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Home Reef
Home Reef is a volcanic island atop a submarine volcano in Tonga. It is located southwest of Vava'u, between the islands of Kao and Late along the Tofua volcanic arc. The island is ephemeral, and has been repeatedly built and eroded by successive eruptions in 1852, 1857, 1984, 2006, and 2022. An eruption in 1984 built a small, temporary island , as well as pumice rafts which washed up as far away as Fiji and Australia. The island washed away within a few months. After a volcanic eruption started on 8 August 2006, Home Reef emerged as an island; that eruption also spewed into Tongan waters large amounts of floating pumice, which swept across to Fiji about to the west of the new island. In October 2006, it reached almost the same size as it did in 1984, when it was about . The island was first seen by the crew of a yacht, who recorded its emergence in their blog. The eruptions produced extensive rafts of pumice, which drifted northeast from the new island. The pumice rafts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Spaceborne Thermal Emission And Reflection Radiometer
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a Japanese remote sensing instrument onboard the Terra satellite launched by NASA in 1999. It has been collecting data since February 2000. ASTER provides high-resolution images of Earth in 14 different bands of the electromagnetic spectrum, ranging from visible to thermal infrared light. The resolution of images ranges between 15 and 90 meters. ASTER data is used to create detailed maps of surface temperature of land, emissivity, reflectance, and elevation. In April 2008, the SWIR detectors of ASTER began malfunctioning and were publicly declared non-operational by NASA in January 2009. All SWIR data collected after 1 April 2008 has been marked as unusable. The ASTER Global Digital Elevation Model (GDEM) is available at no charge to users worldwide via electronic download. As of 2 April 2016, the entire catalogue of ASTER image data became publicly available online at no cost. It can be downloaded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker vesicle walls, and being dark colored and denser.Jackson, J.A., J. Mehl, and K. Neuendorf (2005) ''Glossary of Geology'' American Geological Institute, Alexandria, Virginia. 800 pp. McPhie, J., M. Doyle, and R. Allen (1993) ''Volcanic Textures A guide to the interpretation of textures in volcanic rocks'' Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart, Tasmania..198 pp. Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the solubi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanoes Of Tonga
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submarine Volcanoes
Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth.Martin R. Speight, Peter A. Henderson, "Marine Ecology: Concepts and Applications", John Wiley & Sons, 2013. . Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The total number of submarine volcanoes is estimated to be over 1 million (most are now extinct) of which some 75,000 rise more than 1 km above the seabed. Only 119 submarine volcanoes in Earth's oceans and seas are known to have erupted during the last 11,700 years. Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes. Eff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Volcanoes
An active volcano is a volcano which is either erupting or is likely to erupt in the future. An active volcano which is not currently erupting is known as a dormant volcano. Overview Tlocene Epoch. Most volcanoes are situated on the Pacific Ring of Fire. An estimated 500 million people live near active volcanoes. ''Historical time'' (or recorded history) is another timeframe for ''active''. However, the span of recorded history differs from region to region. In China and the Mediterranean, it reaches back nearly 3,000 years, but in the Pacific Northwest of the United States and Canada, it reaches back less than 300 years, and in Hawaii and New Zealand it is only around 200 years. The incomplete ''Catalogue of the Active Volcanoes of the World'', published in parts between 1951 and 1975 by the International Association of Volcanology, uses this definition, by which there are more than 500 active volcanoes. , the Smithsonian Global Volcanism Program recognizes 560 volcanoes with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Recently Born Islands
Below is a list of new islands created since the beginning of the 20th century by volcanism, erosion, glacial retreat, or other mechanisms. One of the most famous new volcanic islands is the small island of Surtsey, located in the Atlantic Ocean south of Iceland. It first emerged from the ocean surface in 1963. Two years later, Surtsey was declared a nature reserve for the study of ecological succession; plants, insects, birds, seals, and other forms of life have since established themselves on the island. Another noted new island is Anak Krakatau (the so-called "child of Krakatoa", which formed in the flooded caldera of that notorious volcano in Indonesia), which emerged only in 1930. Ample rainforests have grown there, although they are often destroyed by frequent eruptions. A population of many wild animals, including insects, birds, humanborne rats, and even monitor lizards, have also settled there. Didicas Volcano off the northern coast of Luzon Island in the Philippin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Volcanoes In Tonga ...
