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856 Damghan Earthquake
The Damghan earthquake or the Qumis earthquake occurred on 22 December 856 (242 Anno Hegirae, AH). The earthquake had an estimated Surface-wave magnitude, magnitude of 7.9, and a maximum intensity of X (''Extreme'') on the Mercalli intensity scale. The meizoseismal area (area of maximum damage) extended for about along the southern edge of the eastern Alborz mountains of present-day Iran including parts of Tabaristan and Gorgan. The earthquake's epicenter is estimated to be close to the city of Damghan, which was then the capital of the Persian province of Qumis (region), Qumis. It caused approximately 200,000 deaths and is listed by the United States Geological Survey as the sixth deadliest earthquake in recorded history. This death toll has been debated. Tectonic setting Iran lies within the complex zone of continental collision between the Arabian plate and the Eurasian plate, which extends from the Bitlis-Zagros fold and thrust belt, Zagros belt in the south to the Caucasus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Wave Magnitude
The surface wave magnitude (M_s) scale is one of the Seismic scale#Magnitude scales, magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh wave, Rayleigh surface waves that travel along the uppermost layers of the Earth. This magnitude scale is related to the local magnitude scale proposed by Charles Francis Richter in 1935, with modifications from both Richter and Beno Gutenberg throughout the 1940s and 1950s. It is currently used in People's Republic of China as a guobiao, national standard (GB 17740-1999) for categorising earthquakes. Recorded magnitudes of earthquakes through the mid 20th century, commonly Richter magnitude scale, attributed to Richter, could be either M_s or M_L. Definition The formula to calculate surface wave magnitude is: :M_s = \log_\left(\frac\right)_ + \sigma(\Delta)\,, where A is the maximum particle displacement in surface waves (vector sum of the two horizontal displacements) in micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Collision
In geology, continental collision is a phenomenon of plate tectonics that occurs at Convergent boundary, convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is only known to occur on Earth. Continental collision is not an instantaneous event, but may take several tens of millions of years before the Geologic fault, faulting and Fold (geology), folding caused by collisions stops. Geology of the Himalaya, The collision between Indian plate, India and Eurasian plate, Asia has been going on for about 50 million years already and shows no signs of abating. Collision between East and West Gondwana to form the East African Orogeny, East African Orogen took about 100 million years from beginning (610 Ma) to end (510 Ma). The collision between Gondwana and Laurasia to form Pangea occurred in a relati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Khorasan Province
Khorasan ( ; also transcribed as Khurasan, Xorasan and Khorassan), also called Traxiane during Hellenistic and Parthian Empire, Parthian times, was a Provinces of Iran, province in northeastern Iran until September 2004, when it was divided into three new provinces: North Khorasan, South Khorasan, and Razavi Khorasan. Khorasan historically referred to a much larger area, comprising the east and the northeast of the Persian Empire. The name ''Khorāsān'' is Persian language, Persian and means "where the sun arrives from". The name was first given to the eastern province of Persian Empire, Persia during the Sasanian Empire and was used from the Late Middle Ages in distinction to neighbouring Transoxiana.Svat Soucek''A History of Inner Asia'' Cambridge University, Cambridge University Press, 2000, p.4C. Edmund Bosworth, (2002)'CENTRAL ASIA iv. In the Islamic Period up to the Mongols'''Encyclopaedia Iranica'' (online)C. Edmund Bosworth, (2011)'MĀ WARĀʾ AL-NAHR'''Encyclopaedia I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the Phanerozoic eon. It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today); a proposed third epoch, the Anthropocene, was rejected in 2024 by IUGS, the governing body of the ICS. The Quaternary is typically defined by the Quaternary glaciation, the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused. Research history In 1759 Giovanni Arduino proposed that the geological strata of northern Italy could be divided into four succ ... [...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] |
Journal Of Geophysical Research
