Epicenter, epicenter or epicenter in seismology is a point on the Earth's surface just above the hypocenter or focus, the point at which an earthquake or an underground explosion originates.
Video Epicenter
Surface damage
In most earthquakes, the epicenter is the point where the greatest damage occurs, but the length of the subsurface fault damage is very long, and damage can spread to the surface throughout the breaking zone. For example, a magnitude 7.9 earthquake in Alaska, the epicenter is at the western end of the damage, but the greatest damage is about 330 km away on the eastern end.
Maps Epicenter
Epicentral Distance
During an earthquake, seismic waves propagate in all directions from the hypocenter. Seismic shadows occur on the opposite side of the Earth from earthquake epicenteres because the planet's outer liquid core refracts longitudinally or compressively (P-wave) when absorbing transverse or shear wave (S-wave) waves. Outside the seismic shadow zone, both types of waves can be detected but, because of their different velocities and paths through Earth, they arrive at different times. By measuring the time difference in the seismograph and the distance on the time travel graph in which the P-wave and S-wave have the same separation, the geologist can calculate the distance to the epicenter of the earthquake. This distance is called the epicentral distance , usually measured in Ã, Â ° (degrees) and denoted as? (delta) in seismology.
Once the distance from the epicenter has been calculated from at least three seismograph measuring stations, a point can be found, using trilateration.
Epicentral distances are also used in calculating the magnitude of seismic developed by Richter and Gutenberg.
Derivation and use
This word comes from the new Latin noun epicentrum , the Latin word from the ancient Greek adjective ?????????? ( epicentros ), "occupying the cardinal point, located in the middle", from ??? ( epi ) "on, up, on" and ??????? ( kentron ) "center". The term was coined by Irish earthquake expert Robert Mallet.
This is also used to mean center. For example, "Travel is limited in China's provinces that are considered central to the SARS outbreak." Modern American usage Garner gives some examples of such usage. Garner also refers to William Safire's article in which Safire quotes a geophysicist who associates the use of the term with "false knowledge on the part of the author combined with scientific illiteracy in the copy editor's section". Nevertheless, Garner has noted that this use may illustrate "an unstable and potentially destructive environmental focal point."
References
Source of the article : Wikipedia
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