Hawaii hotspot is a volcanic hotspot located near the Hawaiian Islands, in the northern Pacific Ocean. One of the most famous and well-studied places in the world, Hawaiian blobs are responsible for making the Hawaiian-Caesar mountain chain, a 5,800-kilometer (3,600 mile) volcano chain. These four volcanoes are active, two are inactive, and more than 123 are extinct, many of which have since land beneath the waves by erosion as seascapes and atolls. The chain extends from the southern island of Hawaii ? i to the edge of the Aleutian Trench, near the eastern edge of Russia.
While most volcanoes were created by geological activity on the plate boundary tectonics, Hawaiian hotspots are located far from plate boundaries. The classic hotspot theory, first proposed in 1963 by John Tuzo Wilson, proposed that one, the mantle coat still builds a volcano which, then disconnected from its source by the movement of the Pacific Plate, becomes increasingly inactive and eventually erodes beneath the surface of the sea over millions year. According to this theory, nearly 60 ° bends where the Emperor and Hawaiian segments of the chain meet are caused by a sudden shift in the movement of the Pacific Plate. In 2003, a new investigation into this irregularity led to the proposed theory of cellular hotspots, which indicated that the hotspot was cellular, not fixed, and that the 47-million-year bend was caused by a shift in hotspot motion rather than a plate.
The ancient Hawaiians were the first to know the increasing age and weather conditions of the northern volcanoes as they progressed in fishing expeditions along the islands. The volcanic situation of Hawaiian volcanoes and their constant battle with the sea is a major element in Hawaiian mythology, embodied in Pele, the god of the volcano. After the arrival of the Europeans on the island, in 1880-1881 James Dwight Dana directed the first formal geological study of volcanic hotspots, which confirmed the long-observed relationships of indigenous peoples. 1912 marks the establishment of Hawaii Volcano Observatory by volcanologist Thomas Jaggar, initiating a continuous scientific observation of the islands. In the 1970s, the mapping project began to gain more information about the geology of Hawaii's ocean floor complex.
Hotspots have been imaged tomographically, showing it to be 500 to 600 km (310 to 370 mi) and depths of up to 2,000 km (1,200 miles) deep, and studies based on olivine and garnet have shown that its magma space is about 1,500 ° C (2,730 Â ° F). In at least 85 million years of activity, the hotspot has produced approximately 750,000 km 3 (180,000 cuÃ, mi) rocks. The speed of the drifting chain slowly increases over time, causing the amount of time each active volcano drops, from 18 million years to 76 million-year-old Detroit Seamount, to just under 900,000 for one million- a year-old Kohala; on the other hand, the volume of eruptions has increased from 0.01 km 3 (0.002 cuÃ, mi) per year to about 0.21 km 3 (0.050Ã, cuÃ, mi ). Overall, this has led to a trend toward more active but rapidly-muted volcanoes, while volcanoes on the nearby side of the hotspot overlap (forming superstructures like the Hawaiian island span> i and ancient Maui Nui ), the oldest of the Emperor's seascapes spaced 200 km (120 miles) apart.
Video Hawaii hotspot
Theory
Tectonic plates generally focus on deformation and volcanism at plate boundaries. However, Hawaiian hotspots are over 3,200 kilometers (1,988Ã, mi) from the nearest plate boundary; while studying it in 1963, Canadian geophysicist J. Tuzo Wilson proposed a hotspot theory to explain these volcanic zones so far from ordinary conditions, a theory which has since been widely accepted.
Wilson stationary hotspot theory
Wilson proposes that mantle convection produces a small, hot upwelling beneath the surface of the Earth; this mantle of active heat mantle supplies magma which in turn sustains durable volcanic activity. This "mid-plate" volcanism builds a rising peak of a relatively unmarked seafloor, originally as a sea mountain and then as a fully fledged volcanic island. The local tectonic plates (in the case of Hawaiian hotspots, the Pacific Plate) slowly glide over the hotspots, carrying volcanoes without affecting the blobs. For hundreds of thousands of years, the supply of magma to the volcano was slowly cut off, eventually extinct. No longer active enough to defeat erosion, the volcano slowly sinks beneath the waves, becoming an underwater mountain once again. As the cycle progresses, the new volcanic center manifests, and the volcanic island reappears. The process continues until the coat prides itself on collapsing.
