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Seismicity is a measure encompassing
earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that ...
occurrences, mechanisms, and
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
at a given
geographical Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and planets. The first person to use the word γεωγραφ ...
location. As such, it summarizes a region's seismic activity. The term was coined by
Beno Gutenberg Beno Gutenberg (; June 4, 1889 – January 25, 1960) was a German-American seismologist who made several important contributions to the science. He was a colleague and mentor of Charles Francis Richter at the California Institute of Technology ...

Beno Gutenberg
and
Charles Francis Richter Charles Francis Richter (); April 26, 1900 – September 30, 1985) was an American seismologist and physicist. Richter is most famous as the creator of the Richter magnitude scale, which, until the development of the moment magnitude scale in 19 ...
in 1941. Seismicity is studied by
geophysicists Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' somet ...
.


Calculation of seismicity

Seismicity is quantitatively computed. Generally, the region under study is divided in equally sized areas defined by
latitude In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines ...
and
longitude Longitude (, ), is a geographic coordinate that specifies the east–west position of a point on the Earth's surface, or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter ...
, and the
Earth's interior The internal structure of Earth, structure of the solid Earth, or simply structure of Earth refers to concentric spherical layers subdividing the Solid earth, i.e., excluding Earth's atmosphere and hydrosphere. It consists of an outer silicate so ...
is divided into various depth intervals on account of Earth's
layering Layering has evolved as a common means of vegetative propagation of numerous species in natural environments. Layering is also utilized by horticulturists to propagate desirable plants. Natural layering typically occurs when a branch touches th ...
: Up to depth, , and > . The usual formula to calculate seismicity is: S = \frac where : _i: is the energy of a single seismic event (i.e., earthquake); : _0: interval of
latitude In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines ...
; : _0: interval of
longitude Longitude (, ), is a geographic coordinate that specifies the east–west position of a point on the Earth's surface, or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter ...
: _0: interval of the
hypocenter A hypocenter (or hypocentre) (from grc, ὑπόκεντρον 'hypόkentron''for 'below the center') is the point of origin of an earthquake or a subsurface nuclear explosion. In seismology, it is a synonym of the focus. Outside seismology, the ...
; : _0: interval of the time of the seismic event. : The result is seismicity as energy per cubic unit.


See also

*
Moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...
*
Plate tectonics upright=1.35, Diagram of the internal layering of Earth showing the lithosphere above the asthenosphere (not to scale) Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is a ...
*
Seismology Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other pl ...
*
Wadati–Benioff zone 240px, Seismicity cross-section, 15 November 2006, 8.3 Mw event marked as star">2006 Kuril Islands earthquake">15 November 2006, 8.3 Mw event marked as star A Wadati–Benioff zone (also Benioff–Wadati zone or Benioff zone or Benioff seismic zone) ...


References

Seismology measurement
1940s neologisms{{NeologismsByDecade ...
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