Role of plate tectonics
Plate tectonics is the concept of the earth’s crust moving on the mantle. The plates either collide, slide under or move past an adjacent plate.
The 1960 Chile earthquake was caused by the collision between the Nazca and the South American plates. The Nazca plate has been colliding and subducting underneath the South American plate for thousands of years. At a subduction zone, the piece of crust that is descending gets caught in the trench and tension builds up as it tries to descend further. The quake occurred when, the Nazca plate moved 15 metres under the South American plate, which became stuck and elastic energy was built among the rocks, causing the South American plate to crush on the edges. This measure triggered land to lift upwards to create hills, while other lands dropped to make valleys. Ultimately the rocks broke, releasing all the energy in the rocks, travelling around the earth as seismic waves. Usually the Nazca plate only travels 9 centimetres a year, but due to the intense movement of the plates, the earthquake lead to a 9.5 magnitude quake. A tsunami was provoked by the force of the quake, as the Nazca plate moved on the Pacific Ocean, travelling thousands of kilometres.