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1959 Coatzacoalcos Earthquake
The 1959 Coatzacoalcos earthquake (also known as the Jáltipan earthquake) occurred at 02:25 local time on August 26 near the Mexican state of Veracruz. The earthquake measured 6.4 at a depth of , and had a maximum Modified Mercalli intensity of VIII (''Severe''). It had an epicenter immediately off the coast of Coatzacoalcos (in the Gulf of Mexico). The shallow back-arc thrust faulting earthquake damaged the cities of Acayucan, Coatzacoalcos, Jáltipan and Minatitlán. A total of 25 people died, including 10 from Jáltipan while a further 200 were injured. The Middle America Trench, a subduction zone that borders the southwestern coast of Mexico and Central America, accounts for much of the seismicity in Mexico. The eastern side of the country near the Gulf of Mexico rarely experiences large earthquakes although they have been recorded around the Veracruz area, where seismicity is higher compared to other parts of the gulf. Seismicity in the gulf is attributed to back-arc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Time Zone
The North American Central Time Zone (CT) is a time zone in parts of Canada, the United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ..., Mexico, Central America, and a few Caribbean Islands, Caribbean islands. In parts of that zone (20 states in the US, three provinces or territories in Canada, and several border municipalities in Mexico), the Central Time Zone is affected by two time designations yearly: Central Standard Time (CST) is observed from the first Sunday in November to the second Sunday in March. It is UTC−06:00, six hours behind Coordinated Universal Time (UTC) and designated internationally as UTC−6. From the second Sunday in March to the first Sunday in November the same areas observe daylight saving time (DST), creating the designation of Central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tehuantepec Ridge
The Tehuantepec Ridge (Tehuantepec Fracture Zone, Tehuntepec Ridge) is a linear undersea ridge located off the west coast of Mexico in the Pacific Ocean. It is the remnant of an old fracture zone, and not a tectonic spreading center ridge (''see'' mid-ocean ridge). It extends from the eastern end of the Clipperton fracture zone northeastward toward Mexico into Chiapas and El Chichón until it is subducted into the Middle America Trench. It lies within the tectonic Cocos plate, separating the lower and older seafloor of the Guatemala Basin which lies southeast of the ridge from higher and younger seafloor which lies to its north-west. Current research indicates that the ridge was formed as a fracture zone and transform fault along the East Pacific Rise. As a result of a change in the motion of the Pacific plate about 13 million years ago, there was also a change in the orientation of the East Pacific Rise, which in turn reoriented the fracture zone, creating the current align ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust Fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an ''overthrust'' or ''overthrust fault''. Erosion can remove part of the overlying block, creating a ''fenster'' (or ''window'') – when the underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called ''klippen'' (singular '' klippe''). Blind thrust faults If the fault plane terminates before it reaches the Earth's surface, it is called a ''blind thrust'' fault. Because of the lack of surface evidence, blind thrust fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Region
The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back-arc region is part of the continental platform, either dry land ( subaerial) or forming shallow marine basins. Formation Back-arc deformation is a product of subduction at convergent plate tectonic boundaries. It initiates and evolves behind the volcanic arc on the overriding plate of a subduction zone. The stresses responsible for the deformation in this region of a subduction zone result from a combination of processes. The absolute motion of the upper plate as it moves towards or away from the trench strongly contributes to deformation in the back-arc region. Since the downgoing slab is partly anchored in the viscous layers of the mantle, and therefore its lateral movement is significantly slower than the surface plate, then any motion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isthmus
An isthmus (; : isthmuses or isthmi) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus, a narrow stretch of sea between two landmasses that connects two larger bodies of water. Isthmus vs land bridge vs peninsula ''Isthmus'' and ''land bridge'' are related terms, with isthmus having a broader meaning. A land bridge is an isthmus connecting Earth's major land masses. The term ''land bridge'' is usually used in biogeology to describe land connections that used to exist between continents at various times and were important for the migration of people and various species of animals and plants, e.g. Beringia and Doggerland. An isthmus is a land connection between two bigger landmasses, while a peninsula is rather a land protrusion that is connected to a bigger landmass on one side only and surrounded by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isthmus Of Tehuantepec
