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Evidence of the strongest earthquake in human history

A 9.5-magnitude earthquake followed by a devastating tsunami may have struck northern Chile 3,800 years ago.

To date, the largest earthquake ever recorded occurred in 1960 in Valdivia, southern Chile, with a magnitude of 9.4, killing about 6,000 people and dragging a tsunami across the Pacific Ocean. The crack that caused the Valdivia earthquake was very large, extending up to 800 km.

However, new research published in the journal Science Advances in April revealed that an even more powerful ancient super-earthquake, estimated at 9.5 magnitude, may have ravaged northern Chile thousands of years ago, stemming from a 1,000-foot rift. kilometer. The event created tsunami waves 20 meters high and about 8,000 kilometers long that hit New Zealand, where it swept car-sized rocks hundreds of miles inland.

Simulation of a 20 m high tsunami caused by a super earthquake.  Photo: Live Science

Simulation of a 20 m high tsunami caused by a super earthquake. Image: Live Science

Like the great Valdivia disaster, an ancient superquake occurred when one of the Earth’s tectonic plates was forced up or down by another. The two plates are then blocked by friction, but the force causing the collision continues to form. Eventually, so much tension builds up, that the point of contact between the plates separates, forming a giant crack that releases energy in the form of seismic waves.

Evidence for ancient superquakes has been found in marine and coastal materials – including coastal sediments, rocks, shells and marine remains – that researchers have discovered have moved into the depths inland in the Atacama Desert of Chile.

“We found evidence of marine sediments and the remains of a lot of marine life being swept inland. It’s all very high above sea level and a very long way inland. , so there can’t be any storms strong enough to get them there,” said geologist James Goff at Britain’s University of Southampton, lead author of the study.

Goff and his colleagues used radiocarbon dating to date 17 deposits at seven separate excavation sites on 600 kilometers of Chile’s northern coast and found these coastal materials. was washed inland 3,800 years ago.

The team also presented another piece of evidence for an ancient super-earthquake and tsunami involving stone structures built by the ancients. They found walls buried under sediment, some of which were pushed back, suggesting they were toppled by the strong currents of the tsunami.

“The locals there were left with nothing. Our archaeological work found that a great social upheaval occurred after coastal communities moved inland, out of reach. The impact of the tsunami. It took more than 1,000 years for people to return to live on the coast, which is an amazing time because they rely on the sea to feed,” Goff added.

As this is the oldest known discovery in the Southern Hemisphere of an earthquake and tsunami that devastated human life, researchers are eager to further explore the area. They believe the new discoveries can provide better predictions about the potential risk of future super-earthquake events.

Doan Duong (According to Live Science)

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