A new study has found evidence that the largest earthquake in history may have been a magnitude 9.5 Chilean earthquake that occurred nearly four millennia ago.
Researchers from Chile, the United Kingdom, Australia and France say that this earthquake occurred 3,800 years ago in the Atacama Desert, located in present-day northern Chile, and caused created tsunamis that affected coasts as far away as New Zealand and possibly Japan.
The results have been published in a peer-reviewed journal Scientists progress earlier this month.
According to the study, the strength of the ancient earthquake rivals that of 1960 in Valdivia, located in southern Chile.
The Valdivia earthquake was estimated to have a magnitude between 9.4 and 9.6, making it the strongest earthquake on record. However, this earthquake had an 800 kilometer long rupture. This newly discovered earthquake in the Atacama Desert is estimated to have extended 1,000 kilometers.
“We had thought there couldn’t be an event of this magnitude in the north of the country simply because we couldn’t get a break long enough,” said study co-author James Goff. and visiting professor at the University of Southampton, in a press release. “But we have now found evidence of a rupture about 1,000 kilometers long just off the coast of the Atacama Desert and which is massive.”
Researchers found extensive coastal rock deposits inland, indicating evidence of a massive tsunami. They also found ocean sediments, as well as remains of marine life believed to have been swept into the desert by a tsunami.
“The Atacama Desert is one of the driest and most hostile environments in the world and finding evidence of tsunamis there has always been difficult,” Goff said in the statement.
“However, we found evidence of marine sediments and many beasts that would have lived quietly in the sea before being cast inland. And we found all of these things high up and very far inland. land, so it couldn’t have been a storm that put them there,” he added.
Researchers say the earthquake and subsequent tsunami caused “exceptional social disruption” to the hunter-gatherer-fisher societies that lived there at the time.
“The local people there have nothing left,” Goff said. “Our archaeological work revealed that enormous social upheaval ensued as communities moved inland, out of the reach of the tsunamis.”
Goff said people from the Atacama Desert didn’t return to the coast until more than a thousand years after the quake.
“It’s likely that traditions passed down from generation to generation have reinforced this resilient behavior, although we’ll never know for sure,” he said.
Across the South Pacific Ocean, researchers have also found evidence in New Zealand that the tsunami threw rocks the size of cars hundreds of meters inland.
“In New Zealand, we said these rocks could only have been moved by a tsunami from northern Chile and it would take something like a magnitude 9.5 earthquake to generate it. And now we found it,” Goff said.
The researchers hope their findings will lead to a better understanding of the impacts of extreme earthquakes and highlight the importance of learning how to build a resilient society in the face of such natural disasters.
“This is the oldest example we’ve found in the Southern Hemisphere where an earthquake and tsunami had such a catastrophic impact on people’s lives, there’s a lot to learn from this,” Goff said. . “When such an event occurs the next time, the consequences could be catastrophic unless we learn from these findings.”