This cycle of growth and dormancy joins the volcano for millions of years, leaving behind traces of volcanic islands and seascapes on the ocean floor. According to Wilson's theory, Hawaii's volcanoes must be getting older and increasingly eroded the farther away from the hotspots, and this is easily observable; the oldest rock on the main Hawaiian islands, that of Kaua ? i, is about 5.5 million years old and deeply eroded, while rocks on the island of Hawaii ? i is a relative young age of 0.7 million years or less, with new lava constantly erupting in K? lauea, the center attended this hotspot. Another consequence of the theory is that the length and orientation of the chain serves to record the direction and speed of the Pacific Plate movement. The main feature of the Hawaiian trace is a sudden 60 Â ° bend in sections 40 to 50 million years old, and according to Wilson's theory, this is evidence of major changes in the direction of the plate, which would have initiated subduction along the western boundary of the Pacific Coast. Part of this theory has recently been challenged, and bends may be linked to the movement of the hotspot itself.
Geophysicists believe that hotspots originate from one of the two major distant frontiers on Earth, both superficial interfaces in the lower mantle between upper convection layers and lower non-convection layers, or more in D '' ("double-prime D" ) layer, about 200 kilometers (120 miles) thick and just above the core-mantle boundary. A mantle blob will start at the interface when the warmer bottom layer heats some of the cooler top layer. The heated, floating, and less viscous part of the upper layer becomes less dense due to thermal expansion, and rises to the surface as Rayleigh-Taylor instability. When the coat's fur reaches the bottom of the lithosphere, it heats it up and produces melt. The magma then goes to the surface, where it erupts as lava.
The argument for the validity of the hotspot theory generally centers on the steady development of the ages of the Hawaiian islands and features nearby: similar bend in the Macdonald hotspot trail, the south-west Austral-Marshall submarine chain; other Pacific hotspots follow a similar trend with the times from southeast to northwest in a relatively fixed position; and Hawaiian seismology studies that show an increase in temperature across the core-mantle border, which proves the mantle coat.
The shallow hotspot hypothesis
Another hypothesis is that melted anomalies are formed as a result of lithosphere extensions, allowing existing melts to rise to the surface. These smelting anomalies are usually called "hotspots", but under the underlying source hypothesis their underlying coat is not anomalously hot. In the case of the Hawaii-Hawaiian mountain chain, the Pacific plate boundary system is very different at ~ 80 Ma, when the Emperor's chain of volcanoes begins to form. There is evidence that the chain began on the spreading ridge (Pacific-Kula Ridge) which has now been sublimated in the Aleutian ditch. The focus of melting extract may have migrated from the ridge and into the inside of the plate, leaving behind a trail of volcanism behind it. This migration may occur because of the length of this plate to accommodate intraplate stress. Thus, long areas of melt melting can be maintained. Proponents of this hypothesis argue that the speed wave anomalies seen in seismic tomographic studies can not be reliably interpreted as hot upwelling derived from the lower mantle.
Moving the hotspot theory
The most challenging element of Wilson's theory is whether the hotspot is still related to the tectonic plate above it. Drill samples, collected by scientists as far back as 1963, suggest that hotspots may have drifted over time, at a relatively fast pace of about 4 centimeters (1.6 per year) during the late Cretaceous and Early Paleogens (81-47). Mya); in comparison, Mid-Atlantic Ridge spreads at a rate of 2.5 cm (1.0 inches) per year. In 1987, a study published by Peter Molnar and Joann Stock found that the hotspot did move relative to the Atlantic Ocean; However, they interpret this as a result of the relative movement of the North American and Pacific plates than it is from the hotspot itself.
