and Energy said that scientific and
mitigation studies would be completed "before
the end of October" (La Patria, Sept. 26, 1985;
El Espectador, Sept. 27, 1985; Hall, 1990-this
volume).
Formal petitions for assistance had been sent
to ~JNDRO, UNESCO, USGS and others. In Manizales, "the eruption of the 1 lth September convinced the monitoring committee of the
necessity of immediately having a volcanologist on the spot who possibly had prior know.
.
359
ledge of the Ruiz. The choice did not prove difficult seeing that Franco Barberi had occasion
to work for several months on the Ruiz in 1983
as a consultant to a geothermic c o m p a n y . . , a
member of the monitoring committee made
phone contact with Franco Barberi in Pisa on
September 13th. I also took the opportunity to
inform him of the seismic recordings made, and
it wasn't difficult to convince him of the necessity of his presence in Manizales" (B. Martinelli, written commun., 1988, cf. ¢HEC, 1983).
The Italian team arrived in October.
Meanwhile, the credibility gap had closed
sufficiently for the usGs to release Darrell
Herd, the administrator in Reston who had
studied Ruiz for his Ph.D. dissertation. Supported by the U.S. AID Office for Foreign
Disaster Assistance (OFDA), Herd spent the
week of September 2 0 - 2 7 assisting Colombian scientists in Manizales to evaluate past
eruptions as a basis for future prediction and to
plan investigation programs. On September 23
he gave a public lecture to help dispel what was
then perceived to be "the unnecessarily great
anxiety of the population of Manizales," since
UNI~RO had been informed that the population
was in a state of "fear, if not panic" as a result
of the September 11 eruption (Tomblin,
1985a). El Espectador, Sept. 28, 1985 thus
reported that " a n eruption would only affect
an area within approximately 10 km of the summit."
Manizales was indeed the hub of activity near
Ruiz, being the one large city close to the
volcano. However, Manizales was removed
and in a different province from most of the
main rivers at risk, which flow eastward toward
the Magdalena. In retrospect, this focus on
Manizales may have retarded local emergency
management in neighboring Tolima Province,
where even greater risk existed. This view is sustained by Martinelli (written communication):
"During the whole period of my stay there were
no mutual contacts or cooperation between the
region Caldas, where I was, and Tolima. Only
on September 13th, i.e. after the eruption of
360
September l lth, was a meeting held at the
Defensa Civil in Bogot~i, organized by General
De La Cruz, with representatives of the
authorities of Caldas and Tolima, of the Red
Cross, and the Defensa Civil. As far as I could
see, even after this meeting cooperation between the two regions was insufficient."
A geochemist from New Zealand acquired
fumarole-gas samples between September 22
and 30 (partial analysis revealed significant
SO2) and John Tomblin of UNDRO took over
the advisory role from Herd and Martinelli
from September 25 to October 2. He met with
national leaders of civil defense and ~NGEOM1NAS, participated each evening in scientific and administrative meetings, and reviewed
the work of some local management and
vulnerability-assessment groups. Several hours
each afternoon were spent working on the
hazard maps.
Tomblin (1985a, unpublished correspondence) learned that the seismology network
needed prompt attention. He attempted to acquire radio-linked seismographs to use in shortterm prediction, since the seismograph net
in operation relied for recording on rotating
drums of smoked paper which had to be retrieved every day in the field. Requests were made
by phone and telex to the Volcano Observatory
in Martinique, the University of Paris, the
vsGs, the Swiss Federal Seismology Institute,
the Swiss Disaster Relief Corps and the Swiss
Ambassador in Bogotfi. The problem had not
been resolved by the time of his departure.
Equally important, the Risk Comit6 and INGEOMINAS were still not fully sharing seismic
data. The Comit6 (through Martinelli and
CHEC) had several stations, but an insufficient
number for hypocenter location study. INGEOMINAS had four stations (they added
another on October 23), but data had to be
mailed to the National University of Bogotfi for
interpretation; not only was short-term prediction infeasible, but no seismic data or interpretations were actually issued by INGEOMINAS
until October 7, despite operation of the system
B vo1~nz
since July 20. Martinelli (written commun.,
1988) reported "cordiality" between seismic
specialists from the two groups, but "during
the whole time of my visit I noted a pronounced
rivalry between the emergency committee and
INGEOM1NAS. I was never able to figure out the
reason for this conflict nor to clarify what
responsibilities each institution actually had. In
any case, this rivalry had a strong influence on
the whole phase of emergency preparation."
Tomblin therefore urged closer cooperation
between the two groups in Manizales to permit
all local earthquake data after September 26 to
be interpreted rapidly and as fully as possible,
and through UNESCO,coordinated the return of
Minard Hall from Ecuador to guide the
cooperative effort. He also arranged a mission
by Rudolfo Van der Laat from Costa Rica to
carry out ground-deformation measurements.
In a mission report dated October 9, Tomblin (1985a) noted that eruptions producing
ash-falls and mudflows were more likely than
other types of eruption and observed that "scenarios which should be envisioned for the purpose of hazard zoning and emergency planning
(include) rapid melting of the glacier;" further,
"the area devastated in 1845 has a present-day
population of the order of 20,000." He also
commented that the reactions of scientists and
public safety authorities were greatly stimulated by the September 11 eruption, so that
"'within the very near future, the necessary
measures will have been taken to protect the
population". Martinelli expressed a similar
opinion; though well aware of several obstructions to preparedness, on leaving Manizales on
September 24 he "was convinced that everything would be done to limit the possible damage to a minimum."
Girding for the possibility o f battle
"People in town are getting nervous, that's a fact
• . . And of course all sorts of wild rumors are going
around. The Prefect said to me, 'Take prompt action
if you like, but don't attract attention.' He personally
is convincedthat it's a false alarm." (Camus)
T H E N E V A D O DEL R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
There was general satisfaction that the need
for uniting all available national resources to
meet the volcanic threat was finally recognized.
Political fences had been mended and predisaster planning was at last progressing at a
reasonable pace and in the right direction.
Minard Hall, who returned to Manizales October 2 - 14, set up a hypocenter-location program and assisted in the coordination of
seismic data and the completion of the volcanic
hazard map.
There were still some countercurrents. The
Director of the Geophysical Institute of the
Andes reported in Magazin 8 Dias (Sept. 1985)
that " T o d a y . . . nothing is happening on the
volcano that threatens the i n h a b i t a n t s . . . If it
is necessary to declare an emergency, the Institute will do it. To do so before would only
alarm the populace without reason" (Hall,
1990-this volume). Likewise in Manizales, in
response to conflicting opinions, the Chamber
of Commerce feared that irresponsible reporting "will cause economic losses" and the Archbishop criticized the media for the spread of
"volcanic terrorism" (La Patria, Oct. 4 and 5,
1985). On October 7 La Patria noted in a cover
story that publication of a volcanic-risk map
would cause real estate " d e v a l u a t i o n " (cf. La
Patria, Sept. 18, 1985). Nevertheless, the
preliminary version of the hazard map (scale
1:50,000) was presented in a press conference
on October 7 attended by the Minister of
Mines, the Governor of Caldas (not Tolima?)
and directors of INGEOMINAS, Defensa Civil
and other dignitaries (Fig.4; cf. Parra and
Cepeda, 1990-this volume, fig. 2). " T h e map
showed that extensive a r e a s . . , are threatened
(and) will help various civil defense organizations design plans for e v a c u a t i o n . . , some
cities such as A r m e r o would have 2 hours to
e v a c u a t e . . . " (La Patria, Oct. 8, 1985). But
only ten copies of the map and accompanying
explanation were prepared and distributed
(Hall, 1990-this volume), although INGEOMIhAS staff also met with officials of Armero,
Mariquita and other towns in Caldas and Toli-
361
ma and informed them of the potential hazards
(F. Z a m b r a n o O., cited in Herd and Comit6,
1986). The accompanying INGEOMINAS report
(Cepeda et al., 1985a) referred to lahars as
follows:
"The presence of old mudflow deposits in some river
valleys indicates several possibilities for such events
during a large eruption. The probability for this type
of event is high for the rivers indicated on the hazard
map, and they could occur during any eruption therefore the probability is 100%. The magnitude is
closely related to the size of the eruption and the
availability of water.., for the areas of high hazard
the flow could be 25 m deep, and at curves and narrows
it could reach 50 m."
The report was accurately referred to in
media articles. A generalized version of the
map was published in color on the front page of
the Bogot~i paper El Espectador (though with
some errors in map symbols), and articles mentioned " a 100°70 probability of m u d f l o w s . . .
with great danger for Armero, Mariquita,
Honda, A m b a l e m a and the lower part of the
Rio Chinchin~i" (EI Espectador, Oct. 8, 1985)
and "lahars and floods are i n e v i t a b l e . . .
A r m e r o would be evacuated in two hours
without danger" (El Tiempo, Oct. 8, 1985).
The map was criticized by some government
officials in Bogot~i for "being too alarming"
(Cepeda et al., 1986). The mayor of A r m e r o
stated in a magazine interview that m a n y people in A r m e r o now did not know " w h e t h e r to
stay or leave" and lamented that the local
emergency committee " d i d not have the
necessary information or financial resources to
do anything in the event of a c a t a s t r o p h e . . .
For this reason, the people have lost confidence
in the veracity of the information and have
c o m m e n d e d their fate to G o d " (Consigna,
Nov. 15, 1985; Hall, 1990-this volume).
Meanwhile, Defensa Civil was hard at work
(numerous Defensa Civil documents; P.
