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Pumice Raft
A pumice raft is a floating raft of pumice created by some eruptions of submarine volcanoes or coastal subaerial volcanoes. Biologists suggest that animals and plants have migrated from island to island on pumice rafts. Pumice rafts have unique characteristics such as the highest surface-area-to-volume ratio known for any rock type, long term flotation and beaching in the tidal zone, exposure to a variety of conditions, including dehydration, and an ability to absorb many potentially advantageous elements/compounds. For at least these reasons, astrobiologists have hypothetically proposed pumice rafts as an ideal substrate for the origin of life. Notable examples Pumice rafts drifted to Fiji in 1979 and 1984 from eruptions around Tonga, and some were reportedly wide. Volcanic activity in the South Pacific near Tonga on August 12, 2006 caused the emergence of a new island. The crew of the ''Maiken'', a yacht that had left the northern Tongan islands group of Vava'u in August ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pumice Raft
A pumice raft is a floating raft of pumice created by some eruptions of submarine volcanoes or coastal subaerial volcanoes. Biologists suggest that animals and plants have migrated from island to island on pumice rafts. Pumice rafts have unique characteristics such as the highest surface-area-to-volume ratio known for any rock type, long term flotation and beaching in the tidal zone, exposure to a variety of conditions, including dehydration, and an ability to absorb many potentially advantageous elements/compounds. For at least these reasons, astrobiologists have hypothetically proposed pumice rafts as an ideal substrate for the origin of life. Notable examples Pumice rafts drifted to Fiji in 1979 and 1984 from eruptions around Tonga, and some were reportedly wide. Volcanic activity in the South Pacific near Tonga on August 12, 2006 caused the emergence of a new island. The crew of the ''Maiken'', a yacht that had left the northern Tongan islands group of Vava'u in August ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raoul Island
Raoul Island (''Sunday Island'') is the largest and northernmost of the main Kermadec Islands, south south-west of 'Ata Island of Tonga and north north-east of New Zealand's North Island. It has been the source of vigorous volcanic activity during the past several thousand years that was dominated by dacitic explosive eruptions. The area of the anvil-shaped island, including fringing islets and rocks mainly in the northeast, but also a few smaller ones in the southeast, is . The highest elevation is Moumoukai Peak, at an elevation of . Although Raoul is the only island in the Kermadec group large enough to support settlement, it lacks a safe harbour, and landings from small boats can be made only in calm weather. The island consists of two mountainous areas, one with summits of and , and the other with a summit of , the two separated by a depression which is the caldera of the Raoul volcano. History Evidence from archaeological sites on the northern coast of Raoul Isla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanology
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin word ''vulcan''. Vulcan was the ancient Roman god of fire. A volcanologist is a geologist who studies the eruptive activity and formation of volcanoes and their current and historic eruptions. Volcanologists frequently visit volcanoes, especially active ones, to observe volcanic eruptions, collect eruptive products including tephra (such as ash or pumice), rock and lava samples. One major focus of enquiry is the prediction of eruptions; there is currently no accurate way to do this, but predicting eruptions, like predicting earthquakes, could save many lives. Modern volcanology image:Icelandic tephra.JPG, Volcanologist examining tephra horizons in south-central Iceland. In 1841, the first volcanological observatory, the Vesuvius Observatory, was founded in the Kingdom o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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 pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Balloons
A lava balloon is a gas-filled bubble of lava that floats on the sea surface. It can be up to several metres in size. When it emerges from the sea, it is usually hot and often steaming. After floating for some time it fills with water and sinks again. Lava balloons can form in lava flows entering the sea and at volcanic vents, but they are not common. They have been observed in the Azores, Canary Islands, Hawaii, Japan, Mariana Islands and Mexico. Apparently, they are generated when gases trapped within magma form large bubbles that eventually rise to the sea surface. In the Canary Islands, balloons containing sediments were used to infer the age of the basement on which the volcano is constructed; these sediments were also at first misinterpreted as evidence of an impending large explosive eruption. Appearance Lava balloons are gas-filled bubbles surrounded by a crust formed by lava; their gas content allows them to float on the sea surface. Observed sizes range from at El H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floating Island
