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Seaquake
A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis. The magnitude can be measured scientifically by the use of the moment magnitude scale and the intensity can be assigned using the Mercalli intensity scale. Understanding plate tectonics helps to explain the cause of submarine earthquakes. The Earth's surface or lithosphere comprises tectonic plates which average approximately in thickness, and are continuously moving very slowly upon a bed of magma in the asthenosphere and inner mantle. The plates converge upon one another, and one subducts below the other, or, where there is only shear stress, move horizontally past each other (see transform plate boundary below). Little movements called fault creep are minor and not measurable. The plates meet with each other, and if rough spots cause the movement to stop at the edges, the motion of the plates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicenter
The epicenter (), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Determination The primary purpose of a seismometer is to locate the initiating points of earthquake epicenters. The secondary purpose, of determining the 'size' or magnitude must be calculated after the precise location is known. The earliest seismographs were designed to give a sense of the direction of the first motions from an earthquake. The Chinese frog seismograph would have dropped its ball in the general compass direction of the earthquake, assuming a strong positive pulse. We now know that first motions can be in almost any direction depending on the type of initiating rupture ( focal mechanism). The first refinement that allowed a more precise determination of the location was the use of a time scale. Instead of merely noting, or recording, the absolute motions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puerto Rico Trench
The Puerto Rico Trench is located on the boundary between the North Atlantic Ocean and Caribbean Sea, parallel to and north of Puerto Rico, where the oceanic trench reaches the deepest points in the Atlantic Ocean. The trench is associated with a complex transition from the Lesser Antilles frontal subduction zone between the South American plate and Caribbean plate to the oblique subduction zone and the strike-slip transform fault zone between the North American plate and Caribbean plate, which extends from the Puerto Rico Trench at the Puerto Rico–Virgin Islands microplate through the Cayman Trough at the Gonâve microplate to the Middle America Trench at the Cocos plate. Constituting the deepest points in the Atlantic Ocean, the trench is long and has a maximum documented depth between and . The deepest point is commonly referred to as the Milwaukee Deep, with the Brownson Deep naming the seabed surrounding it. However, more recently, the latter term has also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mariana Trench
The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deep sea, deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known depth is at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep. The deepest point of the trench is more than farther from sea level than the peak of Mount Everest. At the bottom of the trench, the water column above exerts a pressure of , more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%. The temperature at the bottom is . In 2009, the Mariana Trench was established as a National monument (United States), US National Monument, Mariana Trench Marine National Monument. One-celled organisms called monothalamea have been found in the trench at a record depth of below the sea surface by researchers from the Scrip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Trench
Oceanic trenches are prominent, long, narrow topography, topographic depression (geology), depressions of the seabed, ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of convergent boundary, convergent plate boundaries, along which lithosphere, lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about per year. A trench marks the position at which the flexed, subduction, subducting slab (geology), slab begins to d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by the radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle. These convection cells bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Sumatran Fault
The Great Sumatran fault, also known as Semangko fault, is a large strike-slip fault running the entire length of the island of Sumatra. This Indonesian island is located in a highly seismic area of the world, including a subduction zone off the west coast of the island. The Great Sumatran fault zone accommodates most of the strike-slip motion associated with the oblique convergence between the Indo-Australian plate and Eurasian plate The fault ends in the north near the city of Banda Aceh, which was devastated in the 2004 Indian Ocean earthquake. Geologic significance The Great Sumatran fault is part of the system where strain partitioning was first described in plate tectonics. The convergence between the Indo-Australian plate and the Sunda plate is not perpendicular to the plate boundary in this region. Instead, the two plates move at an oblique angle. Most of the convergent strain is accommodated by thrust motion at the plate boundary "megathrust" fault that defines th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology), crust result from the action of Plate tectonics, plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction, subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the Plane (geometry), plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geological maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonic Plate Boundaries
Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called ''tectonics''. Tectonic plates also occur in other planets and moons. Earth's lithosphere, the rigid outer shell of the planet including the crust and upper mantle, is fractured into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary (or fault): , , or . The relative movement of the plates typically ranges from zero to 10 cm annually. Faults tend to be geologically active, ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plates Tect2 En
Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: rice plate) * Plate, to present food, on a plate * Plate, forequarter cut of beef Places * Plate, Germany, municipality in Parchim, Mecklenburg-Vorpommern, Germany * Plate, borough of Lüchow, Lower Saxony, Germany * River Plate (other) * Tourelle de la Plate, lighthouse in France Science and technology Biology and medicine * Plate (anatomy), several meanings * Dental plate, also known as dentures * Dynamic compression plate, metallic plate used in orthopedics to fix bone * Microtiter plate (or microplate or microwell plate), flat plate with multiple "wells" used as small test tubes * Orthopedic plate, internal fixation used in orthopaedic surgery * Petri dish or Petri plate, shallow dish on which biological cul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring Of Fire
The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a tectonic belt of volcanoes and earthquakes. It is about long and up to about wide, and surrounds most of the Pacific Ocean. The Ring of Fire contains between 750 and 915 active or dormant volcanoes, around two-thirds of the world total. The exact number of volcanoes within the Ring of Fire depends on which regions are included. About 90% of the world's earthquakes, including most of its largest, occur within the belt. The Ring of Fire is not a single geological structure. It was created by the subduction of different tectonic plates at convergent boundaries around the Pacific Ocean. These include: the Antarctic plate, Antarctic, Nazca plate, Nazca and Cocos plate, Cocos plates subducting beneath the South American plate; the Pacific plate, Pacific and Juan de Fuca plate, Juan de Fuca plates beneath the North American plate; the Philippine Sea pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSTN
The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists of telephone lines, fiber-optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables interconnected by switching centers, such as central offices, network tandems, and international gateways, which allow telephone users to communicate with each other. Originally a network of fixed-line analog telephone systems, the PSTN is now predominantly digital in its core network and includes terrestrial cellular, satellite, and landline systems. These interconnected networks enable global communication, allowing calls to be made to and from nearly any telephone worldwide. Many of these networks are progressively transitioning to Internet Protocol to carry their telephony tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