Bolton and D. Mileti, written c o m m u n . , 1988):
in September they assembled risk information
by overflights of territory in the hazard zones,
and in late September and October compiled a
362
B. VOIGHT
Vlariquita
Fresno o
\
\
SaOanOlja M
Palestina e
f
Chinchin~.,
4Libano
Lava FlowHazard MudflowHazard
eLerida
PyroclasticFlowHazard
High ~
~
Moderate
. Rio
Ashfall Hazard
High I ~
~
Moderate
Low Angle Blast Hazard
High r-T-'] ~
Moderate
3
t
5
I
'o
I
'5
20 Km. Limit
K omete-~
Ibagu~l
Fig. 4. Volcanic hazard map of Nevado del Ruiz (November 1985version), showing locations referred to in text.
field count of the population at risk along most
major river systems fed by Ruiz. By October 29
the Azufrado and Guali still remained to be
assessed (Defensa Civil documents). Volcanoawareness programs were initiated in schools in
Caldas (El Espectador, Sept. 18, 1985). A
meeting with scientists and Tolima government
representatives on September 30 discussed the
need for "persons with radios in strategic
places along the rivers to help prevent a
catastrophe" (El Espectador, Oct. 1, 1985).
Radio facilities were augmented by fixed and
portable communication devices, and supplies
and equipment such as ambulance tires,
emergency rations, boots and uniforms were
purchased. Defensa Civil representatives of the
provinces at risk met with national officials to
provide regional input for emergency-response
planning, and then conducted meetings with
local officials in Armero, Chinchin~i and Honda to disseminate risk and preparedness infor-
mation. For example, a presentation on " T w o
Natural Catastrophes" was announced for October 1 and 2 in Ibagu6 " t o illustrate to mayors
and other officials in Tolima province the proper response to be followed in the event of a
volcanic catastrophe" (El Espectador, Sept.
30, 1985).
Much of the information transfer to the local
level was coordinated by the emergency committees in each province, which included
representatives from the Governor's office,
Defensa Civil, Red Cross, mGEOMINAS,police,
military, health organizations, and others.
These committees contacted villages to inform
them of the need for preparedness and encourage the development of local evacuation plans.
Defensa Civil volunteers talked directly to local
residents in some risk areas, including village
and riverbank squatters, telling them about
civil defense and the current risks from Ruiz,
and explaining disaster preparedness. One such
THE NEVADO DEL RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
announcement read as follows:
"The Regional Emergency Committee of Caldas
notifies you that in view of the danger that exists due
to melting of snow, which causes mudflows or a rise in
river levels, the margins of the rivers Molinas,
Nereidas, Rioclaro and Chinchin/t MUST BE
EVACUATED and such an EVACUATION must be
accomplished to a minimum height of 50 meters above
the river IMMEDIATELY."
The notifier's name, the notified, the address
and date were also indicated (Defensa Civil
documents).
Some documents suggest an intentional effort to build public confidence in order to
minimize the chances of public panic if a
disaster occurred. P. Bolton and D. Mileti
(written commun., 1988) subsequently found
no evidence that fear was a byproduct of the effort to inform those at risk. In September,
some members of the Bogota legislature had
criticized both INGEOMINASand Defensa Civil
for causing unnecessary fear by their hazard
evaluation and planning efforts (La Patria,
Nov. 17, 1985). But in retrospect, perhaps more
fear would have been desirable at some locations to encourage an appropriate public reaction.
On October 10, in a continuation of Tomblin's quest for equipment, Hall sent the following telex to Robert Tilling, usGs, "Seismic
delay processing 24 hours makes telemetering
desirable." On the 16th, Hall advised UNDRO
by phone that the hazard map had been issued
to government authorities, and that although
seismicity remained abnormal, serious monitoring problems had been encountered (Hall,
1990-this volume).
Also on the 16th, an advisory team representing the National Volcanological Group of Italy arrived in Manizales to advise on eruption
hazards. They reported significant deficiencies
in the monitoring program, particularly with
regard to hypocentral location capability,
telemetry, and semiautomatic data processing
(Barberi et al., 1985): " t o this point in the mission (20 October) we have only the analysis of
363
seismic data on 26 September." They also emphasized the need for a communication system
which could provide immediate alert at the inception of an eruption: "we should consider
that the communication system may be damaged in the initial moments of eruption."
Moreover, "taking in consideration that lahars
are the most dangerous volcanic phenomena
and that there is a great possibility for them to
occur in any type of e r u p t i o n . . , it is advisable
to give high priority to a communication system
that will allow an alert to be rapidly sent to people living in areas exposed to the risk of lahars.
It is necessary to identify a place of refuge in
each of these towns, and to inform the community so that the people will know where to go
in case of an alert." On October 22 the report
was delivered to local government and
emergency managers, and left with the Italian
Ambassador for official transmission to the
government in Bogotfi. By October 31 a complete gas analysis on a Ruiz sample was performed in Italy and the results, which verified
a magmatic origin for the gas, were telexed to
Colombian authorities (Barberi et al., 1986,
1990-this volume).
Between October 21 and November 3, with
support from UNESCO, Van der Laat (1985)
conducted ground deformation monitoring,
though it may be recalled that the Costa Ricans
had been available since April. Although four
dry-tilt stations were established about the
northwest side of the volcano and two electronic
tiltmeters were installed, a retrospective look at
the data "yielded erratic trends not easily
reconciled with even a small intrusion" (Banks
et al., 1990-companion volume); further, "the
electronic-tiltmeter data are not useable
because the tiltmeters were removed nine days
prior to the eruption before settling-in drift had
stopped." The "reliable" dry-tilt data showed
no pre-eruption tilt, perhaps because the source
magma was already emplaced or was too deep
to detect (Banks et al., 1986, 1990-companion
volume). Nevertheless, a consistent tilt pattern
implying deflation emerged from background
364
at one station (SEAN, 1985), and although in
hindsight considered untrustworthy (Banks et
al., 1990-companion volume), " a few days of
tilt observations might have provided unchecked misleading i n f o r m a t i o n " (Barberi et al.,
1986).
On October 29, the Tolima Emergency Committee met for the third time at the Red Cross
office in Ibagu6. The INGEOMINAS representative reported that he and other committee
members had visited 12 municipalities in northern Tolima to provide instructions on volcanic
risk and advice on precautions for the benefit
o f 4,380 residents. Emergency communication
systems were then reviewed by Red Cross and
the hazard map was presented by INGEOMINAS,
along with hazard probabilities. The local
emergency plans of Herveo and Libano were
praised, with the suggestion that these could be
useful models for other municipalities. The
meeting log shows that the Governor's
representative applauded this work and suggested that a meeting be held in Libano to
establish standards and to improve the local
plans in all municipalities at risk. A meeting of
mayors was therefore scheduled at Libano for
N o v e m b e r 15, to be preceded by an organizational meeting on N o v e m b e r 13 in Ibagu6. On
October 30 a telegram from the Governor's representative and a work order signed by the
Governor went to the mayors in each Tolima
municipality within potential reach of Ruiz, informing them that their emergency plans were
to be critically reviewed at the Libano meeting.
Meanwhile, in response to Hall's October 10
telex (but over four months since a plea for
technical assistance had been made by ~NGEOMINAS), the USGS had proposed to OFDA the
installation o f an array of six telemetered
seismographs at Ruiz. OFDA declined support,
and weeks were then lost in interagency
negotiations whether the proposed cost should
be of the order o f $40,00 or $10,000. With the
lower figure finally agreed upon, USGS seismologists Dave Harlow and R a n d y White were
ready to depart on November 7 with a single
B.VOIGHT
telemetered seismograph (D. Harlow, oral
c o m m u n . , 1988). But in a sense symptomatic of
the entire tragedy, the Colombian government
produced other matters o f concern. Already
engulfed in an economic crisis, President
Betancur came under political attack for his
November 6 decision to send troops against
guerrillas who had captured the Palace of
Justice in Bogotfi. The bloody assault left 100
dead, including 11 supreme court justices
(Time, Nov. 25, 1985). Reacting quickly, the
State Department and OVDA concluded not to
send U.S. government employees into a potential hornet's nest; White and Harlow were advised to unpack their bags.
On November 6, most 1NGEOMINASgeologists working on Ruiz left Manizales in order to
complete reports at their home offices in other
provinces (Hall, 1990-this volume). Because of
the Palace of Justice crisis, public presentation
of the revised hazard map (scale 1:100,000) and
report was postponed from November 12 to 15
(Fig. 4; cf. Parra and Cepeda, 1990-this
volume). The November report provided further details on the lahar hazard (Cepeda et al.,
1985b):
"Occurrences of this type of event in these rivers is
extremely high (100070)during eruptive phases of any
type, varying only in magnitude... In the case of an
eruptive event of great proportions (similar to 1845 or
larger in magnitude), the hazard zone has been
evaluated assuming a mud thickness of 50 m over normal river level . . . the maximum assumed thickness
has been calculated on the basis of the measurement of
deposits of mudflows observed in the rivers Guali (at
Santa Ines) and Azufrado-Lagunillas (near Liban).
When the river leaves the canyon, reaching the Rio
Magdalena flood plain, spreading occurs, causing a
thinning and an increase in the area affected. As an example of this, we have the mudflow of 1845, which
near Armero had a thickness of 8 m, with the area of
influence extending to the Rio Sabandija and Rio
Magdalena... In the Rio Chinchinfi are several
rnudflow deposits, and in lower reaches of the confluence of the Rio Claro and Molinas. On this basis,
the hazard zones were delimited with great detail for
the towns of Armero, Honda and Mariquita."
(though not for Chinchin~i).
