Experts identify giant tsunami that decimated coastal communities for 1,000 years


A terrible earthquake triggered a giant tsunami that wreaked so much havoc on the inhabitants of the coast that it took them at least 1,000 years to return to live on the shore.

Geologists and archaeologists who say we must learn from past earthquakes worry that modern authorities have not considered how much worse the next earthquake will be and must adapt their plans accordingly.

They discovered that life changed dramatically 3,800 years ago when northern Chile was hit by devastating tremors and tsunamis that surpassed perhaps the most powerful earthquake ever recorded to date. today.

The strongest seismic event known to science is the 1960 earthquake that struck the town of Lumaco, near the city of Valdivia, located approximately 744 kilometers from the Chilean capital, Santiago. The earthquake registered 9.4 to 9.6 on the moment magnitude scale.

The quake and resulting tsunami caused thousands of deaths and up to $3.5 billion to $7 billion in damage, adjusted for inflation.

Ships and sailors were lost, Valdivia was devastated, and farmland sank in some areas by at least two meters, becoming permanently flooded.

The resulting waves reaching 10.5 meters (34.4 feet) hit Hawaii, China, Japan and the Philippines.

But a multidisciplinary study in the journal Science Advances suggests that a similar earthquake occurred not far away in northern Chile, but thousands of years ago, registering a magnitude of 9.5.

Co-authors Diego Salazar, Gabriel Easton and James Goff discovered that the ancient earthquake was a killer that drove people inland, where they remained for 1,000 years.

Stone walls of ancient dwellings in Chile have been destroyed and found under tsunami deposits.

Some walls have overturned towards the ocean, probably due to the devastating undertow of the wave.

Samples of shells, sea life and sea rocks were washed inland in Chile and found on land four to seven meters above current sea level.

And on the other side of the world, in New Zealand, a giant wave generated by the ancient earthquake even threw rocks the size of cars hundreds of meters inland.

Easton said: “Their formation cannot be explained by global changes in sea level.” He added that ancient clashes of the Nazca and South American tectonic plates were the cause.

Chileans have learned to live with certain seismic events, but even they would be shocked by the ancient devastation geologists and archaeologists uncovered.

An international team led by Chilean researchers in Spain published their discovery of a massive, life-changing earthquake in the Atacama Desert 3,800 years ago in Science Advances on April 6.
Departamento de Geologia – University of Chile/Zenger

The authors noted that there was evidence “that there was a mega earthquake in the past, which altered the settlement and connection to territories on the part of ancient coastal communities in the north of the country” .

Shifting tectonic plates and the tsunami of 3,800 years ago caused waves 15 to 20 meters (50 to 65 feet) above sea level in parts of Antofagasta, Atacama and from Tarapaca, on the coast north of Santiago.

Tectonic plates are huge sections of the Earth’s surface that rub against each other, rupture and cause volcanic eruptions and earthquakes.

The longer the rupture lasts, the greater the earthquake.

Because the Atacama region is one of the driest in the world, it is difficult to find evidence of tsunamis.

Goff said, “However, we found evidence of marine sediments and many beasts that would have lived quietly in the sea before being cast inland.”

He added: “And we found all of these very high and very far inland, so it couldn’t have been a storm that put them there.

Easton said: “For that, ‘something’ has to lift it and we assume that ‘something’ is the tectonic upheaval that occurs in large subduction earthquakes.”

Salazar said: “Our hypothesis is that this event could have generated very high mortality among people, or it could also have motivated the migration of a significant number of people to other territories.”

The ancient mega-quake caused a sea change in coastal communities for hundreds of miles, while the few survivors abandoned the coastline.

He said: “In the next thousand years, the population seems to recover as cemeteries reappear, sites are larger and more numerous, suggesting that demography is beginning to recover. But settlements and cemeteries place them at a higher altitude and a greater distance from the coast than before the event.”

A terrible earthquake triggered a giant tsunami that wreaked so much havoc on the inhabitants of the coast that it took them at least 1,000 years to return to live on the shore.

Easton found a seismic crack inland, showing archaeological evidence that it happened almost 4,000 years ago, resembling a similar crack caused by a nearby 1995 earthquake.

The authors believe the study can guide preparations for future disasters.

They suggest that the death of so many people thousands of years ago meant that even the knowledge of how to adapt to life in earthquake zones – which is still a challenge today – was lost. .

Salazar pointed out, “If knowledge is not constantly cultivated and reactivated, it begins to become diluted.”

The study noted that current disaster planning is based on data dating back only to the 19th century.

Given the new information and the possibility of earthquakes at least as large as the one in 1960, this means, according to Salazar, that “management plans must be calibrated against this possibility, with a view to reducing the risk of catastrophe associated with this type of event”.

Highlighting the danger the earthquakes pose to people living elsewhere, Goff said: “Although it had a major impact on the people of Chile, the South Pacific islands were uninhabited when hit by the tsunami. 3800 years ago.

“But they are all well populated now, and many are popular tourist destinations, so when something like this happens the next time, the consequences could be catastrophic unless we learn from these findings.”

This story was provided to Newsweek by Zenger News.

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