The Isthmus of Tehuantepec () is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Before the opening of the Panama Canal, it was a major overland transport route known simply as the Tehuantepec Route. The name is taken from the town of Santo Domingo Tehuantepec in the state of Oaxaca; this was derived from the Nahuatl term (" jaguar mountain"). Geography The isthmus includes the part of Mexico lying between the 94th and 96th meridians west longitude, or the southeastern parts of Veracruz and Oaxaca, including small areas of Chiapas and Tabasco. The states of Tabasco and Chiapas are east of the isthmus, with Veracruz and Oaxaca on the west. At its narrowest point, the isthmus is across from gulf to gulf, or to the head of Laguna Superior on the Pacific coast. The Sierra Madre del Sur mountain range breaks down at this point into a broad, plateau-like ridge, whose elevation, at the highest point reached by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Margin
A passive margin is the transition between Lithosphere#Oceanic lithosphere, oceanic and Lithosphere#Continental lithosphere, continental lithosphere that is not an active plate continental margin, margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting forms new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extensional tectonics, extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally formed by rifting is known as a passive margin. Global distribution Passive margins are found at every ocean and continent boundary that is not marked by a Fault (geology)#Strike-slip faults, strike-slip fault or a subduction, subduction zone. Passive margins define the region around the Arctic Ocean, Atlantic Ocean, and western Indian Ocean, and define the entire coasts of Africa, Australia, Greenla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth's Mantle
Earth's mantle is a layer of silicate mineral, silicate rock between the Earth's crust, crust and the Earth's outer core, outer core. It has a mass of and makes up 67% of the mass of Earth. It has a thickness of making up about 46% of Earth's radius and 84% of Earth's volume. It is predominantly solid but, on geologic time scales, it behaves as a viscosity, viscous fluid, sometimes described as having the consistency of caramel. Partial melting of the mantle at mid-ocean ridges produces oceanic crust, and partial melting of the mantle at subduction zones produces continental crust. Structure Rheology Earth's upper mantle is divided into two major rheology, rheological layers: the rigid lithosphere comprising the uppermost mantle (the lithospheric mantle), and the more ductile asthenosphere, separated by the Lithosphere-Asthenosphere boundary, lithosphere-asthenosphere boundary. Lithosphere underlying ocean crust has a thickness of around , whereas lithosphere underlying cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plane (geometry)
In mathematics, a Euclidean plane is a Euclidean space of dimension two, denoted \textbf^2 or \mathbb^2. It is a geometric space in which two real numbers are required to determine the position of each point. It is an affine space, which includes in particular the concept of parallel lines. It has also metrical properties induced by a distance, which allows to define circles, and angle measurement. A Euclidean plane with a chosen Cartesian coordinate system is called a '' Cartesian plane''. The set \mathbb^2 of the ordered pairs of real numbers (the real coordinate plane), equipped with the dot product, is often called ''the'' Euclidean plane or ''standard Euclidean plane'', since every Euclidean plane is isomorphic to it. History Books I through IV and VI of Euclid's Elements dealt with two-dimensional geometry, developing such notions as similarity of shapes, the Pythagorean theorem (Proposition 47), equality of angles and areas, parallelism, the sum of the angles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Mechanism
The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event, it refers to the orientation of the fault plane that slipped, and the slip Euclidean vector, vector and is also known as a fault-plane solution. Focal mechanisms are derived from a solution of the moment tensor for the earthquake, which itself is estimated by an analysis of observed seismic waveforms. The focal mechanism can be derived from observing the pattern of "first motions", whether the first arriving P waves break up or down. This method was used before waveforms were recorded and analysed digitally, and this method is still used for earthquakes too small for easy moment tensor solution. Focal mechanisms are now mainly derived using semi-automatic analysis of the recorded waveforms. Moment tensor solutions The moment tensor solution is displayed gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
