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99-724: The chain can be divided into three subsections. The first, the Hawaiian archipelago (also known as the Windward isles ), consists of the islands comprising the U.S. state of Hawaii . As it is the closest to the hotspot, this volcanically active region is the youngest part of the chain, with ages ranging from 400,000 years to 5.1 million years. The island of Hawaiʻi is composed of five volcanoes, of which four ( Kilauea , Mauna Loa , Hualalai , and Mauna Kea ) are active. The island of Maui has one active volcano, Haleakalā . Kamaʻehuakanaloa Seamount continues to grow offshore of Hawaiʻi island, and

198-545: A subduction zone at the border of Russia . The oldest confirmed age for one of the Emperor Seamounts is 81 million years, for Detroit Seamount . However, Meiji Seamount , located to the north of Detroit Seamount, is likely somewhat older. In 1963, geologist John Tuzo Wilson hypothesized the origins of the Hawaiian–Emperor seamount chain, explaining that they were created by a hotspot of volcanic activity that

297-482: A continuous supply of magma to a hotspot. As the overlying tectonic plate moves over this hotspot, the eruption of magma from the fixed plume onto the surface is expected to form a chain of volcanoes that parallels plate motion. The Hawaiian Islands chain in the Pacific Ocean is the archetypal example. It has recently been discovered that the volcanic locus of this chain has not been fixed over time, and it thus joined

396-414: A core mantle heat flux of 20 mW/m , while the cycle time (the time between plume formation events) is about 2000 million years. The number of mantle plumes is predicted to be about 17. When a plume head encounters the base of the lithosphere, it is expected to flatten out against this barrier and to undergo widespread decompression melting to form large volumes of basalt magma. It may then erupt onto

495-536: A high Sr/ Sr ratio. Helium in OIB shows a wider variation in the He/ He ratio than MORB, with some values approaching the primordial value. The composition of ocean island basalts is attributed to the presence of distinct mantle chemical reservoirs formed by subduction of oceanic crust. These include reservoirs corresponding to HUIMU, EM1, and EM2. These reservoirs are thought to have different major element compositions, based on

594-405: A long thin conduit connecting the top of the plume to its base, and a bulbous head that expands in size as the plume rises. The entire structure resembles a mushroom. The bulbous head of thermal plumes forms because hot material moves upward through the conduit faster than the plume itself rises through its surroundings. In the late 1980s and early 1990s, experiments with thermal models showed that as

693-612: A lower temperature. Mantle material containing a trace of partial melt (e.g., as a result of it having a lower melting point), or being richer in Fe, also has a lower seismic wave speed and those effects are stronger than temperature. Thus, although unusually low wave speeds have been taken to indicate anomalously hot mantle beneath hotspots, this interpretation is ambiguous. The most commonly cited seismic wave-speed images that are used to look for variations in regions where plumes have been proposed come from seismic tomography. This method involves using

792-527: A mantle plume postulated to have caused the breakup of Eurasia and the opening of the North Atlantic, now suggested to underlie Iceland . Current research has shown that the time-history of the uplift is probably much shorter than predicted, however. It is thus not clear how strongly this observation supports the mantle plume hypothesis. Basalts found at oceanic islands are geochemically distinct from mid-ocean ridge basalt (MORB). Ocean island basalt (OIB)

891-643: A network of seismometers to construct three-dimensional images of the variation in seismic wave speed throughout the mantle. Seismic waves generated by large earthquakes enable structure below the Earth's surface to be determined along the ray path. Seismic waves that have traveled a thousand or more kilometers (also called teleseismic waves ) can be used to image large regions of Earth's mantle. They also have limited resolution, however, and only structures at least several hundred kilometers in diameter can be detected. Seismic tomography images have been cited as evidence for

990-553: A number of mantle plumes in Earth's mantle. There is, however, vigorous on-going discussion regarding whether the structures imaged are reliably resolved, and whether they correspond to columns of hot, rising rock. The mantle plume hypothesis predicts that domal topographic uplifts will develop when plume heads impinge on the base of the lithosphere. An uplift of this kind occurred when the North Atlantic Ocean opened about 54 million years ago. Some scientists have linked this to

1089-399: A plume developed into a weakly defined hypothesis, which as a general term is currently neither provable nor refutable. The dissatisfaction with the state of the evidence for mantle plumes and the proliferation of ad hoc hypotheses drove a number of geologists, led by Don L. Anderson , Gillian Foulger , and Warren B. Hamilton , to propose a broad alternative based on shallow processes in