In 2001, the Sea Drilling Program (since incorporated into the Integrated Ocean Drilling Program), an international research effort to study the world's seafloor, funded a two-month expedition aboard the research vessel NETWORK Resolution to collect lava samples from four volcanoes submerged in the Emperor. The project was drilled Detroit, Nintoku, and Koko sea mountains, all of which are located at the northwestern end of the chain, the oldest part. The lava samples were then tested in 2003, suggesting a Hawaiian mobile hotspot and shifting its movements as the cause of the bend. Lead scientist John Tarduno told National Geographic :
The Hawaiian bend is used as a classic example of how large plates can change movement quickly. You can find a diagram from Hawaii - Emperor bends go into almost every introductory geology book out there. It's really something that interests you. "
Despite major changes, changes in direction are never recorded by magnetic declination, fracture zone orientation or plate reconstruction; nor did continental collisions have occurred fast enough to produce real bends in chains. To test whether the bend was the result of a change in the direction of the Pacific Plate, the scientists analyzed lava sample geochemistry to determine where and when they formed. Age is determined by the radiometric dating of radioactive isotopes of potassium and argon. Researchers estimate that volcanoes formed during the period of 81 million to 45 million years ago. Tarduno and his team determined where volcanoes formed by analyzing rocks for magnetic mineral magnetite. While the hot lava from the volcanic eruption cools, the tiny granules inside the magnetite are parallel to the Earth's magnetic field, and lock in place once the rock is solidified. Researchers were able to verify the latitude in which volcanoes were formed by measuring the orientation of the grains in the magnetite. Paleomagnetis concludes that Hawaiian hotspots have drifted south sometime in its history, and that, 47 million years ago, the southern hotspot movement was slowing down, possibly even stopping completely.
Maps Hawaii hotspot
Learning history
Ancient Hawaii
It is likely that the Hawaiian archipelago became older when someone moved to the northwest allegedly by an ancient Hawaiian man long before the Europeans arrived. During their journey, the sailing Hawaiians see differences in erosion, soil formation, and vegetation, allowing them to conclude that the islands to the northwest (Ni ? ihau and Kaua ? i) older than the southeast (Maui and Hawaii). The idea is passed down from generation to generation through the legend of Pele, the fiery Hawaiian volcano goddess.
Pele was born from the spirit of the woman Haumea, or Hina, who, like all the gods and goddesses of Hawaii, descended from the supreme being, Papa, or Mother Earth, and Wakea, or Sky Father. According to myth, Pele originally lived in Kauai, when her sister, Nia, the Goddess of the Sea, attacked her for seducing her husband. Pele fled southeast to the island of Oahu. When forced by N'u to flee again, Pele moved southeast to Maui and finally to Hawaii, where he still lives in Halemaumau Crater at the top of K? Lauea. There he was safe, because the slopes of the volcano were so high that even the big waves of Namu could not reach him. Pele's mystical voyage, which alludes to the eternal struggle between the volcanic islands and the ocean waves, is consistent with the geological evidence about the age of the islands descending to the southeast.
Modern studies
Three of the earliest recorded volcano observers were Scottish scientist Archibald Menzies in 1794, James Macrae in 1825, and David Douglas in 1834. New reaching peaks proved daunting: Menzies took three attempts to ascend Mauna Loa, and Douglas died on the slopes of Mauna Kea. Exploring the United States Exploring Expeditions spent several months studying the islands in 1840-1841. The American geologist James Dwight Dana made the expedition, like Lieutenant Charles Wilkes, who spent most of the time leading a team of hundreds who hauled the pendulum to the top of Mauna Loa to measure gravity. Dana lives with missionary Titus Coan, who will provide decades of first-hand observation. Dana published a brief paper in 1852.
