Earthquakes are the result of plate tectonics, or shifting plates in the crust of Earth, and quakes occur when the frictional stress of gliding plate boundaries builds and causes failure at a fault line. In an earthquake, elastic strain energy is released and waves radiate, shaking the ground. Scientists can predict where major temblors might occur in a general sense, but research does not yet allow forecasts for specific locations or accurate predictions of timing. Major earthquakes, some generating tsunamis, have leveled entire cities and affected whole countries. Relatively minor earthquakes can also be induced, or caused by human activity, including extraction of minerals from Earth and the collapse of large buildings.
A magnitude-7.1 earthquake that struck central Mexico yesterday (Sept. 20) left more than 200 people dead, with residents working through the night searching for survivors in piles of rubble from collapsed buildings, according to news reports.
The strongest earthquake to hit Mexico in 100 years struck off the country's southern coast late Thursday night local time, killing at least five people and sending residents fleeing into the streets.