T H E N E V A D O DEL R U I Z v o [ ( ,\NO C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
The detailed map for Armero implied that
most of the population would have to travel a
distance of over a kilometer in order to reach
the edge of the zone of inundation. The Italian
team had written of the need to identify a place
of safe refuge in each town; but the Armero
map implied that no such simply reached place
existed there and any evacuation therefore
would be a major enterprise.
On November 10, three days of continuous
2 - 3 - H z tremor began at E1 Ruiz. At 78
decibels it was clear but less pronounced than
during the September eruption. Nevertheless,
during a regular meeting of the Comit6 in
Manizales on the 12th, several participants
voiced concern about monitoring and public
education programs (Comit6 Acta No. 24;
Hall, 1990-this volume). No analysis of seismicity had been issued since October 10, and
ISA now wanted their seismographs returned.
Neither ~SAnor 1NGEOMINAScould maintain the
system, and operations were being supported
by the Comit6 and CHEC.INGEOMINASwas asked
to leave them at Ruiz at least until February. On
November 11 INGEOM1NASagain had claimed
that Armero could be evacuated in 2 hours
without danger - ironically, this statement
was published November 14 in El Tiempo.
Day of reckoning
" A picture rose before him of the red glow of the
pyres mirrored in a wine-dark, slumbrous sea, battling
torches whirling sparks across the darkness, and thick
fetid smoke rising toward the watchful sky. Yes, it was
not beyond the bounds of possibility . . . " (Camus)
Nevado del Ruiz erupted with little shortterm warning on November 13, following
almost a year of precursory activity. The rise in
rate of seismic energy released in October and
early November was only slightly larger than
background level, in contrast to the sharp
premonitory increase of energy preceding the
September 11 eruption. Gas samples were collected from summit crater fumaroles on
November 12th but visual observations yielded
365
no signs of impending eruption.
The events of November 13 began in
midafternoon at 15:06 with a phreatic eruption
and its associated seismic signal, lasting about
a quarter of an hour (Harlow et al., 1986). Fine
lithic ash was deposited within a distance of
about 50 km east of the volcano and muddy
rain oxidized metal roofs. Punctuated with
small explosions, tremor then characterized the
seismic record until 21:08.
The regional Red Cross and Defensa Civil offices were soon informed that Ruiz was erupting. Cr. Rafael Perdomo S., Tolima regional
civil-defense coordinator, reported this information to national headquarters and was instructed to warn local Defensa Civil stations
(Fig. 5). Soon afterward, between 17:00 and
19:30, he joined the Regional Emergency Committee for Tolima at their previously scheduled
meeting at the Red Cross office in the provincial capital of Ibagu& The key regional decision
makers were thus already assembled when Red
Cross and Defensa Civil officials reported that
volcanic ash was falling in northern Tolima,
along with heavy rain. Minutes of the meeting
indicate that the police representative was "immediately asked to communicate with central
headquarters in order that telex alerts to
prepare for mudflows and floods might be sent
to all police stations near the rivers Guali,
Azufrado, Lagunillas and Recio." This was accomplished via a hand radio in the presence of
the committee and a similar advisory was
radioed by Red Cross to their municipal stations. In both instances, instructions were
made to " s o u n d the alarm - if necessary - in
the lower reaches of the rivers and at the local
Red Cross headquarters."
The meeting was then officially called to
order, and began with a reading of minutes of
the previous meeting (Defensa Civil documents). Recognizing the possibility of a
developing emergency, discussion first focused
on a suitable location for an operations center.
The police headquarters suited this purpose
because it provided facilities for communica-
366
n, VOIGHT
eruptions
15:06Phreatic
21:08 Plinian
Seismograph
with
Observer
21:10 - 21:37
National Emergency Comite
RING RC NP Army Health Others
Volcanic Risk Comit~
n°tify t°wns] ~ 16:00
of eruption J
21:30
|
|
Regional Emergency Comite" (Tolima)
~ An'ny Health O~'~ers
Other Regional Emergency Comit(~s~B
(Caldas, Rlsaralda, Quindio)
~ ) Others
I
I
Ibagu~ Meeting 17:00-19:30
a
A17.0~r 17:00
T-Ir
it 7
l / °eesary"
?
[15:04 en4~tion]16:00
[flood coming]i
[21:06 eruption]
Murillo 21:45
23:00
~ l g:3C~[ condition]
I
ILnormal J
21:30-22:30
,®®o,
N[~) Health Church Others
Local Comit$s
other towns
Local Emergency Comite (Armero)
[22:30evac;]
, ~
River Observer ~
Radio Armero
18:00-23:00
Priest
I Pub,c
i'21:08 eruption] J
L
18:oo
[be ~lm]
Communication
• OK
(~ Uncertain
O NotOK
l_ibano,Murillo,
22:30 AmbaJema
/
The Public
[becalm]
Caldas
be calm J
Radio
16:00 - Approximate time of communication
[
]
Message
O
Element in communication
DC - Defensa Civil ING - Ingeominas RC - Red Cross NP - Nadonal Police Gov - Governor's Representative
Pres - President's Representative RA - League of Radio Amateurs
SIMPLIFIED
MANAGEMENT SYSTEM AND COMMUNICATION
13 N O V E M B E R 1985
LINKAGES
Fig. 5. Flow diagram of management system and communication linkages for November 13, 1985, emphasizing connections between national, regional and local authorities, volcano observers, and the public. Heavy link lines connect organized groups; thin links connect individual elements such as Defensa Civil offices. Dot symbols indicate effective (OK) or
ineffective communications (not OK), with approximate times and abbreviated messages. Details are given in text.
THE NEVADO DEL RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
tion with remote sites. Following a detailed
discussion, an agenda was then developed for
the forthcoming Libano meeting on November
15. As this meeting was to be inaugurated by
the Governor, preparations needed to be
thorough: it was to include summaries by INGEOMINAS on the hazard map and Defensa
Civil on contingency plans, a videotape on
natural disaster mitigation, a presentation by
each mayor on local emergency plans, a summation of the well-regarded Libano plan and a
forum for the critical review and adjustment of
the local emergency plans. Following this
discussion of the agenda, a census of Los
Nevados National Park (that includes Ruiz)
was presented, restructuring of Emergency
Committee sub-groups was debated and Cr.
P e r d o m o made a presentation "praised for its
clarity" of the Defensa Civil contingency plan
to be presented at Libano. These details are included to demonstrate that the Committee was
not obsessed with the day's events, and indeed
at 19:30, in response to an information request
by Red Cross radio, conditions were reported
to have returned to normal (no ashfall) in
northern Tolima. The meeting concluded with
a reminder of the important Libano meeting.
By about 17:00 the minutes of the Ibagu6
meeting and interview comments suggest that
Red Cross, the police, and Defensa Civil offices
in Armero had all been independently alerted to
the concern of the Emergency Committee (Fig.
5). Local officials were therefore almost certainly aware of the alert, but no formal decision to evacuate had been made. Before 19:30
the abnormal conditions had apparently ended, thus reducing concerns, and in Armero
residents heard repeated reassuring messages
from Radio Armero and the village priest.
At 21:08 a strong eruption-produced seismic
signal occurred within Ruiz and seismographs
were saturated for about an hour. A sequence
of at least four andesitic to dacitic (58-65°7o
SIO2) pumiceous pyroclastic flows (one welded) and two surges were erupted and emplaced
in rapid succession (Calvache, 1986, 1990-
367
companion volume; Janda et al., 1986, 1990this volume; Thouret et al., 1987), as was later
interpreted from the 10-m-thick deposits on the
summit ice cap and the thinner deposits extending several kilometers from the crater (over 5
km down the Rio Azufrado); flow contacts
show several meters of scouring relief. Magma
eruption temperatures exceeded 900°C (Katsui
et al., 1986; W. Melson, oral commun., 1986).
The total dense-rock equivalent volume of
eruption products was 1.9 x 107 m 3
(Calvache, 1990-companion volume).
The flows and surges melted much of the
snowpack and carved a radial pattern of chutes
and channels in the 21-km 2 summit firn and ice
cap and outlet glaciers (Fig. 6; cf. Thouret,
1990-companion volume). Some meltwater
sank into crevasses already choked with
pyroclastic debris, and large slabs of ice, firn
and rock were pried loose from canyon walls
and avalanched into the headwaters of the Rio
Azufrado and the Lagunillas (Pierson et al.,
1990-companion volume). Torrents of meltwater cascaded from the ice cap into the river
channels flanking the cone. By entraining hot
pyroclastic deposits, glacial drift, alluvium and
colluvium, lahars were mobilized in the channels of the major rivers. Campesinas of the upper valleys of the Lagunillas, Molinas, and
Guali reported hearing lahars as early as 21:15
(Pierson et al., 1990-companion volume); initial peak flows were into recession before the
climax of the subplinian eruption column at
21:30 (Fig. 7).
Bernardo Salazar and Rafael Gonzales,
CHEC/Risk Comit6 staff, tending a seismograph 9 km from the crater at El Arbolito had
heard several strong explosions - one of which
"lighted the raincloud over Ruiz like a lamp"
(SEAN, 1985), and Salazar radioed the Risk
Comit6 in Manizales (Fig. 5). Notified by the
Comit6, the Governor of Caldas then called
several commercial radio stations at various
times between 21:30 and 22:30 to issue, in his
own voice, a "red alert" for Caldas communities living along rivers from Ruiz (unpublished
368
~. VOJGHT
Fig. 6. Aerial views of Nevado del Ruiz, before November 13, 1985, left; and after the eruption, right. The Azufrado Canyon borders the crater wall at top right.
correspondence from two Manizales radio stations, Nov. 26, 1985). The information was
passed along to national emergency representatives and to national radio.
