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In its most general sense, the word earthquake is used to describe any seismic event that generates seismic waves. Earthquakes can occur naturally or be induced by human activities, such as mining, fracking, and nuclear tests. The initial point of rupture is called the hypocenter or focus, while the ground level directly above it is the epicenter.
Earthquakes are common on the West Coast, with multiple plate boundaries like the San Andreas fault making geologic activity more likely. They are rarer on the East Coast, but they do happen .
The earthquake cycle refers to the phenomenon that earthquakes repeatedly occur on the same fault as the result of continual stress accumulation and periodic stress release. [ 1 ] [ 2 ] Earthquake cycles can occur on a variety of faults including subduction zones and continental faults.
This results in the hanging wall flat (or a portion thereof) lying atop the foot wall ramp as shown in the fault-bend fold diagram. Thrust faults form nappes and klippen in the large thrust belts. Subduction zones are a special class of thrusts that form the largest faults on Earth and give rise to the largest earthquakes.
About 55 earthquakes a day – 20,000 a year – are recorded by the National Earthquake Information Center.Most are tiny and barely noticed by people living where they happen. But some are strong ...
The path that a wave takes between the focus and the observation point is often drawn as a ray diagram. Each path is denoted by a set of letters that describe the trajectory and phase through the Earth. In general, an upper case denotes a transmitted wave and a lower case denotes a reflected wave. The two exceptions to this seem to be "g" and "n".
This deformation may build at the rate of a few centimeters per year. When the accumulated strain is great enough to overcome the strength of the rocks, the result is a sudden break, or a springing back to the original shape as much as possible, a jolt which is felt on the surface as an earthquake. This sudden movement results in the shift of ...
New Jersey experienced a 4.8 magnitude earthquake, according to the U.S. Geological Survey. ... The edges of the plates, or plate boundaries, are made up of many faults, and most earthquakes occur ...