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1998 Balleny Islands Earthquake
In the afternoon of Wednesday 25 March 1998, a very large Moment magnitude scale, magnitude 8.1 earthquake struck a remote area of the Southern Ocean. Its epicentre was located roughly north of George V Land and roughly northwest of the Balleny Islands in Antarctica. Due to the remote location of the earthquake, there were no reports of anyone feeling any shaking or any damage being caused. The event was a complex Intraplate earthquake, intraplate earthquake within the Antarctic Plate. To date it is the largest recorded earthquake in Antarctica, and is the largest recorded earthquake to have been caused by post-glacial rebound. The earthquake occurred in an area which previously had very little seismic activity, and so such a large event was unprecedented in the seismic record. Tectonic setting Nearby to the Balleny Islands is the Macquarie Triple Junction, where the Antarctic Plate, Antarctic, Australian Plate, Australian, and Pacific Plate, Pacific Plates meet. This juncti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where vegetation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mid-ocean Ridge
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin. The production of new seafloor and oceanic lithosphere results from mantle upwelling in response to plate separation. The melt rises as magma at the linear weakness between the separating plates, and emerges as lava, creating new oceanic crust and lithosphere upon cooling. The first discovered mid-ocean ridge was the Mid-Atlantic Ridge, which is a spreading center that bisects the North and South Atlantic basins; hence the origin of the name 'mid-ocean ridge'. Most oceanic spreading centers are not in the middle of their hosting ocean basis but regardless, are traditionally called mid-ocean rid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1998 In Antarctica
1998 was designated as the ''International Year of the Ocean''. Events January * January 6 – The ''Lunar Prospector'' spacecraft is launched into orbit around the Moon, and later finds evidence for frozen water, in soil in permanently shadowed craters near the Moon's poles. * January 11 – Over 100 people are killed in the Sidi-Hamed massacre in Algeria. * January 12 – Nineteen European nations agree to forbid human cloning. * January 17 – The ''Drudge Report'' breaks the story about U.S. President Bill Clinton's alleged affair with Monica Lewinsky, which will lead to the United States House of Representatives, House of Representatives' impeachment of him. February * February 3 – Cavalese cable car disaster (1998), Cavalese cable car disaster: A United States military pilot causes the deaths of 20 people near Trento, Italy, when his low-flying EA-6B Prowler severs the cable of a cable-car. * February 4 – The 5.9 February 1998 Afghanistan earthquake, Afghanistan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1998 Earthquakes
1998 was designated as the ''International Year of the Ocean''. Events January * January 6 – The ''Lunar Prospector'' spacecraft is launched into orbit around the Moon, and later finds evidence for frozen water, in soil in permanently shadowed craters near the Moon's poles. * January 11 – Over 100 people are killed in the Sidi-Hamed massacre in Algeria. * January 12 – Nineteen European nations agree to forbid human cloning. * January 17 – The ''Drudge Report'' breaks the story about U.S. President Bill Clinton's alleged affair with Monica Lewinsky, which will lead to the House of Representatives' impeachment of him. February * February 3 – Cavalese cable car disaster: A United States military pilot causes the deaths of 20 people near Trento, Italy, when his low-flying EA-6B Prowler severs the cable of a cable-car. * February 4 – The 5.9 Afghanistan earthquake shakes the Takhar Province with a maximum Mercalli intensity of VII (''Very strong''). With up to 4, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2004 Tasman Sea Earthquake
The 2004 Tasman Sea earthquake, also known as the 2004 Macquarie Island earthquake, was a very large magnitude 8.1 earthquake which struck a remote area of the southern Tasman Sea in the early morning hours of Friday 24 December 2004. Its epicentre was located roughly northwest of the Auckland Islands of New Zealand, and roughly north of Macquarie Island of Australia. Shaking was reportedly felt as far as Tasmania and the South Island. The event was a complex intraplate earthquake within the Australian Plate, which generated a small tsunami. Tectonic setting The region to the south of New Zealand involves a complex boundary between the Pacific Plate and the Australian Plate. Immediately to the south of the South Island is the Puysegur Trench, where the Australian Plate is subducting obliquely under the Pacific Plate. To the south of this, the Macquarie Fault Zone is a dextral (right lateral) transform boundary. Further south, the Australian Plate is subducting underneath t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Earthquakes In 1998
This is a list of earthquakes in 1998. Only earthquakes of magnitude 6 or above are included, unless they result in damage or casualties, or are notable for some other reason. All dates are listed according to UTC time. Maximum intensities are indicated on the Modified Mercalli intensity scale, and all data are sourced from the United States Geological Survey. By death toll At least 10 dead. By magnitude By month January February March April May June July August September October November December See also * * Lists of 20th-century earthquakes * Lists of earthquakes by year References {{DEFAULTSORT:Earthquakes in 1998 1998 1998 1998 was designated as the ''International Year of the Ocean''. Events January * January 6 – The '' Lunar Prospector'' spacecraft is launched into orbit around the Moon, and later finds evidence for frozen water, in soil in permanently ... 1998 earthquakes 1998-related lists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aftershock
In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms. Distribution of aftershocks Most aftershocks are located over the full area of fault rupture and either occur along the fault plane itself or along other faults within the volume affected by the strain associated with the main shock. Typically, aftershocks are found up to a distance equal to the rupture length away from the fault plane. The pattern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Earthquake Information Center
The National Earthquake Information Center (abbreviated NEIC) is part of the United States Geological Survey (USGS) located on the campus of the Colorado School of Mines in Golden, Colorado. The NEIC has three main missions: * First, the NEIC determines, as rapidly and as accurately as possible, the location and size of all significant earthquakes that occur worldwide. The NEIC disseminates this information immediately to concerned national and international agencies, scientists, critical facilities, and the general public. * Second, the NEIC collects and provides to scientists and to the public an extensive seismic database that serves as a solid foundation for scientific research, principally through the operation of modern digital national and global seismograph networks and through cooperative international agreements. The NEIC is the U.S. national data center and archive for earthquake information. * Third, the NEIC pursues an active research program to improve its ability to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Ice Sheet
The Antarctic ice sheet is one of the two polar ice caps of Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth, with an average thickness of over 2 kilometers. It covers an area of almost and contains of ice. A cubic kilometer of ice weighs approximately 0.92 metric gigatonnes, meaning that the ice sheet weighs ~24,380,000 gigatonnes. It holds approximately 61% of all fresh water on Earth, equivalent to about 58 meters of sea level rise if all the ice were above sea level. In East Antarctica, the ice sheet rests on a major land mass, while in West Antarctica the bed can extend to more than 2,500 m below sea level. Satellite measurements by NASA indicate a still increasing sheet thickness above the continent, outweighing the losses at the edge. The reasons for this are not fully understood, but suggestions include the climatic effects on ocean and atmospheric circulation of the ozone hole, and/or cooler ocean surface temperatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deglaciation
Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice sheet or frozen surface layer, and the resulting exposure of the Earth's surface. The decline of the cryosphere due to ablation can occur on any scale from global to localized to a particular glacier. After the Last Glacial Maximum (ca. 21,000 years ago), the last deglaciation begun, which lasted until the early Holocene. Around much of Earth, deglaciation during the last 100 years has been accelerating as a result of climate change, partly brought on by anthropogenic changes to greenhouse gases. The previous deglaciation took place from approximately 22 ka until 11.5 ka. This occurred when there was an annual mean atmospheric temperature on the earth that increased by roughly 5 °C, which was also accompanied by regional hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of 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 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 geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
