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Lava Lake
Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometimes referred to as ''frozen lava lakes''). Formation Lava lakes can form in three ways: *from one or more vents in a crater that erupts enough lava to partially fill the crater; or *when lava pours into a crater or broad depression and partially fills the crater; or *atop a new vent that erupts lava continuously for a period of several weeks or more and slowly builds a crater progressively higher than the surrounding ground. Behaviors Lava lakes occur in a variety of volcanic systems, ranging from the basaltic Erta Ale lake in Ethiopia and the basaltic andesite volcano of Villarrica, Chile, to the unique phonolitic lava lake at Mt. Erebus, Antarctica. Lava lakes have been observed to exhibit a range of behaviours. A "constantly circulat ... [...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] |
Kīlauea
Kīlauea ( , ) is an active shield volcano in the Hawaiian Islands. Located along the southeastern shore of the Big Island of Hawaii, the volcano is between 210,000 and 280,000 years old and emerged above sea level about 100,000 years ago. Historically, it is the most active of the five volcanoes that together form Hawaii island. Kīlauea is also one of the most active volcanoes on Earth, and the most recent and currently ongoing eruption began on September 29, 2021, when several vents began to erupt lava within Halemaʻumaʻu, a pit crater in the volcano's summit caldera. Kīlauea is the second-youngest product of the Hawaiian hotspot and the current eruptive center of the Hawaiian–Emperor seamount chain. Because it lacks topographic prominence and its activities historically coincided with those of Mauna Loa, Kīlauea was once thought to be a satellite of its much larger neighbor. Structurally, Kīlauea has a large, fairly recently formed caldera at its summit and two ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saunders Island, South Sandwich Islands
Saunders Island is a crescent-shaped island long, lying between Candlemas Island and Montagu Island in the South Georgia and the South Sandwich Islands, South Sandwich Islands, a British Overseas Territory in the southern Atlantic Ocean. It is a volcanic island composed of an active stratovolcano, Mount Michael. History Saunders Island was discovered in 1775 by Captain James Cook, who named it for Charles Saunders (admiral), Sir Charles Saunders, First Lord of the Admiralty. It was charted in greater detail by Fabian Gottlieb von Bellingshausen, Bellingshausen in 1819, and in 1930 by Discovery Investigations (DI) personnel aboard RRS Discovery II, ''Discovery II''. The island was surveyed in 1964 by . Polar explorer Ernest Shackleton sometimes misspells the island's name as "Sanders Island" in his book ''s:South: the story of Shackleton's last expedition, 1914-1917, South''. Features The centre of the island is Mount Michael, a volcano known to have erupted explosively in 1819 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Michael
Mount Michael ( es, Monte Miguel) is an active volcanic mountain, 843 m, surmounting Saunders Island in the South Sandwich Islands, a British Overseas Territory The British Overseas Territories (BOTs), also known as the United Kingdom Overseas Territories (UKOTs), are fourteen dependent territory, territories with a constitutional and historical link with the United Kingdom. They are the last remna ... in the southern Atlantic Ocean. It is one of the few volcanoes in an overseas territory of the United Kingdom. The island was discovered by a British expedition under Cook in 1775, but the mountain was presumably first charted in 1820 by a Russian expedition under Bellingshausen. Recharted in 1930 by DI personnel on the Commander W.M. Carey, Royal Navy, captain of the '' Discovery II'' at the time of the survey. Persistent lava lake In 2019, it was discovered that Mount Michael has a persistent lava lake, a rare phenomenon which is known to occur at only eight vol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Masaya Volcano
Masaya ( es, Volcán Masaya) is a caldera located in Masaya, Nicaragua, 20 km south of the capital Managua. It is Nicaragua's first and largest national park, and one of 78 protected areas of Nicaragua. The complex volcano is composed of a nested set of calderas and craters, the largest of which is Las Sierras shield volcano and caldera. Within this caldera lies a sub-vent, which is Masaya Volcano ''sensu stricto''. The vent is a shield type composing of basaltic lavas and tephras and includes a summit crater. This hosts Masaya caldera, formed 2,500 years ago by an 8-km³ basaltic ignimbrite eruption. Inside this caldera a new basaltic complex has grown from eruptions mainly on a semi-circular set of vents that include the Masaya and Nindiri cones. The latter host the pit craters of Masaya, Santiago, Nindiri and San Pedro. Observations in the walls of the pit craters indicate that there have been several episodes of cone and pit crater formation. Masaya continu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state geographically located within the tropics. Hawaii comprises nearly the entire Hawaiian archipelago, 137 volcanic islands spanning that are physiographically and ethnologically part of the Polynesian subregion of Oceania. The state's ocean coastline is consequently the fourth-longest in the U.S., at about . The eight main islands, from northwest to southeast, are Niihau, Kauai, Oahu, Molokai, Lānai, Kahoolawe, Maui, and Hawaii—the last of these, after which the state is named, is often called the "Big Island" or "Hawaii Island" to avoid confusion with the state or archipelago. The uninhabited Northwestern Hawaiian Islands make up most of the Papahānaumokuākea Marine National Monument, the United States' largest protected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawaii (island)
