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2020 Aegean Sea Earthquake
An earthquake with a moment magnitude of 7.0 occurred on 30 October 2020 about northeast of the Greek island of Samos. Although Samos was closest to the epicentre, it was the large Turkish city İzmir, northeast that was heavily affected—more than 700 residential and commercial structures were seriously damaged or destroyed. One hundred and seventeen people died in İzmir Province while an additional 1,034 were injured. In Greece, there were two fatalities and 19 injured. The earthquake is the List of earthquakes in 2020, deadliest in the year 2020, and the third major earthquake to strike Turkey that year. It generated an unusually large tsunami. The event is called the Samos earthquake by the International Seismological Centre. Tectonic setting The Aegean Sea is a seismically active region with complex plate tectonics interaction both within and surrounding the Aegean Sea plate. The region has several major plate boundary including the North Anatolian Fault which runs t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Ground Acceleration
Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an wikt:accelerogram, accelerogram at a site during a particular earthquake. Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. Horizontal PGAs are generally larger than those in the vertical direction but this is not always true, especially close to large earthquakes. PGA is an important parameter (also known as an intensity measure) for earthquake engineering, The design basis earthquake ground motion (DBEGM) is often defined in terms of PGA. Unlike the Richter magnitude scale, Richter and Moment magnitude scale, moment magnitude scales, it is not a measure of the total seismic scales#Magnitude and intensity, energy (magnitude, or size) of an earthquake, but rather of how much the earth shake ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Anatolian Fault
The North Anatolian Fault (NAF; ) is an active right-lateral strike-slip fault in northern Anatolia, and is the transform boundary between the Eurasian plate and the Anatolian sub-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 1200−1500 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 west. Seismologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hellenic Subduction Zone
The Hellenic subduction zone (HSZ) is the convergent boundary between the African plate and the Aegean Sea plate, where oceanic crust of the African continent is being subducted north–northeastwards beneath the Aegean. The southernmost and shallowest part of the zone is obscured beneath the deformed thick sedimentary sequence that forms the Mediterranean Ridge accretionary complex. It has a well-defined Wadati–Benioff zone of seismicity, which demonstrates the relatively shallow dip of its southern part, which increases markedly to the north of the non-volcanic part of the Hellenic arc. The descending slab has been imaged using seismic tomography down to the top of the mantle transition zone at 410 km depth. Surface expression When the subduction zone was originally identified in the 1970s, it was thought that the Hellenic trench was the surface expression of the HSZ. Once the Mediterranean Ridge was recognised as an accretionary complex, the majority of geoscienti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
365 Crete Earthquake
The 365 Crete earthquake occurred at about sunrise on 21 July 365 in the Eastern Mediterranean, with an assumed epicentre near Crete. Geologists today estimate the undersea earthquake to have been a moment magnitude 8.5 or higher. It caused widespread destruction in the central and southern Diocese of Macedonia (modern Greece), Africa Proconsularis (northern Libya), Egypt, Cyprus, Sicily, and Hispania (Spain). On Crete, nearly all towns were destroyed. The earthquake was followed by a tsunami which devastated the southern and eastern coasts of the Mediterranean, particularly Libya, Alexandria, and the Nile Delta, killing thousands and hurling ships inland. Ammianus Marcellinus"Res Gestae" 26.10.15–19 The quake left a deep impression on the late antique mind, and numerous writers of the time referred to the event in their works. Geological evidence Recent (2001) geological studies view the 365 Crete earthquake in connection with a clustering of major seismic activity in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megathrust Earthquake
Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (''Mw'') that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area. As a result, megathrust earthquakes often generate tsunamis that are considerably more destructive than the earthquakes themselves. Teletsunamis can cross ocean basins to devastate areas far from the original earthquake. Terminology and mechanism The term ''megathrust'' refers to an extremely large thrust fault, typically formed at the plate interface along a subduction zo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. Subduction is possible because the cold and rigid oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle. Once initiated, stable subduction is driven mostly by the negative buoyancy of the dense subducting lithosphere. The down-going slab sinks into the mantle largely under its own ... [...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] |
American Geophysical Union
The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, Atmospheric science, atmospheric, Oceanography, ocean, Hydrology, hydrologic, Astronomy, space, and Planetary science, planetary scientists and enthusiasts that according to their website includes 130,000 people (not members). AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international fields within the Earth and space sciences. The geophysical sciences involve four fundamental areas: atmospheric sciences, atmospheric and ocean sciences; solid-Earth sciences; hydrologic sciences; and space sciences. The organization's headquarters is located on Florida Avenue in Washington, D.C. History The AGU was established in December 1919 by the United States National Research Council, National Research Council (NRC) to represent the United States in the International Union of Geodesy and Geophysics (IUGG), and its first chairman w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2020 Elazığ Earthquake
The 2020 Elazığ earthquake occurred at 20:55 local time (17:55 UTC) on 24 January in Turkey. The magnitude of the earthquake was determined to be 6.7 . The earthquake's epicentre was close to the town of Sivrice in Elazığ Province and felt in the neighbouring provinces of Diyarbakır, Malatya and Adıyaman, and the neighbouring countries of Armenia, Syria and Iran. Kandilli Observatory reported the magnitude of the earthquake as 6.5 . A total of 41 people were killed and more than 1,600 were injured. Tectonic setting Most of Turkey lies on the Anatolian Plate, which is being forced westwards by the collision between the Arabian plate and the Eurasian plate. This westward movement is accommodated by two large strike-slip fault zones, the west–east trending right lateral North Anatolian Fault in the north of the country and the SW-NE trending left lateral East Anatolian Fault towards the south-east. Movement on these two faults has been responsible for many large and da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transform Fault
A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction, subduction zone. A transform fault is a special case of a ''strike-slip fault'' that also forms a plate boundary. Most such faults are found in oceanic crust, where they accommodate the lateral offset between segments of Divergent boundary, divergent boundaries, forming a zigzag pattern. This results from oblique seafloor spreading where the direction of motion is not perpendicular to the trend of the overall divergent boundary. A smaller number of such faults are found on land, although these are generally better-known, such as the San Andreas Fault and North Anatolian Fault. Nomenclature Transform boundaries are also known as conservative plate boundaries because they involve no addit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Anatolian Fault
The East Anatolian Fault (EAF; ) is a ~700 km long major strike-slip fault zone running from eastern to south-central Turkey. It forms the transform type tectonic boundary between the Anatolian sub-plate and the northward-moving Arabian plate. The difference in the relative motions of the two plates is manifest in the left lateral motion along the fault. The East and North Anatolian faults together accommodate the westward motion of the Anatolian sub-plate as it is squeezed out by the ongoing collision between the Arabian plate and the Eurasian plate. The East Anatolian Fault runs in a northeasterly direction, starting from the Maraş triple junction at the northern end of the Dead Sea Transform, and ending at the Karlıova triple junction where it meets the North Anatolian Fault. Another strand of the fault exists north of the main strand known as the Sürgü–Misis Fault System. Discovery In 1963, geologists published descriptions about a fault structure near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
