Earthquake Geo Facts

Earthquake Geo Facts — page 3
What is an Earthquake An earthquake is the shaking of the ground caused by movements in the Earth’s crust During a large earthquake the ground shakes violently and buildings collapse Cracks appear in the ground and loud noises ring through the air as structures and objects fall For people who live in earthquake-prone areas quakes are a constant risk Shockwaves Movement in the Earth’s crust the outer layer of the Earth causes strain to build up between large plates or blocks of rock trying to move past each other Stored energy is released in giant shockwaves called seismic waves These intense vibrations cause damage to buildings and streets FOCUS ON San Francisco 1906 page 10 Regular events Scientists estimate that there are several million earthquakes every year However the huge majority of them go unnoticed as they are too small to be detected or happen in remote areas 4 FOCUS ON Peru 1970 page 16