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Coulomb Stress Transfer
Coulomb stress transfer is a seismic-related geological process of stress changes to surrounding material caused by local discrete deformation events. Using mapped displacements of the Earth's surface during earthquakes, the computed Coulomb stress changes suggest that the stress relieved during an earthquake not only dissipates but can also move up and down fault segments, concentrating and promoting subsequent tremors. Importantly, Coulomb stress changes have been applied to earthquake-forecasting models that have been used to assess potential hazards related to earthquake activity. Coulomb stress change The Coulomb failure criterion requires that the Coulomb stress exceeds a value σf defined by the shear stress τB, normal stress σB, pore pressure p, and coefficient of friction μ of a failure plane, such that It is also often assumed that changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the fault plane. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 planet-like bodies. It also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, glacial, fluvial, oceanic, atmospheric, and artificial processes such as explosions. A related field that uses geology to infer information regarding past earthquakes is paleoseismology. A recording of Earth motion as a function of time is called a seismogram. A seismologist is a scientist who does research in seismology. History Scholarly interest in earthquakes can be traced back to antiquity. Early speculations on the natural causes of earthquakes were included in the writings of Thales of Miletus (c. 585 BCE), Anaximenes of Miletus (c. 550 BCE), Aristotle (c. 340 BCE), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismicity
Seismicity is a measure encompassing earthquake occurrences, mechanisms, and magnitude at a given geographical location. As such, it summarizes a region's seismic activity. The term was coined by Beno Gutenberg and Charles Francis Richter in 1941. Seismicity is studied by geophysicists. Calculation of seismicity Seismicity is quantitatively computed. Generally, the region under study is divided in equally sized areas defined by latitude and longitude, and the Earth's interior is divided into various depth intervals on account of Earth's layering: 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; : _0: interval of longitude : _0: interval of the hypocenter; : _0: interval of the time of the seismic event. : The result is seismicity as energy per cubic unit. See also * Moment magnitude scale * Plate tectonics * Seismology Seismology (; f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1981 Dawu Earthquake
The 1981 Dawu earthquake occurred on , in Sichuan, China. Registering a surface wave magnitude of 6.8, the earthquake killed about 150 people and injured roughly 300 more. It caused comprehensive damage within close range of its epicenter. Background China has an extensive history of catastrophic earthquakes that ranges back to 1290. The first verified earthquake took place in Chih-li Zhili, alternately romanized as Chihli, was a northern administrative region of China since the 14th-century that lasted through the Ming dynasty and Qing dynasty until 1911, when the region was dissolved, converted to a province, and renamed ..., killing roughly 100,000 people. The next great earthquake was probably the 1556 Shaanxi earthquake, the most devastating earthquake of all time. Roughly 830,000 were killed by the event. Other earthquakes in 1917, 1918, 1920, 1923, 1925, 1927, 1931, 1932, 1933, 1948, 1950, 1966, 1969, 1970, 1974, 1975, 1976 each killed at least one thousand peopl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1783 Calabrian Earthquakes
The 1783 Calabrian earthquakes were a sequence of five strong earthquakes that hit the region of Calabria in southern Italy (then part of the Kingdom of Naples), the first two of which produced significant tsunamis. The epicenters form a clear alignment extending nearly 100 km from the Straits of Messina to about 18 km SSW of Catanzaro. The epicenter of the first earthquake occurred in the plain of Palmi. The earthquakes occurred over a period of nearly two months, all with estimated magnitudes of 5.9 or greater. Estimates of the total number of deaths lie in the range 32,000 to 50,000. Tectonic setting The southwestern part of Calabria and the eastern part of Sicily are areas of active crustal extension within the ''Siculo–Calabrian Rift Zone''. This 350 km long zone developed within the Apennine chain during the Pleistocene and takes up WNW–ESE directed extension. Events February 5 This earthquake, with an estimated magnitude of 7.0, affected a large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1703 Apennine Earthquakes
The 1703 Apennine earthquakes were a sequence of three earthquakes of Richter magnitude scale, magnitude ≥6 that occurred in the central Apennines of Italy, over a period of 19 days. The epicenters were near Norcia (14 January), Montereale (AQ), Montereale (16 January) and L'Aquila (2 February), showing a southwards progression over about . These events involved all of the known active Fault (geology), faults between Norcia and L'Aquila. A total of about 10,000 people are estimated to have died as a result of these earthquakes, although because of the overlap in areas affected by the three events, casualty numbers remain highly uncertain. Tectonic setting The central part of the Apennines has been characterised by extensional tectonics since the Pliocene Epoch (geology), epoch (i.e. about the last 5 million years), with most of the active faults being normal in type and NW-SE trending. The extension is due to the back-arc basin in the Tyrrhenian Sea opening faster than the Afric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Anatolian Fault