The rate o f tephra production peaked at
a b o u t 22:00 and then gradually declined (Carey
et al., 1986). The pumice scorched many roofs
but caused no fatalities. Meanwhile, the lahars
were racing down-valley, growing more
voluminous by scraping a meter or so of rainsoaked colluvium from valley walls, and entraining several meters of bogs, sediment and
pore-water from the valley b o t t o m (Mojica et
al., 1986; Pierson et al., 1990-companion
volume). The mud flowed in surges, " b e c a u s e
where there were bridges the flow would be held
back, and then as soon as it (the bridges)
busted, it started roaring down again" (J.
L o c k w o o d , written communication of eyewitness accounts). Stratigraphic observations
confirmed that the lahars were multi-pulsed
events which were sustained for more than an
hour on the flanks of the volcano, and for more
than 90 minutes further downstream (R. Janda, oral c o m m u n . , 1988). The initial lahar wave
was the most dilute and had the highest peak
stage.
Peak flow depth in all lahar-scoured channels except Nereidas exceeded 10 m. Peak flow
velocities, determined from deposit superelevation at bends, were generally 5 - 1 5 m s -1
(Janda et al., 1986; Rojas and Borrero, 1986;
Lowe et al., 1986; N a r a n j o et al., 1986; Pierson
et al., 1990-companion volume), typical speeds
for lahars on stratovolcano flanks. Subsequent
flow pulses were concentrated with debris,
transporting 2-m-wide blocks, with late pulses
becoming smaller and more dilute. Lahars
from the Molinas and Nereidas gathered with a
peak flow rate about 13,000 m 3 s - 1 , entered
the Rio Chinchin~i, then flowed more than 70
km to the Rio Cauca. The village of Chinchin~i
was struck soon after 22:30; a partial evacuation had taken place, but 1,100 died.* Lahars
* I understand that private interests had given a walkietalkie radio to a campesino well up the canyon from Chinchin~, who did give a radio warning of the lahar. If the
warning was then communicated widely is doubtful (M. L.
Hall, pers. commun., 1990).
369
THE NEVADO DEL RUIZ VO[ CANO CATASTROPHE: ANATOMY AND RETROSPECTION
o+•,•Oo+
i~Man,zales
Mariquita
HondaII
Fresno e
Herveo
SaDandqa
Arbo
oLerida
E•
Pyroc!ast~cDeposit
Actual Mud Flow
C
~
'[E;
'[5 KiIome,e,s
Ibagu6~
\
Fig. 7. Products of November 13 eruption. Contours show thickness of tephra deposit (airfall) [Comit6 data]. Compare
with hazard map.
of the Guali flowed 90 km with a peak rate
about 20,000 m 3 s -1, thinning somewhat
beyond Mariquita before terminating in the
Rio Magdalena (R. Janda, oral commun.,
1988).
A small quantity of muddy flow from the
Lagunillas would ultimately reach the
Magdalena, but upstream matters were more
complicated. The Rio Lagunillas, about 50 km
long from its headwaters on the Nevado to its
debouchment on the Armero plain, is fed by the
Rio Azufrado. Above the confluence, peak
flow on the Lagunillas was about 700 m 3 s - 1
On the 49-km-long Azufrado, however, peak
flow cross-sectional area typically ranged from
2200 to 2600 m 2 (Mojica et al., 1986). With an
average flow rate of roughly 10 m s - 1 (72 km
in 2 hours), discharge averaged about 25,000 30,000 m 3 s - l ; an astonishing peak value of
48,000 m 3 s t occurred about 10 km downstream from the source (Pierson et al., 1990-
companion volume). For comparison, this is
roughly equivalent to the wave produced by the
evulsion of practically the entire reservoir over
the world's largest arch dam in the gigantic
Vai6nt, Italy, landslide catastrophe of 1963.
The Armero story is essentially the Azufrado
story, with the headwaters of the Lagunillas
playing a subdued role. One eyewitness got it
exactly right (J. Lockwood, written commun.,
1988): "the Lagunillas was flowing rather
diminished. It was the Azufrado that brought
everything down and finished the little town
downstream."
At 21:45 to 22:00, officials in Ibagu6, aware
of the paroxysmal eruption, attempted to order
the evacuation of Armero (Fig. 5). Engulfed in
a torrential, ashy rainstorm, Armero experienced power and communication difficulties. By then the Azufrado lahar, 30 - 40 m
high, had rounded the Villahermosa bend and
was but half an hour or so from its confluence
370
with the Lagunillas. The noise of the passing
lahar made it necessary for near-channel
residents to shout to be heard: "it was a
supremely horrifying thing; we thought that
our time had c o m e . . , you couldn't talk to a
person 50 cm away from you because you
couldn't hear" (eyewitness testimony: J.
Lockwood, written commun., 1988). Strong
vibration was felt several kilometers from the
river.
Roughly half an hour after Libano, Murillo
and Ambalema Defensa Civil radios warned
Armero to evacuate (Fig. 5), the lahar broke the
landslide dam at Cirpe and released a coolwater flood wave that raced ahead of the
luminous yellow hot lahar (eyewitness
testimony: J. Lockwood, written commun.,
1988). Time had run out for Armero.
Disgorged at about 27,000 m 3 s - 1 from the
canyon at about 23:30 as a wave nearly 40 m
high (Pierson et al., 1990-companion volume),
the muddy boulder-laden torrent divided into
three branches (Fig. 8). The largest branch
broke from the Lagunillas channel and across
central and southern Armero with a flow depth
of 2 - 5 m and velocities to 8 m s - l , totally
destroying the urban sector, and then generally
following the Rio Viejo - an old Lagunillas
channel - passed Santuario to barely form a
fan in the Rio Magdalena. Another branch
deflected northward and carried a divide to
reach the Rio Sabandija, which it dammed for
hours almost precisely recapitulating
Acosta's 1845 mudflow. A few fortunate survivors were carried on mud the full distance
from Armero to Guayabal. A smaller lahar
descended the Rio Lagunillas. The lahar that
inundated Armero lasted slightly more than 2
hours, but each of its multiple surges lasted less
than an hour (Pierson et al., 1990-companion
volume). A second major pulse struck Armero
at 23:50, followed by half a dozen or more
smaller surges. A final major pulse after 01:00
lasted about 15 minutes (Pierson et al., 1990companion volume).
Many survivors took flight only after hear-
~. VOICHT
ing commotion in the streets as the first flood
waves struck the village. Electric power failed
and confusion reigned in the darkness. Though
many attempted to escape on foot, over twentyone thousand died. Thousands of the injured
managed to reach high ground, but by noon
next day, only 65 of the one to two thousand
residents still trapped alive in the Armero mud
had been rescued. Many experienced great difficulty in extracting themselves from the
viscous mud.
Eyewitness accounts give an insight into the
lack of decisive action, as well as the flavor of
catastrophe (J. Lockwood, written commun.,
1988):
"We witnessed what happened in Armero...
we were in the c i t y . . . t h a t n i g h t at
7:00 in the evening it was raining heavily. We
took shelter in the hotel, had dinner, then the
weather settled down, it got hot. Then a group
of us went out to look for a bar to play billiards
and when we returned at 10:50 the ash started
f a l l i n g . . , we woke the (geology) professor up
and our colleagues, and when the professor saw
that the particles were of lapilli size, he informed us that we should pack because we were leavi n g . . . We didn't hear any kind of alarm,
even when the ash was falling and we were in
the h o t e l . . , we turned on a r a d i o . . , the
mayor was talking and he said not to worry,
that it was a rain of ash, that they had not
reported anything from the Nevado, to stay
calm in our houses. There was a local station
and we were listening to it, when suddenly it
went off the a i r . . , the electric power went
out, and that's when we started hearing the
noise in the air, like something toppling, falling, and we didn't hear anything else, no alarm.
Half an hour before we had been out on the
street and everything was very quiet because no
businesses were o p e n . . , ash had fallen in the
afternoon and they had been informed to stay
home with damp handkerchiefs, that it would
be nothing more than a rain of ash; so there
were no alarms b e f o r e . . , the priest from
Armero had supposedly spoken on a
371
THE NEVADO DEL RUIZ VOI.CANO CATASTROPHE: ANATOMY AND RETROSPECTION
loudspeaker around 6:00 and had said the same
thing, that there was no need to leave Armero,
because the population was alarmed on account of the story about the d a m . . , when we
went out the cars were swaying and running
people d o w n . . , there was total darkness, the
only light provided by c a r s . . , we were running and about to reach the corner when a river
of water came down the s t r e e t s . . , we turned
a r o u n d screaming, toward the hotel, because
already the waters were dragging beds along,
overturning cars, sweeping people a w a y . . .
(we) went back into the hotel, a three-story
building with a terrace, built of cement and
very s t u r d y . . , suddenly I felt blows, and
looking towards the rear of the hotel I saw
(something) like foam, coming down in the
darkness . . . it was (a wall of) m u d approaching the hotel, and sure enough it crashed
against the rear of the hotel and started crushing w a l l s . . , and then the ceiling slab fractured, a n d . . , the entire building was destroyed
and broken into pieces. Since the building was
m a d e of cement, I thought that it would resist,
but it (the bouldery mud) was coming in such an
overwhelming way, like a wall of tractors, razing the city, razing e v e r y t h i n g . . . (then) the
university bus that was in a parking lot next to
the hotel was higher than us (on a wave of
mud), on fire, and it exploded, so I covered my
face thinking, this is where I die a horrible
d e a t h . . , there was a little girl who I thought
was decapitated, but what happened was that
her head was buried in the m u d . . .
