The Great Chilean Earthquake, the strongest earthquake in recorded history, occurred on May 22, 1960. The main tremors of magnitude 9.5, with an epicenter near the city of Valdivia, lasted for 10 minutes and were felt along the entire Pacific coast. The first series of tremors released 20,000 times more energy than the nuclear bomb dropped on Hiroshima. The earthquake caused a tsunami with waves up to 25 m high, which washed away buildings destroyed by the seismic shocks and claimed the lives of people living on the coast. After some time, the coast was subjected to equally strong aftershocks. Their intensity led to the fact that mountains swayed, sections of roads turned 90 degrees, and river beds changed. The relief of the coast with a length of more than 1000 km was changed – many areas of land sank.
But this was not the end. Mountain landslides that occurred after the earthquake blocked roads and survivors was left without shelter, clean water and food. Mudslides blocked rivers, making the water dirty, mixed with silt and unsuitable for drinking. The situation was aggravated by the large number of people injured during the collapse of buildings. They were treated right on the grass – hospitals were destroyed, doctors lacked medicine. People built temporary houses, but after a few weeks they were forced to leave them – a landslide that blocked the outflow of Riñihue Lake caused flooding on the Valdivia River. Assistance to the earthquake-affected coastal regions of Chile was limited and delivered by air, as all roads were destroyed.
As a result of the Great Chilean earthquake of 1960, more than 6, 000 people died, millions of people were left homeless, and large coastal cities such as Concepcion and Valdivia were completely destroyed. The country’s economy was undermined, and the process of its recovery took several decades. The international community actively involved in providing assistance to the affected population. This was one of the first examples of global solidarity during natural disasters.
What caused the earthquake in Chile
There is tectonic contact between two main lithospheric plates, the continental South American plate and oceanic Nazca plate in the western part of South America. Tectonic plates move, forming a subduction zone, where the Nazca plate slides beneath the South American plate. Friction forces restrain the sliding of lithospheric plates, causing large deformation stresses in the contact zone. Both plates are like compressed springs. And when the stress reaches extreme values, a sharp movement of plates occurs in the rupture zone, which causes earthquakes and volcanic eruptions.
Past and future
Strong earthquakes in subduction zones are periodically repeated, since the mechanical processes associated with the movement of tectonic plates are cyclical. Recent studies by geophysicists have shown that 4,000 years ago, the territory of Chile was already experienced a mega-earthquake with a magnitude of 9.5, and the coast was damaged by a tsunami. Scientists from the University of Chile discovered marine animal remains in the Atacama Desert, which could only get there by a huge wave.
The disaster caused such damage to the region that ancient people left their habitats, climbed several kilometers into the mountains and returned to the coast only 1000 years later. Archaeological research shows that the stone houses of hunter-gatherers were completely destroyed and abandoned 3,800 years ago, although before that the coast had already been inhabited by ancient people for more than 10,000 years.
The released subduction stress of tectonic plates during the 1960 Chile earthquake is gradually accumulating again. One day the cycle will repeat, the region will become seismically active again, and a tsunami will come to the coast. Modern seismologists are actively searching for earthquake prediction methods. The question is partially resolved, scientists know where, but cannot accurately predict when the next mega-earthquake will occur near the coast of Chile.