The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral strike-slip fault in northern Anatolia, and is the transform boundary between the Eurasian Plate and the Anatolian Plate. The fault extends westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea for a length of 1500 kilometers. It runs about 20 km south of Istanbul. The North Anatolian Fault is similar in many ways to the San Andreas Fault in California. Both are continental transforms with similar lengths and slip rates. The Sea of Marmara near Istanbul is an extensional basin similar to the Salton Trough in California, where a releasing bend in the strike-slip system creates a pull-apart basin. Significant earthquakes Since the disastrous 1939 Erzincan earthquake, there have been seven earthquakes measuring over 7.0 in magnitude, each happening at a point progressively further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Anatolian Fault
The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral strike-slip fault in northern Anatolia, and is the transform boundary between the Eurasian Plate and the Anatolian Plate. The fault extends westward from a junction with the East Anatolian Fault at the Karliova Triple Junction in eastern Turkey, across northern Turkey and into the Aegean Sea for a length of 1500 kilometers. It runs about 20 km south of Istanbul. The North Anatolian Fault is similar in many ways to the San Andreas Fault in California. Both are continental transforms with similar lengths and slip rates. The Sea of Marmara near Istanbul is an extensional basin similar to the Salton Trough in California, where a releasing bend in the strike-slip system creates a pull-apart basin. Significant earthquakes Since the disastrous 1939 Erzincan earthquake, there have been seven earthquakes measuring over 7.0 in magnitude, each happening at a point progressively further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aftershock
In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms. Distribution of aftershocks Most aftershocks are located over the full area of fault rupture and either occur along the fault plane itself or along other faults within the volume affected by the strain associated with the main shock. Typically, aftershocks are found up to a distance equal to the rupture length away from the fault plane. The patte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1992 Big Bear Earthquake
The 1992 Big Bear earthquake occurred at on June 28 in Big Bear Lake, California, with a Moment magnitude scale, moment magnitude of 6.5 and a maximum perceived intensity of VIII (''Severe'') on the Mercalli intensity scale. The earthquake occurred at a relatively shallow depth of . Earthquake The Big Bear earthquake happened east of Los Angeles, and 3 hours 26 minutes after the M 7.3 1992 Landers earthquake occurred 22 miles (35 km) to the east. It was first believed to be an aftershock of the larger event. However, the United States Geological Survey determined that it was a separate, but related, shock. The two events are considered a regional sequence, rather than a main shock and aftershock. They were part of a complex pattern of regional stress adjustment that also led to the 1999 Hector Mine earthquake. Damage In the Big Bear area, severe damage was reported. Roughly 2,600 chimneys were destroyed, 20 homes were knocked off their foundations, and many unreinforced m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landers, California
Landers is an unincorporated community in the High Desert region of the Mojave Desert, in San Bernardino County, Southern California. Landers' population, as of 2017, is 2,982 people. Its residents are sometimes referred to as "Landroids"—an allusion to the popular UFO culture in the area—and its official slogan is "Beautiful Skies, Miles of Smiles," adopted pursuant to a contest held by the Landers Association in early 2014. It was submitted by Ms. McCall's 3rd and 4th grade class at Landers Elementary School and was unveiled on June 10, 2014. However, for almost half a century, Landers has been known to its residents as "the land of 1000 vistas". History The Landers area was originally settled in the early 20th century by prospectors who came to mine gold in Goat Mountain, starting with Charles Reche in 1914. From the late 1940s through the 1970s, Landers was a popular gathering point for conventions of UFO enthusiasts, with the primary destinations of interest being th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1992 Landers Earthquake
The 1992 Landers earthquake occurred on Sunday, June 28 with an epicenter near the town of Landers, California, in San Bernardino County. The shock had a moment magnitude of 7.3 and a maximum Mercalli intensity of IX (''Violent''). Earthquake At 4:57 a.m. local time (11:57 UTC) on June 28, 1992, a magnitude 7.3 earthquake awoke much of Southern California. Though it turned out it was not the so-called " Big One" as many people would think, it was still a very strong earthquake. The shaking lasted for two to three minutes. Although this earthquake was much more powerful than the 1994 Northridge earthquake, the damage and loss of life were minimized by its location in the sparsely-populated Mojave Desert. The earthquake was a right-lateral strike-slip event, and involved the rupture of several different faults over a length of . The names of those that were involved are the Johnson Valley, Kickapoo (also known as Landers), Homestead Valley, Homestead/Emerson, Emerson Va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exogenous
In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system. Economics In an economic model, an exogenous change is one that comes from outside the model and is unexplained by the model. Such changes of an economic model from outside factors can include the influence of technology, in which this had previously been noted as an exogenous factor, but has rather been noted as a factor that can depict economic forces as a whole. In economic sociology, Project IDEA (Interdisciplinary Dimensions of Economic Analysis) gave notion to understanding the exogenous factors that play a role within economic theory. Developed from the International Social Science Council (ISSC) in the year of 1982, Project IDEA was founded to gather ideas from economists and sociologists in order to conceptualize what economic sociology incorporates, as they have sought ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
