Earthquake facts and a number of details about how Earthquakes work and form.
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are measured using observations from seismometers. Most earthquakes are measured mostly on the local magnitude scale, also referred to as the Richter scale. Magnitude 3 or lower earthquakes are mostly almost imperceptible and magnitude 7 and over potentially cause serious damage over large areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (11-03-2011), and it was the largest Japanese earthquake since records began.