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Topics: Science, World News
Daisy Phillipson
A new study has discovered history’s largest earthquake caused a 5,000 mile wide tsunami, wreaking havoc on the planet 3,800 years ago.
With a magnitude of around 9.5, the natural disaster is believed to have started in northern Chile, generating a tectonic plate rupture so huge, it lifted the coastline.
Scientists also discovered evidence to suggest the tsunami reached over 5,000 miles to New Zealand where boulders, some the size of cars, were sent inland.
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Professor James Goff of the University of Southampton, who co-authored the study, said: “It had been thought that there could not be an event of that size in the north of the country simply because you could not get a long enough rupture.
“But we have now found evidence of a rupture that’s about one thousand kilometres long just off the Atacama Desert coast and that is massive.”
The researchers, led by Professor Diego Salazar at the University of Chile, came to the conclusion that a tsunami followed after discovering sea sediments and creatures so far away from the coast.
“The Atacama Desert is one of the driest, most hostile environments in the world and finding evidence of tsunamis there has always been difficult,” added Professor Goff.
“However, we found evidence of marine sediments and a lot of beasties that would have been living quietly in the sea before being thrown inland. And we found all these very high up and a long way inland so it could not have been a storm that put them there.”
The event would have had a devastating impact on the hunter-gatherer communities living in the Atacama Desert at the time.
“The local population there were left with nothing,” noted Goff.
“Our archaeological work found that a huge social upheaval followed as communities moved inland beyond the reach of tsunamis.”
He continued, “It was over 1000 years before people returned to live at the coast again which is an amazing length of time given that they relied on the sea for food. It is likely that traditions handed down from generation to generation bolstered this resilient behaviour, although we will never know for sure.
“This is the oldest example we have found in the Southern Hemisphere where an earthquake and tsunami had such a catastrophic impact on people’s lives, there is much to learn from this.”
Prior to this study, published in Science Advances, Goff had been looking into a site on Chatham Island in New Zealand and why gigantic boulders had been thrown hundreds of metres inland at around the same time as the earthquake in Chile.
Oddly enough, he was then asked to join Professor Salazar’s team by chance to investigate the sites in Chile, and they put two and two together.
“In New Zealand we said that those boulders could only have been moved by a tsunami from northern Chile and it would need to be something like a 9.5 magnitude earthquake to generate it,” he added. “And now we have found it.”
The scientists hope to use the findings to understand more about natural disasters in the Pacific region, with Goff concluding: “While this had a major impact on people in Chile, the South Pacific islands were uninhabited when they took a pummelling from the tsunami 3800 years ago.
“But they are all well-populated now, and many are popular tourist destinations, so when such an event occurs next time the consequences could be catastrophic unless we learn from these findings.”
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