Earthquakes occur when two blocks of earth suddenly slip past each other. This sudden release of energy causes the seismic waves that make the ground shake. The surface where they slip is known as the fault or fault plane.Know More
According to Universe Today, earthquakes occur as a result of tectonic plates colliding and volcanic eruption. To be considered an earthquake, a shock wave has to be of natural origin. Earthquakes occur when rock underground suddenly breaks along a fault. The spot underground where the rocks break is the focus of the earthquake. The place directly above the focus on top of the ground is the epicenter of the earthquake.
Major earthquakes are often preceded by more frequent minor shocks, known as foreshocks, as the rocks begin to move. Following the main shock, further movements, known as aftershocks, occur as the rock masses settle in their new positions. Aftershocks cause problems for rescue services because they can bring down buildings that were weakened by the primary earthquake.
Earthquake-like seismic waves can also be caused by explosions underground. These explosions are triggered in order to break rock while making tunnels for roads, railroads, subways or mines. These manmade explosions, however, don't cause very strong seismic waves.Learn more in Earthquakes
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 >
The United States Geological Survey estimates that there are around 50 earthquakes per day in the world that can be located. This amounts to around 20,000 earthquakes annually.Full Answer >
While earthquakes can occur almost anywhere, they are most common around the edges of the great tectonic plates of the Earth's crust. The plates are always in motion, and the edges tend to rub up against one another, building up the energy that results in an earthquake.Full Answer >
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.Full Answer >