A floating island is a mass of floating aquatic plants, mud, and peat ranging in thickness from several centimeters to a few meters. Floating islands are a common natural phenomenon that are found in many parts of the world. They exist less commonly as an artificial phenomenon. Floating islands are generally found on marshlands, lakes, and similar wetland locations, and can be many hectares in size. Natural occurrences Sometimes referred to as ''tussocks'', ''floatons'', or ''suds'', natural floating islands are composed of vegetation growing on a buoyant mat of plant roots or other organic detritus. In aquatic regions of Northwestern Europe several hundred hectares or thousand acres of floating meadows (German ''Schwingrasen'', Dutch ''trilveen'') have been preserved, which are partly used as agricultural land, partly as nature reserves. They typically occur when growths of cattails, bulrush, sedge, and reeds extend outward from the shoreline of a wetland area. As the wate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curacoa Volcano
Curacoa is a submarine volcano located south of the Curacoa Reef in northern Tonga. The reef is 24fm North of Tafahi in the Niua Islands. Eruptions were observed in 1973 and 1979 from two separate vents. The 1973 eruption produced a large raft of dacitic pumice, and had a volcanic explosivity index (VEI) of 3. See also *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 t ... References Volcanoes of Tonga Submarine volcanoes Active volcanoes {{Tonga-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phantom Island
A phantom island is a purported island which was included on maps for a period of time, but was later found not to exist. They usually originate from the reports of early sailors exploring new regions, and are commonly the result of navigational errors, mistaken observations, unverified misinformation, or deliberate fabrication. Some have remained on maps for centuries before being "un-discovered." Unlike lost lands, which are claimed (or known) to have once existed but to have been swallowed by the sea or otherwise destroyed, a phantom island is one that is claimed to exist contemporaneously, but later found not to have existed in the first place (or found not to be an island, as with the Island of California). Examples Some may have been purely mythical, such as the Isle of Demons near Newfoundland, which may have been based on local legends of a haunted island. The far-northern island of Thule was reported to exist by 4th century BCE Greek explorer Pytheas, but informati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandy Island, New Caledonia
Sandy Island (sometimes labelled in French , and in Spanish ) is a non-existent island that was charted for over a century as being located near the French territory of New Caledonia between the Chesterfield Islands and Nereus Reef in the eastern Coral Sea. The island was included on many maps and nautical charts from as early as the late 19th century. It was removed from French hydrographic charts in 1974. The island gained wide media and public attention in November 2012 when the R/V ''Southern Surveyor'', an Australian research ship, passed through the area and "undiscovered" it. The island was quickly removed from many maps and data sets, including those of the National Geographic Society and Google Maps. History On 14–15 September 1774, Captain James Cook charted a "Sandy I." snaking between 19°–20° S latitudes and 163°50'–164°15' E longitude off the tip of New Caledonia. The associated map, titled "Chart of Discoveries made in the South Paci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kingdom Of Tonga
Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesia, Polynesian country and archipelago. The country has List of islands and towns in Tonga, 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 Islands, 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 culture, Lapita civilization, Tonga's Polynesian settlers gradually evolved a distinct and strong ethnic identity, Tongan language, lan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late (Tonga)
Late Island is an uninhabited volcanic island southwest of Vavaʻu in the kingdom of Tonga. Geography The small, 6-km-wide circular island of Late, lying along the Tofua volcanic arc about 55 km WSW of the island of Vavau, contains a 400-m-wide, 150-m-deep summit crater with an ephemeral lake. The largely submerged basaltic andesite to andesitic volcano rises 1500 m from the sea floor, with its conical summit reaching 540 m above sea level. Cinder cones are found north of the summit crater, west and north of a semicircular plateau 100–150 m below the summit, and on the NW coast. A graben-like structure on the NE flank contains two large pit craters, the lower of which is partially filled by a saltwater lake. Only two eruptions have occurred in historical time, both from NE-flank craters, which produced explosive activity and possible lava flows in 1790 and 1854. History It was discovered by Spanish naval officer Francisco Mourelle de la Rúa on 27 February 1781, on board ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2012 Kermadec Islands Eruption
The 2012 Kermadec Islands eruption was a major undersea volcanic eruption that was produced by the previously little-known Havre Seamount near the L'Esperance and L'Havre Rocks in the Kermadec Islands of New Zealand. The large volume of low density pumice produced by the eruption accumulated as a large area of floating pumice, a ''pumice raft,'' that was originally covering a surface of , spread to a continuous float of between and within three months dispersed to an area of more than twice the size of New Zealand.Website of the expedition ''Mesh'' The thickness of the raft may initially have been as high as and was reduced to around within a month. Three months after the eruption, the mass had dispersed into very dilute rafts and ribbons of floating pumice clasts. Most pumice clasts became waterlogged and sank to the sea floor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
