Due to friction on fault surfaces, faults that make up the plate boundaries generally do not slip continuously. The Earth’s plates are moving at speeds of centimeters per year, which produces deformation at plate boundaries. Most earthquakes are the result of plate tectonic processes. The release of elastic energy associated with earthquakes generates seismic waves that propagate through the Earth and along the Earth’s surface across large distances. Individuals, governments, and organizations can respond to the hazard by understanding the probability and the likely effects of significant events preparing emergency response plans enhancing public knowledge about what to do in case of an earthquake and taking specific steps (such as reinforcing critical or weak structures) to reduce the risk of earthquakes.Įarthquakes are often defined as ground vibrations related to a release of elastic energy, or as the sudden slip of a section of a fault plane, releasing stored elastic energy the latter is the most common source of significant ground vibrations. When significant earthquakes occur anywhere in the world, such as the December 2004 tsunami-generating event in Indonesia that killed more than 200,000 people, or the October 2005 earthquake in Pakistan that killed more than 70,000 people, emergency response and relief efforts come from around the globe, and there is renewed interest in understanding the causes and in mitigating the devastating effects of earthquakes.Įarthquakes can be significant hazards, as evidenced by occasional damaging and deadly events. The vast majority of earthquakes are caused by sudden slip along faults, resulting in seismic waves that shake the ground, often with sufficient force to damage structures or trigger other events, such as landslides. Most earthquakes are associated with natural, dynamic processes that shape Earth’s landscape.
Thus, the earthquake process can be interesting and even frightening to people. Although earthquakes happen frequently in many parts of the world, any occurrence of a moderate to large event is sudden and unexpected.