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2006 Yogyakarta Earthquake
The 2006 Yogyakarta earthquake (also known as the Bantul earthquake) occurred at with a moment magnitude of 6.4 and a maximum MSK intensity of VIII (''Damaging''). Several factors led to a disproportionate amount of damage and number of casualties for the size of the shock, with more than 5,700 dead, tens of thousands injured, and financial losses of Rp 29.1 trillion ( $3.1 billion). With limited effects to public infrastructure and lifelines, housing and private businesses bore the majority of damage (the 9th-century Prambanan Hindu temple compound was also affected), and the United States' National Geophysical Data Center classified the total damage from the event as extreme. Although Indonesia experiences very large, great, and giant thrust earthquakes offshore at the Sunda Trench, this was a large strike-slip event that occurred on the southern coast of Java near the city of Yogyakarta. Mount Merapi lies nearby, and during its many previous historical eruptions, large v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time In Indonesia
The Indonesian Archipelago geographically stretches across four time zones from UTC+06:00 in Aceh to UTC+09:00 in Papua. However, the Indonesian government recognises only three time zones in its territory, namely: *Western Indonesia Time (WIB) — seven hours ahead ( UTC+07:00) of the Coordinated Universal Time (UTC); *Central Indonesia Time (WITA) — eight hours ahead ( UTC+08:00) of UTC; *Eastern Indonesia Time (WIT) — nine hours ahead ( UTC+09:00) of UTC. The boundary between the Western and Central time zones was established as a line running north between Java and Bali through the provincial boundaries of West and Central Kalimantan. The border between the Central and Eastern time zones runs north from the eastern tip of Indonesian Timor to the eastern tip of Sulawesi. Daylight saving time (DST) is no longer observed anywhere in Indonesia. Current usage In Indonesia, the keeping of standard time is divided into three time zones: These time zones were first ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as . Stratovolcanoes are sometimes called composite volcanoes because of their composite stratified structure, built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volcano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wadati–Benioff Zone
A Wadati–Benioff zone (also Benioff–Wadati zone or Benioff zone or Benioff seismic zone) is a planar zone of seismicity corresponding with the down-going slab in a subduction zone. Differential motion along the zone produces numerous earthquakes, the foci of which may be as deep as about . The term was named for the two seismologists, Hugo Benioff of the California Institute of Technology and Kiyoo Wadati of the Japan Meteorological Agency, who independently discovered the zones. Wadati–Benioff zone earthquakes develop beneath volcanic island arcs and continental margins above active subduction zones. They can be produced by slip along the subduction thrust fault or slip on faults within the downgoing plate, as a result of bending and extension as the plate is pulled into the mantle. The deep-focus earthquakes along the zone allow seismologists to map the three-dimensional surface of a subducting slab of oceanic crust and mantle. Discovery In 1949, Hugo Benioff intro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction Zone
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate 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 the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of the den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasian Plate
The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and the area east of the Chersky Range in eastern Siberia. It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge. The eastern edge is a boundary with the North American Plate to the north and a boundary with the Philippine Sea Plate to the south and possibly with the Okhotsk Plate and the Amurian Plate. The southern edge is a boundary with the African Plate to the west, the Arabian Plate in the middle and the Indo-Australian Plate to the east. The western edge is a divergent boundary with the North American Plate forming the northernmost part of the Mid-Atlantic Ridge, which is straddled by Iceland. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell, the 17 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indo-Australian Plate
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian and the Australian Plates approximately 43 million years ago. The fusion happened when the mid-ocean ridge in the Indian Ocean, which separated the two plates, ceased spreading. Regions India, Australia, New Guinea, Tasmania, New Zealand, and New Caledonia are all fragments of the ancient supercontinent of Gondwana. As the ocean floor broke apart, these land masses fragmented from one another, and for a time these centers were thought to be dormant and fused into a single plate. However, research in the early 21st century indicates plate separation of the Indo-Australian Plate may have already occurred. Characteristics The eastern side of the plate is the convergent boundary with the Pacific plate. The Pacific plate sinks below the Au ... [...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 bring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunda Shelf
Geologically, the Sunda Shelf is a south-eastern extension of the continental shelf of Mainland Southeast Asia. Major landmasses on the shelf include the Bali, Borneo, Java, Madura, and Sumatra, as well as their surrounding smaller islands. It covers an area of approximately 1.85 million km2.va Bemmelen, R.W. (1949). ''The Geology of Indonesia.'' Vol. IA'': General Geology of Indonesia and Adjacent Archipelagoes.'' Matinus Nithoff, The Hague, 723 pp. Sea depths over the shelf rarely exceed 50 metres and extensive areas are less than 20 metres resulting in strong bottom friction and strong tidal friction. Steep undersea gradients separate the Sunda Shelf from the Philippines, Sulawesi, and the Lesser Sunda Islands. Definition Biogeographically, Sundaland is a term for the region of Southeastern Asia which encompasses these areas of the Asian continental shelf that were exposed during the last ice age. Sundaland included the Malay Peninsula on the Asian mainland, as well as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indonesian Archipelago
The islands of Indonesia, also known as the Indonesian Archipelago ( id, Kepulauan Indonesia) or Nusantara, may refer either to the islands comprising the country of Indonesia or to the geographical groups which include its islands. History The exact number of islands comprising Indonesia varies among definitions and sources. According to the Law No 9/1996 on Maritime Territory of Indonesia, of 17,508 officially listed islands within the territory of the Republic of Indonesia. According to a geospatial survey conducted between 2007 and 2010 by the National Coordinating Agency for Survey and Mapping (Bakorsurtanal), Indonesia has 13,466 islands. However, according to earlier survey in 2002 by National Institute of Aeronautics and Space (LAPAN), the Indonesian archipelago has 18,307 islands, and according to the CIA ''World Factbook'', there are 17,508 islands. The discrepancy of the numbers of Indonesian islands was because that the earlier surveys include " tidal islands" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Types Of Volcanic Eruptions
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions: * Magmatic eruptions are the most well-observed type of eruption. They involve the decompression of gas within magma that propels it forward. * Phreatic eruptions are driven by the superheating of steam due to the close proximity of magma. This type exhibits no magmatic release, instead causing the granulation of existing rock. * Phreatomagmatic eruptions are driven by the direct interaction of magma and water, as opposed to phreatic erup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate Tectonics
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago. The model builds on the concept of ''continental drift'', an idea developed during the first decades of the 20th century. Plate tectonics came to be generally accepted by geoscientists after seafloor spreading was validated in the mid to late 1960s. Earth's lithosphere, which is the rigid outermost shell of the planet (the crust and upper mantle), is broken 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: '' convergent'', '' divergent'', or ''transform''. Earthquakes, volcanic activity, mountain-building, and oceanic tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