The Fund remained interested in the origins of the Hawaiian Islands, and directed a more in-depth study in 1880 and 1881. He asserted that the age of the islands increased with their distance from the most southeastern islands by observing the difference in their erosion rates. He also suggested that many other island chains in the Pacific show the same general improvement in ages from southeast to northwest. Dana concluded that the Hawaiian chain consists of two volcanic strands, located along different but parallel arches. He coined the terms "Loa" and "Kea" for two prominent trends. Kea trends include K volcano? Lauea, Mauna Kea, Kohala, Haleakal ?, and West Maui. Loan Trends include L? I ? hi, Mauna Loa, Hual? Lai, Kaho ? olawe, L? Na ? i, and West Moloka ? i. Dana proposes that Hawaiian Island alignment reflects local volcanic activity along major crack zones. The "big gap" theory of Fund functioned as a working hypothesis for further research until the mid-twentieth century.
The work of the Fund was followed by the geological expedition of C. E. Dutton in 1884, which refined and expanded the Fund's ideas. In particular, Dutton determined that the Hawaiian island actually harbored five volcanoes, while Dana counted three. This is because Dana initially considered K? Lauea as Mauna Loa wing ventilation, and Kohala as part of Mauna Kea. Dutton also perfected the observations of other Funds, and was credited with naming 'a'? and lava types-p-hoehoe, although the Fund has noted the difference. Stimulated by Dutton's expedition, Dana returned in 1887, and published many reports about his expedition in the American Journal of Science. In 1890 he published the most detailed manuscripts of his time, and remains the definitive guide to Hawaiian volcanism for decades. 1909 saw the publication of two large volumes extensively quoted from previous works that are now not in circulation.
In 1912 geologist Thomas Jaggar founded the Hawaii Volcano Observatory. The facility was taken over in 1919 by the National Oceanic and Atmospheric Administration and in 1924 by the United States Geological Survey (USGS), which marked the start of continuous volcanic observations on the island of Hawaii. The next century is a period of thorough investigation, characterized by contributions from many top scientists. The first complete evolution model was first formulated in 1946, by the USGS geologist and hydrologist Harold T. Stearns. Since then, progress has enabled studies of previously restricted observation areas (eg improved rock dating methods and underwater volcanic stages).
In the 1970s, the ocean floor of Hawaii was mapped using ship-based sonar. Computed SYNBAPS (Synthetic Bathymetric Profiling System) data fills holes between vessel-based bathimetric sonar measurements. From 1994 to 1998, the Japan Agency for Ocean-Earth Science and Technology (JAMSTEC) charted Hawaii in detail and studied the ocean floor, making it one of the most studied marine features in the world. The JAMSTEC project, a collaboration with USGS and other agencies, uses manned submersibles, remotely operated underwater vehicles, dredge samples, and core samples. Simarb EM300 multibeam sonar scanning system collects bathymetry and backscatter data.
Characteristics
Position
Hawaii hotspots have been imaged via seismic tomography, and are estimated to be 500-600 km (310-370Ã, mi) wide. The tomographic image shows a thin low-velocity zone extending to a depth of 1,500 km (930 mi), connecting with a large low-speed zone extending from a depth of 2,000 km (1,200 mi) to the core of the mantle. These low seismic velocity zones often show a warmer and more buoyant coat material, consistent with the feathers derived from the lower mantle and the fur pools in the upper mantle. The low velocity zone associated with the source of the clump is north of Hawaii ? i, indicates that the blob is tilted to a certain level, diverted southward by the flow of the mantle. Uranium decay-series disequilibria data have shown that the active area flowing from the melting zone is 220Ã, 40e, km (137Ã,  ± 25Ã, mi) Ã, km wide at the base and 280Ã,  ± Ã,  ± 40Ã, kmÃ,  ± (174Ã, ± 25 mi) on top upwelling mantle, consistent with tomographic measurements.
Temperature
Indirect studies have found that the magma chamber is located about 90-100 kilometers (56-62Ã, mi) underground, which corresponds to the estimated depth of limestone rocks in oceanic lithosphere; this may indicate that the lithosphere acts as a cover on the fusion by holding up the magma climb. The original temperature of magma is found in two ways, by testing the melting point of garnet in lava and by adjusting the lava for olivine deterioration. Both USGS tests seem to confirm a temperature of about 1,500 ° C (2,730 ° F); if compared, the approximate temperature for the mid-ocean basalt ridge is about 1.325 ° C (2.417 ° F).