A lady told
me, 'look that girl moved a leg.' Then I moved
toward her and m y legs sank into the mud,
which was hot but not burning, and I started to
get the little girl out, but when I saw her hair
was caught, that seemed to me the most unfair
thing in the w o r l d . . . "
"All night long ash was falling. At 4:30 or
5:00, more or less, the noise increased again,
then we thought that another mudflow was
coming, and sure enough, towards the side you
could see something shining that was moving... "
. A n d it started to be light, and that's
"
when we lost control because we saw that horrible sea of mud, which was so gigant i c . . , there were people buried, calling out,
calling for help, and if one tried to go to them,
one would sink into the m u d . . ,
so now you
must start counting time as before A r m e r o and
after A r m e r o . . .
it's like living and being
.
.
Fig. 8. Mudflow deposits of November 13, 1985 near Armero, compared with reconstructed mudflows of 1845 and 1595
(after Mojica et al., 1986).
372
born a g a i n . . , when you analyze that you
realize that a world definitely exists that is
stranger than the normal world in which we
live."
Another witness reported "we were listening
to the radio, but at no time were we told to leave
the town. They simply said to keep cool and remain c a l m . . , perhaps it was the mayor, I'm
not c e r t a i n . . , it was a local station, from
Armero. When we were listening to the radio
we lost the radio wave, and started to tune it
because we thought the radio was broken, but
15 seconds later the lights went out, then we
realized that what happened was that (the mud)
first destroyed the transmitter further
upstream."
Another: "I talked to a young man from the
Red Cross who was caught by the mud and
almost killed, he was very badly wounded. He
said that further upstream there is the
d a m . . , the water that had been dammed
passed by, the mud came behind, and they
realized that the volcano had exploded and
went out to warn the p e o p l e . . . " Similarly,
an official discussing on Red Cross radio the
need to launch a full-scale alarm reported, "the
water is coming!", whereupon the radio went
dead.
Some survivors reported that friends or
relatives had called and urged them to leave.
Their accounts suggest that no systematic,
specific evacuation orders were issued by officials, although in a few cases representatives
of various agencies may have taken action as individuals. Thus one survivor reported (J.
Lockwood, written commun., 1988): " F r o m
Paturri they called at 10:00 at night and one of
the firemen in Armero went out on the streets
blowing a whistle and setting off the alarm,
alerting the people, but the people didn't want
to come out of their houses. They said it was a
lie; because the priest from Armero, the priest
that said the rosary in the afternoon said that
nothing had happened, not to be alarmed."
Similarly, a limited evacuation initiated by Red
Cross in response to events of the afternoon
B. vomnT
"two hours later appeared to be unnecessary
and then became unpleasant because of heavy
rain and nightfall. Consequently, the report of
new explosions at 9:00 that evening, which were
not adequately described as significantly
larger, met with scepticism from local authorities and populations over the need to evacuate"
(Tomblin, 1985b, 1988). Following the late-afternoon ashfall, Radio Armero and the church
public address system had advised calm, and
even by about 23:00, the mayor of Armero, in
ham radio contact with Ibagu6, was sufficiently uncertain of the threat that his family remained in the village. His last words reveal his
surprise: "Wait a minute, 1 think the town is
getting flooded!" (Time, Nov. 25; Tomblin
1985b). A national TV station also had broadcast news of the eruption, although many remember the message as advising no cause for
alarm (P. Bolton and D. Mileti, written communication) - a message appropriate for Manizales but not for Armero. Apparently, Radio
Armero was playing cheerful music when power failed and mud engulfed the station. The inertia of the "be calm" advisories following the
mid-afternoon eruption was apparently not
overcome by subsequent events, and strongly
influenced the crisis decisions of both officials
and the general population.
Aftermath
" E v e n i n g was coming on, but the town, once so
noisy at this hour, was strangely still. The only sounds
were some bugle calls echoing through the air, still
golden with the end of daylight . . . " (Camus)
In the frantic and mournful days that followed, the ranks of the Volcanic Risk Comit6
swelled with volunteer scientists from many nations. The geologic events of November 13 had
yet to be understood, and more important,
danger still existed for perhaps 80,000 people.
More than 90°7o of the ice cap remained on the
Nevado (Thouret et al., 1987, 1990-companion
volume), and although partly armored by
pyroclastic debris, the potential for eruption-
T H F N E V A D O DE[. R U I Z VOI C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
generated mudflows remained high. To aid the
Comit6, the usGs immediately dispatched
(with OFDA support) about ten veteran
volcanologists and mudflow specialists armed
with sophisticated instrumentation. A sixstation telemetered seismic network and a
tiltmeter array were operational by the end of
November (Zollweg et al., 1986; Banks et al.,
1986, 1990-this volume). Because Ruiz was
often obscured by clouds, the telemetered
seismographs provided a first line of defense
for recognizing the onset of new eruptive activity (Decker, 1986).
In addition, the U.S. Department of Defense
sent two C-130 aircraft and 12 helicopters from
the U.S. Army Southern C o m m a n d to assist in
medical evacuation, rescue and hazard missions; four Sikorsky Blackhawks remained until mid-December to fly support missions for
volcano monitoring. For these services, O~DA
was billed by the Department of Defense for the
phenomenal amount of $2,124,000: DOD thereby claimed 78% of the total assistance provided
by the U.S. government. Yet the need was real,
since Ruiz reached above the elevation
capability of other helicopters in service in Colombia. Underscoring this fact, a Colombian
helicopter vanished without a trace over Ruiz
later that month, and several crashes have occurred.
Recognizing the need for a second line of
defense to ensure that no lethal mudflow could
occur without a public alert, Risk Comit6 chief
Pablo Medina and R.J. Janda in December and
January tried to gain USGS/OFDAapproval for a
critically-located 7-station lahar-warning network with GOES satellite telemetry, technology
that had been demonstrated at Mount St.
Helens. However, USGSincluded overhead and
placed a cost of $290,000 on the project, and
the proposal was rejected by OFDA on the
grounds of cost and technical complexity. OFDA, in fact, was anxious to disengage from
operations at Ruiz. It remained for the Japanese Ministry of Construction, in February, to
provide two ground-telemetered, multiple-ca-
373
ble lahar detectors. Detector location was based on accessibility and line power, with receivers at ovc, Manizales (Rio Molinos) and the
police station at Villahermosa (Rio Guali) containing an audio alarm and paper printout indicating which cables have broken and at what
time. In October 1988 two additional stations
were installed on the Rio Azufrado and the Rio
Recio. The station locations do not allow appreciable lead time for some villages, and the
need remains for near-source monitors on all
major rivers fed by Ruiz.
On the evening of January 3, vigorous
seismicity began at 23:20, saturating seismographs within an hour (SEAN, 1985). LOWfrequency tremor began to dominate the
seismic records at 01:28 (January 4), accompanied by B-type earthquakes and explosion
events. Initially, the summit was not visible,
but ashfall was noted at 03:00. Evacuation of
about 15,000 residents from valleys of major
rivers began at 06:00. It took more than 3 hours
to make the necessary decisions and pass the
alert to the public, 4:32 hours if reckoned from
the onset of low-frequency tremor, 6:40 hours
from the onset of strong seismicity - times far
in excess of that required for a lahar to reach
endangered communities. Fortunately, tephra
production was minor and no hazardous lahars
were generated by this event; unfortunately,
the circumstance was regarded as a false alarm
and thereby influenced future hazard decisions
(Fig. 9).
Since November 13, worrisome signs of instability in the thin septum separating the crater
from the Azufrado headwall had raised the
possibility of a catastrophic rock fall and lateral
blast. EDM-monitoring, however, proved the
wall to be stable and not an immediate threat to
the population below (Voight, 1986; Voight et
al., 1986, 1987).
By February 1986, the Risk Comit6 had
evolved into a well-equipped Observatorio
Vulcanol6gico de Colombia (ovc) under INGEOMINAS, with constructively phased-out support by vsGs and OFDA.
B.VOIGHT
374
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EVACUATION DECISION AND COMMUNICATION CHAIN
POST 13 NOVEMBER 1985
Fig. 9. Evacuation decision and communication chain in January 1986. Decision-making was not efficient for the minor
eruption of January 3 - 4 , 1986; fortunately, no mudflows reached populated areas.
R e t r o s p e c t i o n
"In this respect our townsfolk were like everybody
else, wrapped up in themselves.., they disbelieved in
catastrophes. A catastrophe isn't a thing made to
man's measure; therefore we tell ourselves that it is a
mere bogy of the mind, a bad dream that will pass
away. But it doesn't always pass away and, from one
bad dream to another, it is men who pass away
• . . because they haven't taken their precautions."
(Camus)
B e f o r e a t t e m p t i n g to c o n s i d e r the f a c t o r s
that specifically c o n t r i b u t e d to c a t a s t r o p h e at
Ruiz, let us t a k e a step b a c k to l o o k over s o m e
problems of volcanic-hazard management.
O n e p r e d i c a m e n t illustrated by D e c k e r a n d
D e c k e r (1981) mimics o n a larger scale the
J a n u a r y 1986 event at Ruiz:
"In 1976, a small eruption of La Soufri6re on
Guadaloupe led to a massive and expensive evacuation
of 74,000 residents because of the threat that the eruption might climax in catastrophic nu6es ardentes
similar to those of the Mont Pel6e eruption on the
neighboring island of Martinique in 1902. Fortunately, no major eruption took place; but unfortunately,
volcanologists were blamed for their 'cry wolf'
forecast."
