Earthquakes can pull massive amounts of carbon into the deepest parts of Earth's deep-sea trenches, scientists have discovered.
After analyzing the offshore magnitude 9 earthquake that devastated Japan in 2011, a team of researchers found that this single event pulled over a million tons of carbon into the Japan Trench to depths of around five miles.
"The results surprised us and our colleagues," Tobias Schwestermann, from the University of Innsbruck, said in a statement. "This is much higher than expected from carbon fluxes observed in other deep-sea trench systems worldwide."
The 2011 earthquake was one of the biggest recorded in recent history. It generated a tsunami that caused widespread devastation to the east coast of Japan—it caused a meltdown at the Fukushima nuclear plant, destroyed 120,000 buildings and killed over 15,000 people. The event was so strong NASA said it could have shifted Earth's axis and shortened our days.
During the earthquake, the Pacific Plate slipped under the plate beneath northern Honshu, along the Japan Trench. In some parts where the fault slipped, the land moved by 100 feet.
As well as causing major changes to the seafloor, the earthquake also caused huge amounts of organic matter to be displaced, with vast quantities being sucked deep into the Japan Trench—a subduction zone that extends down almost five miles.
In a study published in Scientific Reports, scientists were trying to work out just how much organic carbon was pulled into these extreme depths. Quantifying this would allow them to better understand the global carbon cycle—the movement of carbon between fossil fuels, the atmosphere, the oceans and the land.
The team took samples and data that had been collected from the site of the earthquake between 2012 and 2016. They used high-resolution surveys and sub-seafloor structure imaging and then analyzed sediments taken from the site. By looking at the carbon content of the sediments, they were able to estimate the total carbon mass that was transported during the earthquake as being over one million tons.
That this much carbon could be moved during a single earthquake has major global implications, the team say. Concluding, they said that this much carbon is comparable to other Earth system processes, providing a greater insight into how large earthquakes affect carbon cycles. "Taken in the context of estimates of carbon burial in other trench systems, our findings highlight the importance of tectonic events for carbon cycling," they wrote.
Michael Strasser, one of the study authors, added: "The results show that when we talk about the global carbon cycle, we also have to think about the deepest and most-underexplored deep-sea trenches of our world's oceans in the future."
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Hannah Osborne is Nesweek's Science Editor, based in London, UK. Hannah joined Newsweek in 2017 from IBTimes UK. She is ... Read more
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