The surface heat flow anomalies around the Hawaiian Swell are only from the order of 10 mW/m 2 , far less than the continental United States range of 25 to 150 mW/m 2 . This is not unexpected for the classic model of hot and buoyant blobs in the mantle. However, it has been shown that other clumps show varying surface heat fluctuations and this variability may be due to variable hydrothermal flow in the Earth's crust above the hotspot. This fluid flow effectively removes heat from the crust, and the measured conduction heat current is lower than the total actual surface heat flux. The low heat across the Swell Hawaiian shows that it is not supported by floating crust or upper lithosphere, but is somewhat propped up by a blob of hot (and therefore less dense) mantle that causes the surface to rise through a mechanism known as "dynamic topography".
Movement
Hawaii volcano drifted northwest from a hotspot at about 5-10 centimeters (2.0-3.9 inches per year). Hotspots have migrated southward about 800 kilometers (497 mi) relative to the Emperor's chain. The paleomagnetic study supports this conclusion based on changes in the Earth's magnetic field, images embedded in rocks during their freezing, indicating that these sea-mountains form at higher latitudes than today's Hawaii. Before the bend, the hotspot migrates about 7 centimeters (2.8 inches) per year; the rate of movement changes at the time of the bend to about 9 cm (3.5 inches) per year. The Sea Drilling Program provides the most up-to-date knowledge of the irregularities. The 2001 expedition drilled six seascapes and tested samples to determine their original latitudes, and thus the characteristics and speed of the total pattern of hotspot shifts.
Each successive volcano spends less active time attached to the plume. The big difference between the youngest and the oldest lava between the Emperor and the Hawaiian volcano shows that the speed of the hotspot is increasing. For example, Kohala, the oldest volcano on the island of Hawaii, was one million years old and last erupted 120,000 years ago, a period under 900,000 years old; while one of the oldest, Detroit Seamount, experienced 18 million years or more of volcanic activity.
The oldest volcano in the chain, Meiji Seamount, perched on the edge of the Aleutian Trench, was formed 85 million years ago. At current speeds, undersea volcanoes will be destroyed within a few million years, as the Pacific Plate shifts beneath the Eurasian Plate. It is unknown whether submarine mountain chains have undergone subduction under the Eurasian Plate, and whether the hotspots are older than Meiji Seamount, since older seafloor has been destroyed by plate margins. It is also possible that a collision near the Aleutian Trellis has altered the speed of the Pacific Plate, explaining the hotspot chain's bend; the relationship between these features is still under investigation.
Magma
The composition of volcanic magma has changed significantly according to the analysis of the strontium-niobium-palladium element ratio. Emperor Seamounts is active for at least 46 million years, with the oldest lava dated Cretaceous Period, followed by 39 million years of other activity along the Hawaiian chain segment, for a total of 85 million years. The data show vertical variability in the amount of strontium present both in the alkaline stage (early stage) and tholeitic (later stages) of lava. The systematic improvement slows drastically at the turn.
Almost all magma created by hotspots is frozen basalt; volcanoes are constructed almost entirely of these or similar in composition but gabbro and diabras are more rough. Other igneous rocks such as nefelinite are present in small amounts; this is often the case in older volcanoes, the most famous, the Detroit Seamount. Most explosions are watery because basaltic magma is less viscous than magma which is characteristic of a more explosive eruption such as andesitic magma that produces a spectacular and dangerous eruption around the Pacific Rim margin. Volcanoes fall into several categories of eruptions. Hawaii volcanoes are called "Hawaiian-type". Lahar Hawaii spills from the crater and forms a long stream of dense lush rocks, flowing down the slopes, covering the vast land and replacing the ocean with new land.