V o l c a n i c e m e r g e n c y m a n a g e m e n t is faced
with a s e l d o m - w i n situation. W h a t does one cry
o u t w h e n t h e r e m a y be a w o l f ? (Decker a n d
D e c k e r , 1981). T h e v o l c a n o l o g i s t ' s p r o b l e m is
to r e c o r d a c c u r a t e l y the probabilistic c h a n c e o f
THE NEVADO DEL RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
error in event forecasting and hazard delineation, and yet maintain the specificity and
credibility necessary to encourage appropriate
government and management action, and
public acceptance and response to the message.
At the same time, predictive capability and
risk assessment are only the first stage in the
complicated process of volcanic-hazard management. To illustrate, three models are shown,
all relatively simple but each successively more
involved. In the most elementary model, volcanic-risk assessments are directed toward government authorities, who then have the option
to develop policy and to create a management
structure capable of responding to the perceived hazard (Fig. 10a). Unfortunately, the window of meaningful communication opens infrequently between the scientists, who prognosticate d o o m on a crude probabilistic basis,
and the pragmatic decision makers. In the opinion o f one experienced observer of the
political scene (Hess, 1987):
"Scientists are generally viewed with less regard
than any other group on the Hill. From my observations, they are perceived as people who don't understand the system, who have little ability to talk with people outside their profession, and who think that being
correct is always enough . . . (Scientists) must learn
that budgets, limited time frames, regulatory impacts,
and public accountability are all factors that must be
considered by Congress. Scientificfacts are not the only criteria in public decision making."
A result is that government may choose not
to employ emergency management.
Yet an adequate emergency plan and critical
risk levels must be established before an adequate response can be expected to result from
geophysical warnings. Further, if the public is
to respond appropriately, they need to be convinced that the threat is real, they may need to
believe that they personally are at risk, and they
need to know precisely what to do and where to
go (Perry et al., 1981). Some of these elements
were apparently missing at Mount St. Helens,
when the public ignored restricted zones and
exerted pressure to have restrictions removed,
375
and when political interests influenced
restricted-zone boundaries (Saarinen and Sell,
1985).
An event which possesses the form, if not the
substance, o f danger may therefore be a prerequisite for attracting the proper attention of
government officials, of the population-atlarge and even of hazard assessment organizations. Anxiety in sufficient quantity and properly distributed is a proven catalyst to action.
Thus the prime precursor event triggers action,
not only among risk evaluators but also among
stakeholders, as seen in the second model.
Stakeholders are those who are exposed to
direct or indirect losses or mitigation costs from
a hazardous event - the property owners, the
non-risktaking cost bearers, financial institutions, local, state and federal policy makers,
and the planners and insurers (Petak and
Atkisson, 1982). Stakeholders wield political
clout. Just as a lightning discharge in the
uprushing ash column creates an electromagnetic surge, so the prime precursor
event closes, if only momentarily, the credibility gap separating stakeholders from risk
evaluators (Fig. 10b). With the gap closed, risk
communication occurs and stakeholders are
activated. Pried by the stakeholders, a window
to influence policy opens momentarily for the
risk evaluators, and a management structure is
spawned to deal with future events.
With the onset of a damaging and perhaps
lethal event, existing management structure is
tested, as seen in the third model (Fig. 10c). The
schedule of decision making may be influenced
by risk communication, but that mechanism is
part of the management plan. Management is
"successful" if the consequences of the event
are minimal, although the vicissitudes of fortune may ultimately decide the outcome.
Viewed in this light, the efforts at Ruiz in early 1985 may be represented by the simplest
model. Risk evaluations by UNDRO specialists
found an audience - of sorts. But apart from
the preliminary disaster plan unveiled by
Defensa Civil in May, progress was sluggish
376
B. VOIGHT
and uncoordinated. INGEOMINAS did not yet
appear fully committed to the task, in part owing to a lack of personnel experienced in volcanology, and probably also from a lack of
conviction that the threat was real. Thus (B.
Martinelli, written commun., 1988): "the
directors of INGEOMINASalways saw the situation of Nevado del Ruiz as a temporary
emergency. Thus they openly opposed the creation of a permanent observatory in Manizales,
preferring to concentrate all monitoring activities in Bogot&" Perhaps also lacking con-
viction, and possibly unwilling to act without
OFDA funding, usGs administrators were willing to part with seismic transducers from supply stock (for which they were reimbursed) but
were not motivated to release specialists in
volcanic emergency management or seismology. In any event, with the perception of a vacuum of responsibility at the national level, it was
necessary for citizens and industry at a regional
level, within the shadow of the volcano, to
gather a Comit6 to consider systematic monitoring and risk planning. Under such circum-
a.
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MODELS
OF P O L I C Y - M A N A G E M E N T - C O N S E Q U E N C E
RELATIONSHIPS
Fig. 10. Three models of policy-management-consequence relationships, each successively more involved. Events at
Nevado del Ruiz progressed from the simplest model (a) in early 1985, to model (b) when the September 11 eruption served
as a prime precursor event that closed the credibility gap, and finally to model (c) on November 13, 1985.
THE NEVADO DEI RUIZ VOLCANO C A T A S T R O P H E : ANATOMY AND RETROSPECTION
stances a rivalry between the Comit6 and INGEOMINAS seems understandable.
The volcanic hazard map requested by
Tomblin in March and urged by Hall in early
May still had not been prepared by September,
and consequently management plans then in
existence lacked the necessary focus toward
areas targeted for high risk. The relative efficiency of UNESCO's early response had been
checkmated, lacking a formal petition from the
Bogota government.
With the September 11 eruption of Ruiz as
the prime precursor event, Colombia moved into the realm of the second model. The gap of
credibility closed, opening the doors to centralized power in Bogot& A National Emergency Committee emerged to coordinate activities,
~NGEOMINASbecame energized to take seriously
and to complete the hazard map, and various
regional committees accelerated their efforts.
Responses to Colombian requests for assistance were facilitated by enhanced credibility
and the technical support essential to hazard
management was provided by a flow of international expertise.
By October, the management structure appeared to be relatively effective but when put to
the test a month later - as in the third model
- the system failed.
Of the numerous factors that played a role in
the catastrophe, the following may be underscored:
(1) Power failures and communications
breakdowns are c o m m o n as a direct or indirect
result of volcanic eruptions; indeed they were
anticipated. Communications problems reported at Ruiz included the failure of repeated latehour attempts to convey an evacuation message
directly from Ibagu6 Defensa Civil to Armero
Defensa Civil and the failure of an upstream
observer on the Lagunillas to directly contact
Defensa Civilin Armero by transmitting radio.
However, review of technological communications for November 13 reveals that the
system contained many redundant elements
and on the whole worked successfully (Fig. 5).
377
By 17:00 representatives of Defensa Civil, Red
Cross and National Police, all fixtures in
Armero emergency management, had been independently alerted and were told to sound the
alarm if necessary. Information about the
" e n d of abnormal conditions" at 19:30 was
also received, although it certainly produced a
signal contradictory to the succeeding alert.
Messages concerning the evening magmatic
eruption arrived by various sources, including
commercial radio beginning 21:30 to 22:30,
which remained available for messages from
regional or national authorities, and Defensa
Civil radio from at least three localities after
22:30. River observers' information probably
influenced evacuation suggestions to Armero
from Libano, Murillo and Ambalema (El
Tiempo, Dec. 4, 1985); thus the basic message
ofDefensa Civilhad gotten through, at least indirectly, by about 22:30. Red Cross radio from
Armero to Ibagu6 was also connected, probably before 23:00. Though the timing of many
of the messages was probably too late to avert
casualties, numerous lives could have been saved had prompt action been taken.
It appears that the catastrophe cannot be
primarily attributed to technical breakdowns in
communications, which had succeeded in providing sufficient if imperfect information. The
primary pro01em was one of intent and value;
that is, the lack of will to act decisively.
(2) Response to an evacuation alarm issued
immediately after the onset of the afternoon
phreatic eruption would have enabled no lives
to be lost, although by itself this event produced no long-reaching lahars, and thus could have
provoked a charge of "false alarm". An alarm
at the onset of the magmatic eruption would
also have provided enough time for a wellprepared Armero population to escape with little loss - the two hours of lead time that had
been forecast by INGEOMINASproved correct provided that the given alarm and public
response were swift, and the possibility of a
false alarm was accepted. Nevertheless, at
Chinchin~i where the Governor of Caldas gave
378
the alarm as early as 21:30, casualties were high
and perhaps inevitable due to the realities of inefficient response and the much shorter lead
time for Chinchin~i.
(3) The scientists, emergency managers and
particularly the local officials therefore had
their backs to the wall. The risks were known
early and well enough, but provincial and national government made the conscious decision
not to evacuate the villages unless and until the
precise moment that danger could be guaranteed. To evacuate before the event, especially
for an indefinite period, would have caused
enormous problems and political risks for a
financially strapped government in providing
the funding, facilities and resources needed to
support a transported community. Security
against looting in evacuated areas, and even the
possibility of insurgents taking advantage of
crisis conditions, could not be overlooked. And
on the whole, the population would have
resented leaving their homes and having their
livelihood and comfort disrupted; lacking a
paroxysmal event, criticism surely would have
been severe. Therefore, fearing both the
economic and political cost, no official was
willing to take the responsibility for the order
unless the damaging event - for Armero a
long-reaching lahar, not merely an eruption could be predicted with almost absolute certainty. For science - whether the scientists actually recognized it or not - it became more a
matter of detection than of prediction.
Thus, the authorities on the whole acted not
unreasonably but were unwilling to bear the
economic or political costs of early evacuation
or a false alarm. Science accurately foresaw the
hazards but was insufficiently precise to render
reliable warning of a devastating event at the
last possible minute. Therefore, catastrophe
had to be accepted as a calculated risk, and this
combination - the limitations of prediction/detection, the refusal to accept a false
alarm and the lack of will to act on the uncertain information available - provided the immediate and most obvious cause of catastrophe.
