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Earthquakes In Portugal
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 intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quake Epicenters 1963-98
Quake may refer to: Seismology * Earthquake, a shaking of the earth's surface * Quake (natural phenomenon), surface shaking on any astronomical body Arts and entertainment * ''Quake'' (album), a 2003 album by Erik Friedlander * ''Quake'' (film), a 1992 American direct-to-video film * ''The Quake'' (film), a 2018 Norwegian film * ''Quake'' (series), a series of first-person shooter games ** ''Quake'' (video game), the 1996 first game in the series *** ''Quake'' engine, a game engine by ID Software, first used in the 1996 game *** ''Quake'' (original soundtrack), by Trent Reznor and Nine Inch Nails, 1996 ** ''Quake II'' engine, the 1997 second iteration of the game engine, first used in ''Quake II'' * WQKE, The Quake, an FM radio station in Plattsburgh, New York, US * Quake, a Transformers comics character * Quake, a superhero code name used by the Marvel Comics character Daisy Johnson Other uses * Quake (cereal), a breakfast cereal marketed with Quisp * Quake Inc., now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stick-slip Phenomenon
The stick–slip phenomenon, also known as the slip–stick phenomenon or simply stick–slip, is the spontaneous jerking motion that can occur while two objects are sliding over each other. Cause Below is a simple, heuristic description of stick–slip phenomena using classical mechanics that is relevant for engineering descriptions. However, in actuality, there is little consensus in academia regarding the actual physical description of stick–slip which follows the lack of understanding about friction phenomena in general. The generally agreed upon view is that stick–slip behavior results from common phonon modes (at the interface between the substrate and the slider) that are pinned in an undulating potential well landscape that un-pin (slip) and pin (stick) primarily influenced by thermal fluctuations. However, stick–slip frictional behaviour is encountered over a wide range of length scales from the atomic up to the tectonic, and there is no single underlying physical m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Andreas Fault
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). The fault divides into three segments, each with different characteristics and a different degree of earthquake risk. The slip rate along the fault ranges from /yr. It was formed by a transform boundary. The fault was identified in 1895 by Professor Andrew Lawson of UC Berkeley, who discovered the northern zone. It is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, Lawson actually named it after the surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California. In 1953, geologist Thomas Dibblee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2004 Indian Ocean Earthquake And Tsunami
An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time ( UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Sumatra, Indonesia. It was an undersea megathrust earthquake that registered a magnitude of 9.1–9.3 , reaching a Mercalli intensity up to IX in certain areas. The earthquake was caused by a rupture along the fault between the Burma Plate and the Indian Plate. A series of massive tsunami waves grew up to high once heading inland, after being created by the underwater seismic activity offshore. Communities along the surrounding coasts of the Indian Ocean were devastated, and the tsunamis killed an estimated 227,898 people in 14 countries, making it one of the deadliest natural disasters in recorded history. The direct results caused major disruptions to living conditions and commerce in coastal provinces of surrounded countries, incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1960 Valdivia Earthquake
The 1960 Valdivia earthquake and tsunami ( es, link=no, Terremoto de Valdivia) or the Great Chilean earthquake (''Gran terremoto de Chile'') on 22 May 1960 was the most powerful earthquake ever recorded. Various studies have placed it at 9.4–9.6 on the moment magnitude scale. It occurred in the afternoon (19:11 GMT, 15:11 local time), and lasted for approximately 10 minutes. The resulting tsunamis affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands. The epicenter of this megathrust earthquake was near Lumaco, approximately south of Santiago, with Valdivia being the most affected city. The tremor caused localised tsunamis that severely battered the Chilean coast, with waves up to . The main tsunami traveled across the Pacific Ocean and devastated Hilo, Hawaii, where waves as high as were recorded over from the epicenter. The death toll and monetary losses arising from this widespread disaster are not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1957 Andreanof Islands Earthquake
The 1957 Andreanof Islands earthquake took place on March 9 with a moment magnitude of 8.6 and a maximum Mercalli intensity of VIII (''Severe''). It occurred south of the Andreanof Islands group, which is part of the Aleutian Islands arc. The event occurred along the Aleutian Trench, the convergent plate boundary that separates the Pacific Plate and the North American Plates near Alaska. A basin wide tsunami followed, with effects felt in Alaska and Hawaii. Total losses were around $5 million. Tectonic setting The Aleutian Subduction Zone is the convergent boundary of the Pacific and North American Plates. This oceanic trench runs from the Kuril Subduction Zone in the west to the Yakutat Collision Zone in the east. At each end of the subduction zone are right-lateral transform faults, including the Queen Charlotte Fault in the east, and a similar structure at the far west end of the arc near Attu Island. Earthquake Because the shock occurred before the World Wide Standardis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strike And Dip