The frequency of eruptions and scale
There is significant evidence that the lava flow rate has increased. For the last six million years they were much higher than before, above 0.095 km 3 (0.023Ã, Â ± cuÃ, mi) per year. The average for the last million years is even higher, about 0.21 km 3 (0.050Ã, cuÃ, mi). For comparison, the average production rate on the ridge at sea is about 0.02 km 3 (0.0048Ã, Â ° c) for every 1,000 kilometers (621Ã, mi) of the ridge. The level along the Emeror seamount chain averages about 0.01 cubic kilometers (0.0024 cu mi) per year. That number is almost zero for the first five million years or so in a hotspot's life. Average lava production rates along the Hawaiian chain have been greater, at 0.017 km 3 (0.0041Ã, cuÃ, mi) per year. In total, the hotspot has produced approximately 750,000 cubic kilometers (180,000 cuÃ, mi) of lava, enough to cover California with a layer of about 1.5 kilometers (1 mi) thick.
The distance between individual volcanoes has shrunk. Although the volcano has drifted north faster and spent less active time, the volumes of modern eruptions far greater than hotspots have resulted in closer volcanoes, and many of them overlap, forming superstructures like Hawaiian ? i island and ancient Maui Nui. Meanwhile, many volcanoes in the Emperor's mountains are separated by 100 kilometers (62 mi) or even as far as 200 kilometers (124 mi).
Topography and geoid
A detailed topographic analysis of the Hawaiian-kaisar mountain chain reveals a hotspot as a high topographic center, and the height falls with distance from the hotspot. The fastest elevation elevation and the highest ratio between topography and geoid height are in the south-east of the chain, falling with distance from hotspots, especially at the crossing of the fractured zone of Molokai and Murray. The most likely explanation is that the area between the two zones is more susceptible to reheating than most chains. Another possible explanation is that the power of the hotspot swells and subsides over time.
In 1953, Robert S. Dietz and his colleagues first identified swollen behavior. It is recommended that the cause is an upwelling coat. The work then refers to tectonic lift, caused by reheating in the lower lithosphere. However, normal seismic activity beneath the waves, as well as the lack of detectable heat flow, led scientists to suggest dynamic topography as the cause, in which the blobs of hot and buoyant motions support high surface topography around the island. Understanding the waves of Hawaii has important implications for the study of hotspots, the formation of the island, and the inner Earth.
Seismicity
Hawaii hotspot is a very active seismic zone with thousands of earthquakes that occur on and near the island of Hawaii each year. Most are too small to be felt by people but some are large enough to cause minor to moderate damage. The most destructive earthquake record is the 2 April earthquake of 1868 which has magnitude 7.9 on the Richter scale. This triggered a landslide in Mauna Loa, 5Ã, mi (8.0 km) north of Pahala, killing 31 people. Tsunami swallowed another 46 souls. The villages of Punalu'u, Nole, Kawaa, Honuapo, and Keauhou Landing were severely damaged. The tsunami reportedly rolled over the top of the coconut tree to 60Ã, ft (18 m) high and reached the interior of a quarter mile (400 meters) distance in some places.
Volcano
Over 85 million years of history, Hawaiian hotspots have created at least 129 volcanoes, more than 123 of which are extinct volcanoes, underwater volcanoes and atolls, four of which are active volcanoes, and two of them are volcanoes not active. They can be organized into three general categories: the Hawaiian archipelago, comprising most of the US Hawaii state and is the site of all modern volcanic activity; The Northwest Hawaii Islands, which consists of coral atolls, extinct islands, and atoll islands; and Emperor Seamounts, all of which have eroded and subsided into the sea and become underwater mountains and guyots (flat flat mountains).
Volcanic Characteristics
Hawaiian volcanoes are characterized by frequent crack eruptions, large size (thousands of cubic kilometers in volume), and rough and decentralized shapes. Rift zones are a prominent feature in this volcano, and explain their seemingly random volcanic structure. The highest mountain in the Hawaiian chain, Mauna Kea, rises 4,205 meters (13,796 feet) above sea level on average. Measured from its base on the sea floor, it is the highest mountain in the world, at 10,203 meters (33,474 ft); Mount Everest rises 8,848 meters (29,029 feet) above sea level. Hawaii is surrounded by numerous sea mountains; However, they are found not connected to hotspots and vulcanism. K? Lauea has been erupting continuously since 1983 through Pu? U ????, a small volcano cone, which has become an attraction for volcanologists and tourists alike.