B. VOIGHT
(4) The local authorities were poorly prepared, funded and equipped to respond to an
emergency. In some respects, deficiencies at
this level could be attributed to the delays inherent in the entire chain of information flow.
The last links of the chain were at the village
level. With earlier essential links of the process
much delayed, time for critical review at the
village level was minimized. Although the ample attention given to the evacuation possibility
in mid-September could have encouraged adequate preparations and development of sound
decision criteria, progress in Armero may have
been contradicted by government attempts to
allay local fears of the Cirpe landslide dam.
Also, detailed hazard mapping implied the lack
of any safe, easily reached refuge - thus any
decision to evacuate implied a major logistical
undertaking. In mid-October the mayor lamented the state of frustration and confusion
after the hazard map had been released - and
noted a loss of "confidence in the veracity of
information"; clearly he needed help. One may
surmise that some progress had been made in
preparation for the November 15 Libano
meeting, but it was too late.
(5) Preliminary evacuation plans for Armero
were drawn up by the local emergency committee, but apparently not many individuals had
yet seen them. " W h a t - t o - d o " information had
not yet been meaningfully communicated to
the population and the people were thus not
adequately prepared to act either individually
or with official instructions.
(6) The response of civil defense was initially
hampered by the lack of specific hazard information and maps, although Defensa Civil had
a rather complete regional plan for volcanicrisk management on paper by early May.
Although progress was also restrained by the
lack of cooperation between provinces facing
similar hazard, these plans were re-evaluated
and modified after September 11 and the process of adjustment accelerated after October 7.
Nevertheless, it is one thing to have a plan on
paper, and another matter to implement it.
T H E N E V A D O DEL R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
Although the need was clearly recognized, local
plans had not yet been critically reviewed nor
proof-tested by warning and evacuation drills
to identify and correct weak links in the system.
(7) Preparation of hazard maps was not timely. Under ideal emergency-management circumstances the month-long lead time might
have been adequate; but at Ruiz the delay in
producing the hazards maps impeded the
mitigation effort, particularly for sites such as
Armero and Chinchin~t where detailed local
maps were essential for the completion and
refinement of local management plans and for
educating local decision makers and the
population on the specific nature of the lahar
threat. In addition, other agencies' concern
over the map as an obvious missing link
diverted attention from additional points of
weakness in the mitigation chain. When released in October, the preliminary map and explanation were poorly distributed and the revised map was not released until November 14, the
day after the catastrophe.
(8) Key individuals with specialized knowledge can bring a hazard-assessment group
rapidly up-to-speed regarding key outcrops,
observations and local conditions, and can
significantly reduce the time required for
preliminary hazard evaluation and effective
monitoring. It is vital that such individuals whether or not skilled in volcanic emergency
management - enter the hazard-evaluation
picture as early as possible; but nonColombians most experienced in Ruiz geology
were not available until, in one case, after
September 20, for the second individual October 16 and for a third only after November
13. In part this may reflect bureaucratic sluggishness or the reluctance of administrators in
such agencies as usGs and OFDA to release personnel or provide pre-disaster support for
foreign assignments. In any case, this factor
contributed to the delays in production of the
Ruiz hazard maps and in effective monitoring.
(9) Proclamation of the "end of abnormal
conditions" after 19:30 caused confusion and
379
skepticism, inasmuch as it conflicted with
alerts concerning the evening magmatic eruption. This factor - which might be classified as
" b a d luck" - possibly impeded more decisive
action by authorities in Armero and created
conflicting media advisories that retarded
public response to sporadic evacuation suggestions. Similarly, darkness and storm made conditions more difficult.
(10) What of the role of technology in the
catastrophe? Would telemetered seismographs
and real-time analysis have prevented disaster?
The seismic records indicate that the 15:06
phreatic eruption of November 13 was preceded by an energy release only slightly larger than
background level, in contrast to the clear
premonitory increase prior to September l l .
Following the November phreatic eruption,
both earthquake activity and harmonic tremor
amplitudes increased abruptly, and tremor frequency decreased, suggesting to some experts
that a very short-term warning "might have
been possible" for the 21:08 eruption; further,
"cumulative tremor energies may have been a
better short-term predictor (i.e. a few days)
than earthquakes for the November 13 eruption, since an episode of low-level tremor began
on November 10 and continued until the eruption onset" (J. Zollweg and D. Harlow, written
c o m m u n . , 1986; cf. Gil et al., 1987; Muf~oz et
al., 1987). But Zollweg (written commun.,
1988) has since concluded after comprehensive
examination of the records that neither
cumulative earthquake energies, tremor
energies, nor low-frequency earthquake or
tremor patterns would have been recognized as
short-term precursors prior to November 13:
" T h e depressing conclusion is that all shortterm precursors of seismic nature were amb i g u o u s . . . Your conclusion is correct regarding the lack of seismic contribution to the
c a t a s t r o p h e . . , in this case there was to be virtually no recognisable short-term warning."
However, to partially offset the lack of
telemetry, a seismometer 9 km from the crater
was manned and had direct communication
380
B. VOIGHT
with Manizales (as recommended by the Italian
team), and indeed the eruptive event was
detected and reported with time sufficient to
save most lives if appropriate action had
followed. The deficiencies of the seismograph
network, however real, did not contribute to
the N o v e m b e r catastrophe.
And what o f the lahar detectors? These were
not an off-the-shelf item, and - perhaps surprisingly - their utility was not widely
recognized until A r m e r o was destroyed. Even
then they were rejected by OFDA. While the required lead time for assembly, installation and
resolution of problems in the development and
maintenance of communication linkages
would have provided a hurdle to the effective
use of detectors before N o v e m b e r 13, since
then it has been abundantly clear that detectors
are essential for ensuring that no damaging
lahar can occur without an adequate public
alert. The cost seems small when viewed as insurance. The detector system installed by the
Japanese currently plays an important role,
although near-source monitors are still lacking
to provide sufficient lead time for all communities at risk.
Lessons f r o m A rmero
"Apparently it came to this: we might try to explain
the phenomenon . . . but, above all, should try to
learn what it had to teach us . . ." (Camus)
When Andr6 Coyne's magnificent but illfated dam in southern France failed in 1954 and
the resulting flood erased much o f the town o f
Frejus, the limit o f the state-of-the-art design
o f arch dams was reached. An important lesson
that emerged from this disaster was that
drainage is necessary to reduce hydrostatic
pressure downstream o f thin arch dams: the
state-of-the-art o f dam engineering was
thereby advanced. Are there similar lessons to
be gained from Armero? Or are there no new
lessons to advance volcanic emergency
management - merely an underscoring or
reinforcement o f lessons already compensated
by past catastrophes?
Hindsight, while o f no value to the former
residents of Armero, can be of benefit if it helps
to avoid similar occurrences in the future. In
this respect, Volc~in Ruiz offers a better type example of current hazard management than
M o u n t St. Helens, for lessons derived from
Ruiz are more easily exported to other
dangerous volcanic regions, the majority o f
which are located in developing countries.
In the 20th century at Armero, twenty thousand - a b o u t 70% of the population - died in
a virtual repetition of an event which killed
about one thousand - roughly 70% of the
population - in the 19th century. In comparison, at M a y o n volcano in the Philippines,
where 1,200 died by surge and m u d f l o w in the
1800s, the current population in the zone o f
high risk approaches 800,000. Population
growth demands that people continue to live in
areas o f high hazard, many o f which are places
of considerable agricultural and economic
value, and as a result, natural catastrophes of
the future can be expected to be of staggering
proportions. It is therefore imperative that the
developed countries pool financial and technological resources to establish programs that emphasize pre-disaster preparedness in order to
cope with such expected extreme-magnitude
crises.
(1) At Ruiz, it was not so much the imprecision of science, or inept last-minute decisionmaking, or breakdowns of a few communication systems at the vital moment - the failure
was to wait until the last possible minute. One
cannot expect emergency management to
operate efficiently at that time scale; but this is
often what h u m a n nature seems to demand. It
seems less a matter of excessive confidence or
false sense o f security than the lack o f will to act
in the face o f uncertainty and the unwillingness
to accept the costs implied by the finite probability of a false alarm. Given that natural
human tendency, the developed nations must,
on the one hand, continue to improve event
prediction, event detection and communica-
T H E N E V A D O DEL R U I Z V O L C A N O C A T A S T R O P H E : A N A T O M Y A N D R E T R O S P E C T I O N
tions technology for early warning, and urge
drills with the population at risk; but at the
same time, they must also seek to improve
education in facing uncertainty and false
alarms, and seek to achieve improved understanding of policy science, so that rationally
conceived public policies are brought to bear on
these difficult problems in order that the expectations of crisis management might be reduced
to a reasonable level.
(2) In moments of crisis, complex decisionmaking processes that rely on a chain of command, hours of committee discussion and the
assumption of unstressed communication linkages, are neither efficient nor effective. The
decision-making process can be much simplified by advance consideration of decision
criteria. In countries with a highly centralized
government, there is a tendency for officials to
fear taking the initiative without higher
authorization; consequently, a village leader
may wait too long to initiate the emergency action required to stave-off disaster. A documented proviso authorizing provincial and
local action in time of known volcanic crisis
might be a feasible mechanism to surmount this
difficulty.