Hawaii ( ; haw, Hawaii ) is the List of islands of the United States by area, largest island in the United States, located in the U.S. state, state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of High island, volcanic islands in the Pacific Ocean, North Pacific Ocean. With an area of , it has 63% of the Hawaiian archipelago's combined landmass. However, it has only 13% of Hawaiʻi's population. The island of Hawaiʻi is the third largest island in Polynesia, behind the two main List of islands of New Zealand, islands of New Zealand. The island is often referred to as the Island of Hawaii or Hawaii Island to distinguish it from the state. It is also referred to as the Big Island. Administratively, the island is coextensive with Hawaii County, Hawaii, Hawaii County. As of the 2020 United States census, 2020 census, the population was 200,629. The county seat and largest town is Hilo, Hawaii, Hilo. There are no Municipal corporation, incorporated cities i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ross Island
Ross Island is an island formed by four volcanoes in the Ross Sea near the continent of Antarctica, off the coast of Victoria Land in McMurdo Sound. Ross Island lies within the boundaries of Ross Dependency, an area of Antarctica claimed by New Zealand. History Discovery Sir James Ross discovered it in 1840, and it was later named in honour of him by Robert F. Scott. Ross Island was the base for many of the early expeditions to Antarctica. It is the southernmost island reachable by sea. Huts built by Scott's and Shackleton's expeditions are still standing on the island, preserved as historical sites. Today Ross Island is home to New Zealand's Scott Base, and the largest Antarctic settlement, the U.S. Antarctic Program's McMurdo Station. Greenpeace established World Park Base on the island and ran it for five years, from 1987 to 1992. Geography Because of the persistent presence of the ice sheet, the island is sometimes taken to be part of the Antarctic mainland. Its are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vanuatu
Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of northern Australia, northeast of New Caledonia, east of New Guinea, southeast of the Solomon Islands, and west of Fiji. Vanuatu was first inhabited by Melanesian people. The first Europeans to visit the islands were a Spanish expedition led by Portuguese navigator Fernandes de Queirós, who arrived on the largest island, Espíritu Santo, in 1606. Queirós claimed the archipelago for Spain, as part of the colonial Spanish East Indies, and named it . In the 1880s, France and the United Kingdom claimed parts of the archipelago, and in 1906, they agreed on a framework for jointly managing the archipelago as the New Hebrides through an Anglo-French condominium. An independence movement arose in the 1970s, and the Republic of Vanuatu was fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambrym
Ambrym is a volcanic island in Malampa Province in the archipelago of Vanuatu. Volcanic activity on the island includes lava lakes in two craters near the summit. Etymology Ambrym (also known as ''Ambrin'', ''"ham rim"'' in the Ranon language) was allegedly named by Captain Cook, who is said to have anchored off there in 1774. In fact, his expedition never touched Ambrym. Geography Located near the center of the Vanuatuan archipelago, Ambrym is roughly triangular in shape, about wide. With of surface area, it is the fifth largest island in the country. The summit at the centre of the island is dominated by a desert-like caldera, which covers an area of . With the exception of human settlements, the rest of the island is covered by a dense jungle. Important Bird Area The western part of the island, comprising 17,605 ha of forest, together with gardens around habitation, has been recognised as an Important Bird Area (IBA) by BirdLife International because it suppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalescence (physics)
Coalescence is the process by which two or more droplets, bubbles or particles merge during contact to form a single daughter droplet, bubble or particle. It can take place in many processes, ranging from meteorology to astrophysics. For example, it is seen in the formation of raindrops as well as planetary and star formation. In meteorology, its role is crucial in the formation of rain. As droplets are carried by the updrafts and downdrafts in a cloud, they collide and coalesce to form larger droplets. When the droplets become too large to be sustained on the air currents, they begin to fall as rain. Adding to this process, the cloud may be seeded with ice from higher altitudes, either via the cloud tops reaching , or via the cloud being seeded by ice from cirrus clouds. Contrast-enhanced ultrasound in medicine applies microscopic bubbles for imaging and therapy. Coalescence of ultrasound contrast agent microbubbles is studied to prevent embolies or to block tumour vessels ... [...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 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 gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
