How did the Chile earthquake happen?

Answer 1

Chile is on the western coast of the continent of South America, this is the boundary between two tectonic plates, the Nazca plate (which is an oceanic plate) and the South American plate (a continental crustal plate).

In this region the Nazca plate is moving eastwards towards the South American plate. The dense oceanic crust of the Nazca plate is being forced under or subducted beneath the less dense continental crust of the South American Plate.

The Nazca and South American plates are converging at a rate of approximately 80mm / year. This causes stress to accumulate resulting in elastic strain which stores elastic potential energy. Once the stress exceeds the strength of the rocks in the crust a brittle failure occurs, causing in this case thrust faulting to occur. The stored elastic strain energy is released in the form of seismic waves.

This form of thrust faulting usually results in the most powerful earthquakes and in the past Chile has experienced a magnitude 9.5 earthquake caused by the same tectonic plate motions - the most powerful ever recorded.

Please see the related question for further information.

Answer 2

usually earthquakes happen in poor countries like India and countries in Asia. But sometimes earthquakes happen big and rich places like California and you don't know when they will happen they might happen tomorrow and they might happen in hundred years time. But scientific people know that they will happen.

Answer 3

A earthquake happens when plates move under the ground.