It could put 140 million lives at risk.
The biggest earthquakes on Earth — including the Indian Ocean quake and tsunami in 2004, and the Tohoku quake and tsunami off Japan that caused the Fukushima nuclear disaster in 2011 — have all occurred along subduction zones, where one tectonic plate slowly thrusts under another.
Until now, all known subduction zones have occurred under the ocean. However, researchers report in the journal Nature Geoscience that subduction is currently taking place below Bangladesh, and it represents an “unprecedented hazard in one of the most densely populated regions of the world.”
"Some of us have long suspected this hazard, but we didn't have the data and a model," said lead author Michael Steckler, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory, in a press release. "Now we have the data and a model, and we can estimate the size."
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Strain has been steadily building between the plates for at least 400 years and could culminate in a quake of up to 9.0 in magnitude, rivalling the largest known modern quakes, according to the researchers
"We don't know how long it will take to build up steam, because we don't know how long it was since the last one," he said. We can't say it's imminent or another 500 years. But we can definitely see it building."
The newly identified zone is an extension of a much larger seismically active region. According to the release, a giant tectonic plate has been thrusting northeasterly into Asia for tens of millions of years. This collision is what caused the Himalayas to form, and has given rise to events like the 2015 Nepal quake that killed 8,000 people.
Study co-author Syed Humayun Akhter, a geologist at Dhaka University in Bangladesh says that the country is unprepared for a massive earthquake. "Bangladesh is overpopulated everywhere," he said.
"All the natural gas fields, heavy industries and electric power plants are located close to potential earthquakes, and they are likely to be destroyed. In Dhaka, the catastrophic picture will be beyond our imagination, and could even lead to abandonment of the city."
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