According to the United States Geological Survey, several million earthquakes occur worldwide each year. It is difficult to refine this estimation to an exact number because many earthquakes go undetected, either because they occur in locations that are uninhabited or barely inhabited, or they are too small in magnitude to be detected by seismographs or other forms of detection.Know More
While the number of smaller earthquakes has seemed to increase over the past decade, the number of earthquakes measuring at a 6.0 magnitude or higher have remained somewhat stagnant. This may be due to the fact that more seismographs have been introduced to areas of the world, allowing scientists to detect and record smaller earthquakes that otherwise would not have been detected. Most earthquakes that have occurred worldwide in the last decade have been calculated between and 2.0 and 5.0 magnitude. Approximately 17 earthquakes measuring above an 8.0 magnitude have occurred since the year 2000. None of these large earthquakes occurred in the U.S.
The average number of magnitude 5.0 to 7.9 earthquakes occurring worldwide each year since 1990 is close to 1,500. It is important to note that the U.S. Geological Survey National Earthquake Information Center does not actively locate and record earthquakes with a magnitude of 4.5 or lower occurring outside of the U.S., unless the earthquake causes considerable damage.Learn more about Earthquakes
Earthquakes are usually triggered when rock located beneath the ground, on top of fault lines, breaks and suddenly releases a significant amount of energy. The immediate and rapid release of energy caused by earthquakes generates seismic waves, which cause shaking motions that start below the Earth’s surface and spread across large distances.Full Answer >
Earthquakes happen daily across the United States, though they vary in magnitude. For instance, the United States had 3,836 earthquakes in 2012, but only five of them were above six on the Richter scale, and none of them exceeded seven.Full Answer >
Most earthquakes occur along the boundaries between the Earth's tectonic plates. The crust of the Earth is divided into plates. When a plate collides with or slides past another plate, this causes earthquakes. For example, as the Pacific plate moves past the North American plate, many earthquakes occur along the coast of California.Full Answer >
Earthquakes occur most often along the edges of oceanic and continental plates. Oceanic plates are the large pieces of the Earth's crust that are located beneath the oceans. Continental plates hold the Earth's large land masses.Full Answer >