(3) The communication chain is no stronger
that its weakest link: in emergency planning of
this sort, it is often the final links that are the
weakest but the most important, yet problems
in local emergency response are reported in
disaster case histories time after time. Management's efforts tend to concentrate on the earlier
links in the planning process, with less vigor
and critical review applied as succeeding links
and more local problems are encountered. In
the future, specific attention should be given to
local problems at an appropriate early stage.
Parallel rather than series communication
linkages may offer time-saving advantages
(Fig. 9).
The final link, that of providing timely, simple and effective information to the public can
be aided by news media, but they have neither
the exclusive nor the prime responsibility. Civil
381
authorities must decide upon and implement
direct and convincing measures to prepare and
alert the population. This information must
convey respect for emergency measures and a
specific sense of what-to-do for individuals
who may lack the capacity to read and write.
When given, the warning must convince the
public to act. For example, evacuation research
shows that sirens, even when preceded by
public education, are insufficient to persuade
people to leave their homes; sirens must be
backed-up by repeated verbal (possibly taperecorded) warnings from a respected public official (Perry et al., 1981; Mileti et al., 1986).
(4) Radio-communication problems are
endemic in the steep canyons and dissected terrains of volcanic country, and these are exacerbated by the meteorological conditions which
accompany eruptions. Communications technology for crisis response needs thorough
evaluation. Satellite telemetry, microwave
telephone systems, standby power sources, and
redundancy all have a place in volcano
emergency management.
Yet electrical systems are susceptible to
lightning damage, and require trained technicians and the availability of electronic parts
to keep them functional. Consequently, crude
traditional communications systems in current
use should not be totally abandoned and
replaced by their high-technology counterparts; they should be employed as a redundant
system. With an appropriate population
distribution, for example, a linkage of individuals drumming on hollow logs, passing
the message from one community to the next "head for high ground N O W " - may be more
effective in an electrical ashstorm at dead of
night than a plan assuming an orderly response
to a radioed alert.
(5) Hazard maps play a crucial role, yet one
might question whether the precise map boundary, or the precise contour defined in these
maps, should make much difference to
preliminary planning. In the future, when a
volcanic-hazard specialist is called to a crisis
382
situation in a country lacking such expertise,
part of his mission should be devoted to the
rapid production of a preliminary hazard map,
however crude, from the materials available to
him. Whereas he may advise the host country's
geological bureau of its obligation to conduct
investigations needed to improve and field-test
the map, the first priority is to produce a timely
document-in-hand that will allow mitigation
planning to proceed without further delay.
Clearly, individuals known to possess special
knowledge of the volcano should be sought out
immediately and included in early efforts to
evaluate hazard and produce maps.
But at the same time, the utility of hazard
maps should not be overemphasized. The production and media publication of a hazard map
is not synonymous with risk communication.
Indeed, the map itself, such a familiar tool to a
scientist, planner or engineer, may be virtually
incomprehensible to individuals unfamiliar
with the abstraction of reality on a sheet of
paper. Conventional education is no guarantee
of the ability to comprehend a map, a problem
that becomes more acute as one moves down
the communication chain, since the literacy of
individuals at risk cannot be assumed.
(6) The response at Ruiz underscores the
need for risk assessment, baseline monitoring
data, reliable prediction and detection
technologies, and the development and proof
testing of alarm systems and evacuation plans
in advance of volcanic crisis. Inasmuch as the
majority of the world's high-risk volcanoes are
in developing nations, scientific and economic
support must be derived largely from developed nations and international organizations.
Most existing programs for so-called rapid
crisis assistance are ad hoc in nature; they are
inefficient and not truly rapid. A modest step in
the right direction is the Volcanic Early-Warning Disaster Assistance Program (VDAP), recently developed by USGSand OFDAto fOCUSon
South and Central America (Banks, 1986). It
includes such desirable features as development of scientific-political liaisons to avoid ad-
B. VO[GHT
ministrative hurdles and to facilitate rapid entry in time of crisis, an experienced technical
core team capable of rapid response and a stateof-the-art equipment cache. However at the
time of writing, the VOAPcache still lacked an
off-the-shelf lahar-monitoring capability. Other problems have surfaced because of bureaucratic inertia. Support agencies still do not inevitably appreciate the necessity for baseline
observational studies; these may be castigated
as "research" and too often are not considered
as justified under pre-crisis conditions. Thus
current efforts are helpful, but they are inadequate to address the problem on a global scale
(Tilling, 1989). There is an urgent need to develop, strengthen and expand such long-term programs until developing nations acquire self sufficiency in volcanology.
(7) Finally, it is significant that such a small
eruption at Ruiz was able to cause such a
tremendous loss of life. Less than 5 × 106 m 3
of magma ejected as pyroclastic flows was able
to generate about 6 × 107 m 3 of lahar deposits
from 1 to 2 × 107 m 3 melt water (Calvache,
1990-companion volume; Pierson et al., 1990companion volume). It had been known that
such events could occur from eruptions on
snow-covered volcanoes; at Mount St. Helens
in 1982, for example, a blast of hot pumice and
gas caused a lahar with peak discharge about
14,000 m 3 s -1 (Waitt et al., 1983), and in
South America a spectacular and wellpublicized lahar was produced by eruptiontriggered snowmelt at Cotopaxi volcano,
Ecuador, in 1877 (Wolf, 1878). Nevertheless,
Ruiz provides a particularly poignant reminder
of the special sensitivity of the snow-capped
volcanoes to even minor volcanic events.
Epilogue
"Summoned to give evidence.., he has exercised
the restraintthat behoovesa conscientiouswitness. All
the same, followingthe dictates of his heart, he has
deliberatelytaken the victim's side . . ." (Camus)
At Ruiz, most of the elements considered
THE NEVADO DEL RUIZ VOLCANO CATASTROPHE: ANATOMY AND RETROSPECTION
highly desirable for successful volcanic emergency management were in place. The surficial
stratigraphy surrounding the cone had been investigated to USGS "Cascade Range" standards, a geochronology had been established
and post-glacial pyroclastic flows and lahars
had been mapped. Accurate and perspicacious
reports of key historical events were on record.
Advice was available through able and experienced foreign specialists in volcanic emergency management, and monitoring equipment was provided. Many Colombians worked
admirably and knowledgeably, and the consequences of a potential eruption were adequately foreseen by risk evaluators. A hazard map
was produced over a month before the crucial
event, and the problem had registered significant concern among national, provincial and
local governments, despite inevitable credibility issues that arose from time to time. The
magmatic eruption turned out to be small, and
its effects were not unprecedented - in fact the
historical data provided extremely close
analogies. Unlike Coyne's dam in southern
France, no startling issues arose to shift the
course of events. A n d yet in the end, time proved to be a luxury squandered.
The catastrophe was not produced by technological ineffectiveness or defectiveness, nor
by an overwhelming eruption o f unprecedented
character, nor by an improbable run of bad
luck. Armero was caused, purely and simply,
by cumulative h u m a n error - by misjudgment, indecision and bureaucratic shortsightedness. In the end, the authorities were unwilling to bear the economic or political costs of
early evacuation or a false alarm, and they
delayed action to the last possible minute.
Catastrophe was the calculated risk, and nature
cast the die. And so the lessons from Armero
are not new lessons; they are old lessons forged
in human behavior that once again require the
force of catastrophe to drive them home.
Armero could have produced no victims, and
therein dwells its immense tragedy.
383
" A n d it was in the midst of shouts rolling against the
terrace wall in massive waves that waxed in volume
and duration, while cataracts of colored fire fell
thicker through the d a r k n e s s . . , that [it was] resolved
to compile this c h r o n i c l e . . . [to] bear witness in favor
of these plague-stricken people, so that some
memorial of the injustice and outrage done them
might endure; and to state quite simply what we learn
in a time of catastrophe: that there are more things to
admire in men than to despise." (Camus)
Acknowledgements
In Colombia I worked as a member of the
Comit6
de
Estudios
Volcanol6gicos,
Manizales, with support of OFDA and coordination by tJSGS. Although drawing heavily
on the work of the Comit6, I accept full blame
for the interpretations and opinions expressed
here. If there is value to this report it is due to
the generosity of the numerous individuals who
provided critical but unpublished documentation, newspaper articles and personal insights,
and who were also willing to correct erroneous
or misleading statements in earlier drafts. I
therefore particularly thank the following for
contributions of information, manuscript
review, or photographs: P. Bolton, M.L.
Calvache, H. Cepeda, R. Decker, T. Ertekin,
J.C. Griffiths, M. Hall, D. Harlow, R.J. Janda, B. Martinelli, H.J. Meyer, D. Mileti. F.
Parra, T. Pierson, B.A. Shattuck, J.C. Thouret, J. Tomblin, E.G. Williams, S. Williams, K.
Young, and J. Zollweg. I also owe a great deal
to Jefe P. Medina J., and the entire Comit6
staff; OVTRAndinistas M.L. Calvache and O.
Ospina H.; F. Zambrano O. and A. Nunez, INGEOMINAS; N. Banks and the USGScrew; acting
U.S. Ambassador J.P. Osterling; and A. Swan
and staff, OFDA. Translations were provided
by J. Lockwood, C. Faria, A. Lacazette, R.
Holcomb, and particularly C. Moy. Finally,
but hardly least, I wish to express my gratitude
to Judith Kiusalaas for her enthusiastic, skillful
and unflagging efforts to disguise my deficiencies in logical thought and muddled attempts to
384
properly render the English language. Some
material in this paper was presented at the 1986
Lahar and Landslide Workshop in the Philippines, and Institutes for Disaster Prevention in
Tsukuba and Shinjo, Japan. A preliminary
version was delivered to the 1988 Ruiz Volcano
Workshop in Manizales, and a non-referenced
version was published by Penn State University
(Voight, 1988).
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