The ''Journal of Geophysical Research'' is a peer-reviewed scientific journal. It is the flagship journal of the American Geophysical Union. It contains original research on the physical, chemical, and biological processes that contribute to the understanding of the Earth, Sun, and Solar System. It has seven sections: A (Space Physics), B (Solid Earth), C (Oceans), D (Atmospheres), E (Planets), F (Earth Surface), and G (Biogeosciences). All current and back issues are available online for subscribers. History The journal was originally founded under the name ''Terrestrial Magnetism'' by the American Geophysical Union's president Louis Agricola Bauer in 1896. It was renamed to ''Terrestrial Magnetism and Atmospheric Electricity'' in 1899 and in 1948 it acquired its current name. In 1980, three specialized sections were established: ''A: Space Physics'', ''B: Solid Earth'', and ''C: Oceans''. Subsequently, further sections have been added: ''D: Atmospheres'' in 1984, ''E: Planets' ... [...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] |
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] |
Royal Astronomical Society
The Royal Astronomical Society (RAS) is a learned society and charitable organisation, charity that encourages and promotes the study of astronomy, planetary science, solar-system science, geophysics and closely related branches of science. Its headquarters are in Burlington House, on Piccadilly in London. The society has over 4,000 members, known as fellows, most of whom are professional researchers or postgraduate students. Around a quarter of Fellows live outside the UK. The society holds monthly scientific meetings in London, and the annual National Astronomy Meeting at varying locations in the British Isles. The RAS publishes the scientific journals ''Monthly Notices of the Royal Astronomical Society'', ''Geophysical Journal International'' and ''RAS Techniques and Instruments'', along with the trade magazine ''Astronomy & Geophysics''. The RAS maintains an astronomy research library, engages in public outreach and advises the UK government on astronomy education. The socie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kopet Dag
The Köpet Dag, Kopet Dagh, or Koppeh Dagh (; ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast of the Caspian Sea, stretching northwest-southeast from near the Caspian Sea in the northwest to the Harirud River in the southeast. In the southwest it borders on the parallel eastern endings of the Alborz mountains being together part of the much larger Alpide belt. The highest peak of the range in Turkmenistan is the Mount Rizeh (Kuh-e Rizeh), located at the southwest of the capital Ashgabat and stands at . The highest Iranian summit is Mount Quchan (Kuh-e Quchan) at . Etymology Vambery conjectured that ''köpet'' originates from the Turkmen language where "köp" means "a lot" or "many" and the word "dag" means "mountain" or "peak". He thus translated Köpetdag as "Many mountains (peaks)". He and others noted that in Persian ''koppeh'' means "pile" or "heap", and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apsheron Sill
The Apsheron Sill, Absheron Sill, Apsheron Ridge or Apsheron Threshold is a major northwest-southeast-trending bathymetric high that runs for about across the whole of the Caspian Sea from Baku in Azerbaijan to the Cheleken Peninsula in Turkmenistan. The sill separates the central and southern parts of the Caspian Sea. It is interpreted to be the surface expression of a northeast- dipping subduction zone along which oceanic crust of the South Caspian Basin is being subducted beneath the Central Caspian as part of the complex zone of continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at Convergent boundary, convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroy ... between the Arabian Plate and the Eurasian Plate. References {{Reflist Caspian Sea Geology of Azerbaijan Geology of Turkmenistan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caucasus Mountains
The Caucasus Mountains * * Azerbaijani: , * * * * * * * * * * * is a mountain range at the intersection of Asia and Europe. Stretching between the Black Sea and the Caspian Sea, they are surrounded by the Caucasus region and are home to Mount Elbrus, the highest peak in Europe at above sea level. The Caucasus Mountains include the Greater Caucasus in the north and the Lesser Caucasus in the south. The Greater Caucasus runs west-northwest to east-southeast, from the Western Caucasus on the northeastern shore of the Black Sea to close to Baku on the Caspian Sea, in Azerbaijan. The Lesser Caucasus runs parallel to the Greater about south. The Greater and Lesser Caucasus ranges are connected by the Likhi Range, and to the west and east of the Likhi Range lie the Colchis Plain and the Kur-Araz Lowland respectively. The Meskheti Range is a part of the Lesser Caucasus system. In the southeast, the Aras River separates the Lesser Caucasus from the Tal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