Strike and dip is a measurement convention used to describe the orientation, or attitude, of a planar geologic feature. A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination measured downward from horizontal. They are used together to measure and document a structure's characteristics for study or for use on a geologic map. A feature's orientation can also be represented by dip and dip direction, using the azimuth of the dip rather than the strike value. Linear features are similarly measured with trend and plunge, where "trend" is analogous to dip direction and "plunge" is the dip angle. Strike and dip are measured using a compass and a clinometer. A compass is used to measure the feature's strike by holding the compass horizontally against the feature. A clinometer measures the features dip by recording the inclination perpendicular to the strike. These can be done separately, or together using a tool such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplate Earthquake
An interplate earthquake is an earthquake that occurs at the boundary between two tectonic plates. Earthquakes of this type account for more than 90 percent of the total seismic energy released around the world. If one plate is trying to move past the other, they will be locked until sufficient stress builds up to cause the plates to slip relative to each other. The slipping process creates an earthquake with relative displacement on either side of the fault, resulting in seismic waves which travel through the Earth and along the Earth's surface. Relative plate motion can be lateral as along a transform fault boundary, vertical if along a convergent boundary (i.e. subduction or thrust/reverse faulting) or a divergent boundary (i.e. rift zone or normal faulting), and oblique, with horizontal and lateral components at the boundary. Interplate earthquakes associated at a subduction boundary are called megathrust earthquakes, which include most of the Earth's largest earthquakes. Intr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structure Of The Earth
The internal structure of Earth is the solid portion of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core. Scientific understanding of the internal structure of Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through Earth, measurements of the gravitational and magnetic fields of Earth, and experiments with crystalline solids at pressures and temperatures characteristic of Earth's deep interior. Global properties The force exerted by Earth's gravity can be used to calculate its mass. Astronomers can also calculate Earth's mass by observing the motion of orbiting satellites. Earth's average dens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastic Potential Energy
Elastic energy is the mechanical potential energy stored in the configuration of a material or physical system as it is subjected to elastic deformation by work performed upon it. Elastic energy occurs when objects are impermanently compressed, stretched or generally deformed in any manner. Elasticity theory primarily develops formalisms for the mechanics of solid bodies and materials. (Note however, the work done by a stretched rubber band is not an example of elastic energy. It is an example of entropic elasticity.) The elastic potential energy equation is used in calculations of positions of mechanical equilibrium. The energy is potential as it will be converted into other forms of energy, such as kinetic energy and sound energy, when the object is allowed to return to its original shape (reformation) by its elasticity. U = \frac 1 2 k\, \Delta x^2 The essence of elasticity is reversibility. Forces applied to an elastic material transfer energy into the material whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture (geology)
A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock. Fractures are commonly caused by stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water or hydrocarbons. Highly fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity. Brittle deformation Fractures are forms of brittle deformation. There are two types of primary brittle deformation processes. Tensile fracturing results in ''joints''. ''Shear fractures'' are the first initial breaks resulting from shear forces exceeding the cohesive strength in that plane. After those two initial deformations, several other types of secondary brittle deformation can be observed, such as ''frictional s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elastic-rebound Theory
__NOTOC__ In geology, the elastic-rebound theory is an explanation for how energy is released during an earthquake. As the Earth's crust deforms, the rocks which span the opposing sides of a fault are subjected to shear stress. Slowly they deform, until their internal rigidity is exceeded. Then they separate with a rupture along the fault; the sudden movement releases accumulated energy, and the rocks snap back almost to their original shape. The previously solid mass is divided between the two slowly moving plates, the energy released through the surroundings in a seismic wave. Theory After the great 1906 San Francisco earthquake, geophysicist Harry Fielding Reid examined the displacement of the ground surface along the San Andreas Fault in the 50 years before the earthquake.Reid, H.F., ''The Mechanics of the Earthquake, The California Earthquake of April 18, 1906; Report of the State Investigation Commission,'' Vol.2, Carnegie Institution of Washington, Washington, D.C. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
