|
Móðuharðindin
Laki () or Lakagígar (, ''Craters of Laki'') is a volcanic fissure in the western part of Vatnajökull National Park, Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is properly referred to as Lakagígar, while Laki is a mountain that the fissure bisects. Lakagígar is part of a volcanic system centered on the volcano Grímsvötn and including the volcano Þórðarhyrna. It lies between the glaciers of Mýrdalsjökull and Vatnajökull, in an area of fissures that run in a southwest to northeast direction. The system erupted violently over an eight-month period between June 1783 and February 1784 from the Laki fissure and the adjoining volcano Grímsvötn. It poured out an estimated 42 billion tonnes or of basalt lava as well as clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that contaminated the soil, leading to the death of over 50% of Iceland's livestock population, and the destruct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iceland
Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the region's westernmost and most list of countries and dependencies by population density, sparsely populated country. Its Capital city, capital and largest city is Reykjavík, which is home to about 36% of the country's roughly 380,000 residents (excluding nearby towns/suburbs, which are separate municipalities). The official language of the country is Icelandic language, Icelandic. Iceland is on a rift between Plate tectonics, tectonic plates, and its geologic activity includes geysers and frequent Types of volcanic eruptions, volcanic eruptions. The interior consists of a volcanic plateau with sand and lava fields, mountains and glaciers, and many Glacial stream, glacial rivers flow to the sea through the Upland and lowland, lowlands. Iceland i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
India
India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since 2023; and, since its independence in 1947, the world's most populous democracy. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west; China, Nepal, and Bhutan to the north; and Bangladesh and Myanmar to the east. In the Indian Ocean, India is near Sri Lanka and the Maldives; its Andaman and Nicobar Islands share a maritime border with Thailand, Myanmar, and Indonesia. Modern humans arrived on the Indian subcontinent from Africa no later than 55,000 years ago., "Y-Chromosome and Mt-DNA data support the colonization of South Asia by modern humans originating in Africa. ... Coalescence dates for most non-European populations averag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tephra
Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they remain as tephra unless hot enough to fuse into pyroclastic rock or tuff. When a volcano explodes, it releases a variety of tephra including ash, cinders, and blocks. These layers settle on the land and, over time, sedimentation occurs incorporating these tephra layers into the geologic record. Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which Paleoecology, paleoenvironmental or Archaeology, archaeological records can be placed. Often, when a volcano explodes, biological organisms are killed and their remains are buried within the tephra layer. These fossils are later dated by scientists to determine the age of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skaftá
The Skaftá () is a river in South Iceland. It is primarily glacial in origin and has had its course modified by volcanic activity; as a result of both, it often floods because of glacial melting. Course The river's primary source is two subglacial "cauldrons" beneath Skaftájökull, part of the Vatnajökull glacier in the interior of Iceland. It also receives spring-fed water from Langisjór, a lake a short distance to the west from which a tributary called the Útfall runs into the Skaftá. Other tributaries include the North and South Ófaerá, the Grjótá, and the Hellisá. West of Skaftárdalur, a farm named for the river valley, the Skaftá runs over a lava field in many channels, which recombine into three for the remainder of its course to the Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from Spray nozzle, atomizers, smoke, dust, Pesticide, sprayed pesticides, and medical treatments for respiratory illnesses. Several types of atmospheric aerosol have a significant effect on Earth's climate: volcanic, desert dust, sea-salt, that originating from biogenic sources and human-made. Volcanic aerosol forms in the stratosphere after an eruption as droplets of sulfuric acid that can prevail for up to two years, and reflect sunlight, lowering tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Volcanism Program
The Smithsonian Institution's Global Volcanism Program (GVP) documents Earth's volcanoes and their eruptive history during the Quaternary Period of Earth's geologic history, with particular emphasis on volcanic activity during the Holocene Epoch (the last 11,700 years). The mission of the GVP is to document, understand, and disseminate information about global volcanic activity. Global Volcanism Program Database The GVP gathers information and reports on current eruptions from around the world, and maintains a database repository on active volcanoes, their eruptions and their eruption histories. In this way, a global context for the planet's active volcanism is presented. Smithsonian reporting on current volcanic activity dates back to 1968, with the Center for Short-Lived Phenomena (CSLP). The GVP is housed in the Department of Mineral Sciences, part of the National Museum of Natural History, on the National Mall in Washington, D.C. During the early stages of an eruption, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smithsonian Institution
The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums, Education center, education and Research institute, research centers, created by the Federal government of the United States, U.S. government "for the increase and diffusion of knowledge". Founded on August 10, 1846, it operates as a trust instrumentality and is not formally a part of any of the Federal government of the United States#branches, three branches of the federal government. The institution is named after its founding donor, British scientist James Smithson. It was originally organized as the United States National Museum, but that name ceased to exist administratively in 1967. The Smithsonian Institution has historical holdings of over 157 million items, 21 museums, 21 libraries, 14 education and research centers, a zoo, and historical and architectural landmarks, mostly located in Washington, D.C. Additional facilities are located in Maryland, New York (state), New York, and Virg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Explosivity Index
The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest eruptions in history given a magnitude of 8. A value of 0 is given for non-explosive eruptions, defined as less than of tephra ejected; and 8 representing a supervolcanic eruption that can eject (240 cubic miles) of tephra and have a cloud column height of over . The scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI-0, VEI-1 and VEI-2. Classification With indices running from 0 to 8, the VEI associated with an eruption is dependent on how much volcanic materia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effusion
In physics and chemistry, effusion is the process in which a gas escapes from a container through a hole of diameter considerably smaller than the mean free path of the molecules. Such a hole is often described as a ''pinhole'' and the escape of the gas is due to the pressure difference between the container and the exterior. Under these conditions, essentially all molecules which arrive at the hole continue and pass through the hole, since collisions between molecules in the region of the hole are negligible. Conversely, when the diameter is larger than the mean free path of the gas, flow obeys the Sampson flow law. In medical terminology, an effusion refers to accumulation of fluid in an anatomic space, usually without locule, loculation. Specific examples include Subdural hematoma, subdural, otitis media with effusion, mastoid, pericardial effusion, pericardial and pleural effusions. Etymology The word effusion derives from the Latin word, effundo, which means "shed", " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and volcanic gas, gas bubbles. Magma is produced by melting of the mantle (geology), mantle or the Crust (geology), crust in various tectonics, tectonic settings, which on Earth include subduction zones, continental rift (geology), rift zones, mid-ocean ridges and Hotspot (geology), hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal mush, crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by Fractional crystallization (geology), fractional crystallization, contaminati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phreatic Eruption
A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from ) causes near-instantaneous evaporation of water to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens in Washington state, hundreds of steam explosions preceded the 1980 Plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano. Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption. These eruptions occasionally create broad, low-relief craters called '' maars''. Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. Carbon diox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Crater
A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions, molten magma and volcanic gases rise from an underground magma chamber, through a conduit, until they reach the crater's vent, from where the gases escape into the atmosphere and the magma is erupted as lava. A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions, a volcano's magma chamber may empty enough for an area above it to subside, forming a type of larger depression known as a caldera. Geomorphology In most volcanoes, the crater is situated at the top of a mountain formed from the erupted volcanic deposits such as lava flows and tephra. Volcanoes that terminate in such a summit crater are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