Landslide
The Hawaiian Islands are filled with a large number of landslides sourced from the collapse of volcanic. The bathymetry mapping has revealed at least 70 large landslides on the side of the island as long as 20 km (12 mi) in length, and the longest is 200 km (120 miles) long and more than 5,000 km 3 (1,200 cuÃ, mi) in volume. The flow of debris can be divided into two broad categories: degeneration, mass movement over slopes that slowly flatten their originators, and more avalanches of disaster debris, breaking down the slopes of the volcano and scattering volcanic debris over the slopes they. This slide has caused major tsunamis and earthquakes, cracked volcanic massive, and debris scattered hundreds of miles away from their source.
Deterioration tends to be deeply rooted in its originators, moving stones up to 10 km (6 miles) deep inside a volcano. Forced ahead by the mass of newly-released volcanic material, the slump can creep forward slowly, or soar ahead in the spacings that have caused the largest earthquake in Hawaii, in 1868 and 1975. The landslide ruins, meanwhile, are thinner and longer, and defined by the volcanic amphitheater in their head and the windy terrain at their base. A fast-moving avalanche carries 10 km (6 mi) blocks of tens of kilometers away, disturbing the local water column and causing a tsunami. Evidence of this event exists in the form of high ocean sediments on the slopes of Hawaii volcano, and has damaged the slopes of several Emperor volcanoes, such as Daikakuji Guyot and Detroit Seamount.
Evolution and construction
Hawaii volcanoes follow the established cycle of growth and erosion. Once a new volcano is formed, its lava output gradually increases. Their height and activity both reached a peak when the volcano was about 500,000 years old and then quickly declined. Eventually he becomes inactive, and eventually extinct. Erosion then liberate the volcano until it becomes an underwater mountain.
This life cycle consists of several stages. The first stage is the stage of the submarine preshield, currently represented only by L ?? ihi Seamount. During this stage, volcanoes build height through an increasingly frequent eruption. Sea pressure prevents explosive eruptions. Cold water quickly freezes the lava, producing a pillow lava that is typical of volcanic activity under the sea.
When the lower mountain slowly grows, it passes through the shield stage. It forms many adult features, such as the caldera, while submerged. Peaks eventually penetrate the surface, and "battle" lava and sea water for control when the volcano enters an explosive subfase. This development stage is exemplified by explosive vapor ventilation. This stage produces most of the volcanic ash, due to waves that dampen lava. Conflict between lahars and the ocean affects the mythology of Hawaii.
The volcano enters subaerial subfase after it is high enough to get out of the water. Now the volcano puts on 95% of its water level above it for about 500,000 years. After that the eruption becomes less explosive. Lava released at this stage often includes p hoehoe and Ê »a, and the currently active Hawaiian volcano Mauna Loa and K? Lauea, is in this phase. Hawaiian lava is often watery, yellow, slow, and relatively predictable; USGS tracks the places most likely to run, and maintains the tourist sites to see lava.
After the subaerial phase the volcano enters a series of post-launch stages involving decline and erosion, becoming an atoll and eventually an underwater mountain. Once the Pacific Plate moves it from the tropics 20Ã, Â ° C (68Ã, Â ° F), the coral is mostly dead, and the extinct volcano becomes one of the 10,000 seabeds stranded across the globe. Every Emperor's mountain is a dead volcano.
See also
- List of volcanic hotspots
- List of volcanoes in the Pacific Ocean
- List of volcanoes in the United States
- Maui Nui
- Type of volcanic eruption
References
External links
- Pele-Goddess of Fire - Details of Pele's complete story, according to Hawaiian myth.
- The long trail of Hawaiian hotspots - USGS articles on the Hawaiian island chain.
- The Evolution of Hawaii Volcano - USGS article on the evolution of Hawaiian volcanoes from time to time.
- Short film Inside Hawaiian Volcanoes (1989) is available for free download on the Internet Archive
Source of the article : Wikipedia
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