This is a list of active and extinct volcanoes in Tonga. References * See especiallFigure 1 * D. Stanley; South Pacific handbook * Government of Tonga, official 1962 land survey {{reflist Tonga Volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dacite Pumice (August 2006 Eruption Of Home Reef Volcano, Tofua Volcanic Arc, Central Tonga Islands, Sw Pacific Ocean; Collected At Beach In Northern Fiji Islands) 2
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained ( aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz. Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline tholeiitic and calc-alkaline magma series. Composition Dacite consists mostly of plagioclase feldspar and quartz with biotite, hornblende, and pyroxene (augite or enstatite). The quartz appears as rounded, corroded phenocrysts, or as an element of the ground-mass. The plagioclase in dacite ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, and when abundant gives rise to rocks that form transitions to the rhyolites. The relative proportions of feldspa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonga Geological Services
Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in the southern Pacific Ocean. As of 2021, according to Johnson's Tribune, Tonga has a population of 104,494, 70% of whom reside on the main island, Tongatapu. The country stretches approximately north-south. It is surrounded by Fiji and Wallis and Futuna (France) to the northwest; Samoa to the northeast; New Caledonia (France) and Vanuatu to the west; Niue (the nearest foreign territory) to the east; and Kermadec (New Zealand) to the southwest. Tonga is about from New Zealand's North Island. First inhabited roughly 2,500 years ago by the Lapita civilization, Tonga's Polynesian settlers gradually evolved a distinct and strong ethnic identity, language, and culture as the Tongan people. They were quick to establish a powerful footi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Crater Lake
A volcanic crater lake is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption. Formation Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars fill medium-sized craters where an eruption deposited debris around a vent. Crater lakes form as the created depression, within the crater rim, is filled by water. The water may come from precipitation, groundwater circulation (often hydrothermal fluids in the case of volcanic craters) or melted ice. Its level rises until an equilibrium is reached between the rates of incoming and outgoing water. Sources of water loss singly or together may include evaporation, subsurface seepage, and, in places, surface leakage or overflow when the lake level reaches the lowest point on its rim. At such a saddle location, the upper portion of the lake is contained only by its adjacent natural volcanic dam; continued leakage through or surface outflow ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqua (satellite)
Aqua (EOS PM-1) is a NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System (EOS) preceded by Terra (launched 1999) and followed by Aura (launched 2004). The name "Aqua" comes from the Latin word for water. The satellite was launched from Vandenberg Air Force Base on May 4, 2002, aboard a Delta II rocket. Aqua operated in a sun-synchronous orbit as the third in the satellite formation called the " A Train" with several other satellites (OCO-2, the Japanese GCOM W1, PARASOL, CALIPSO, CloudSat, and Aura) for most of its first 20 years; but in January 2022 Aqua left the A-Train (as CloudSat, CALIPSO and PARASOL had already done) when, due to its fuel limitations, it transitioned to a free-drift mode, wherein its equatorial crossing time is slowly drifting to later times, from its tightly controlled orbit. Mission Aqua is one of NASA's missions for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blogger (service)
Blogger is an American online content management system founded in 1999 which enables multi-user blogs with time-stamped entries. Pyra Labs developed it before being acquired by Google in 2003. Google hosts the blogs, which can be accessed through a subdomain of blogspot.com. Blogs can also be accessed from a user-owned Domain name, custom domain (such as www.example.com) by using Domain Name System, DNS facilities to direct a domain to Google's servers. A user can have up to 100 blogs or websites per account. Google Blogger also enabled users to publish blogs and websites to their own web hosting server via File Transfer Protocol, FTP until May 1, 2010. All such blogs and websites had to be redirected to a blogspot.com subdomain or point their own domain to Google's servers via Domain Name System, DNS. Google Blogger has a wide international user base and is available in more than 60 languages, despite its decline in popularity in the United States. History Pyra Labs launched ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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