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1188-503: A separate causal category of terrestrial volcanism with implications for the study of hotspots and plate tectonics. In 1997 it became possible using seismic tomography to image submerging tectonic slabs penetrating from the surface all the way to the core-mantle boundary. For the Hawaii hotspot , long-period seismic body wave diffraction tomography provided evidence that a mantle plume is responsible, as had been proposed as early as 1971. For

1287-628: A settlement as early as 124 AD. Captain James Cook , RN , visited the islands on January 18, 1778, and named them the "Sandwich Islands" in honor of The 4th Earl of Sandwich , who as the First Lord of the Admiralty was one of his sponsors. This name was in use until the 1840s, when the local name "Hawaii" gradually began to take precedence. The Hawaiian Islands have a total land area of 6,423.4 square miles (16,636.5 km ). Except for Midway, which

1386-572: A significant role in northern directional pull on the Pacific Plate. Around 47 million years ago, these northern forces came to an end. Near the same time, there were notable changes in the movement of the Hawaiian hotspot. Approximately 50 Ma, the Hawaiian hotspot started to drift to the south. However, there is not a widely accepted theory as to the mechanism that caused the hotspot to drift. The combination of these events along with new subduction zones in

1485-700: A single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America. Flood basalts in the oceans are known as oceanic plateaus, and include the Ontong Java plateau of the western Pacific Ocean and the Kerguelen Plateau of the Indian Ocean. The narrow vertical conduit, postulated to connect the plume head to the core-mantle boundary, is viewed as providing

1584-578: A tectonic plate can shift direction comparatively suddenly. A look at the USGS map on the origin of the Hawaiian Islands clearly shows this "spearpoint". In a more recent study, Sharp and Clague interpret the bend as starting at about 50 million years ago. They also conclude that the bend formed from a "traditional" cause—a change in the direction of motion of the Pacific plate. However, recent research shows that

1683-462: Is a strong thermal (temperature) discontinuity. The temperature of the core is approximately 1,000 degrees Celsius higher than that of the overlying mantle. Plumes are postulated to rise as the base of the mantle becomes hotter and more buoyant. Plumes are postulated to rise through the mantle and begin to partially melt on reaching shallow depths in the asthenosphere by decompression melting . This would create large volumes of magma. This melt rises to

1782-482: Is an unincorporated territory of the United States, these islands and islets are administered as Hawaii —the 50th state of the United States. The eight major islands of Hawaii (Windward Islands) are listed above. All except Kaho'olawe are inhabited. The state of Hawaii counts 137 "islands" in the Hawaiian chain. This number includes all minor islands (small islands), islets (even smaller islands) offshore of

1881-454: Is consistent with a system that tends toward equilibrium: as matter rises in a mantle plume, other material is drawn down into the mantle, causing rifting. In parallel with the mantle plume model, two alternative explanations for the observed phenomena have been considered: the plate hypothesis and the impact hypothesis. Since the beginning of the 21st century, a paradigm debate "The great plume debate" has developed around plumes, in which

1980-536: Is enriched in trace incompatible elements , with the light rare earth elements showing particular enrichment compared with heavier rare earth elements. Stable isotope ratios of the elements strontium , neodymium , hafnium , lead , and osmium show wide variations relative to MORB, which is attributed to the mixing of at least three mantle components: HIMU with a high proportion of radiogenic lead, produced by decay of uranium and other heavy radioactive elements; EM1 with less enrichment of radiogenic lead; and EM2 with

2079-481: Is more diverse compositionally than MORB, and the great majority of ocean islands are composed of alkali basalt enriched in sodium and potassium relative to MORB. Larger islands, such as Hawaii or Iceland, are mostly tholeiitic basalt, with alkali basalt limited to late stages of their development, but this tholeiitic basalt is chemically distinct from the tholeiitic basalt of mid-ocean ridges. OIB tends to be more enriched in magnesium, and both alkali and tholeiitic OIB

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2178-438: Is posited to exist where super-heated material forms ( nucleates ) at the core-mantle boundary and rises through the Earth's mantle. Rather than a continuous stream, plumes should be viewed as a series of hot bubbles of material. Reaching the brittle upper Earth's crust they form diapirs . These diapirs are "hotspots" in the crust. In particular, the concept that mantle plumes are fixed relative to one another and anchored at

2277-522: Is relatively fluid compared with magmas typically involved in more explosive eruptions, such as the andesitic magmas that produce some of the spectacular and dangerous eruptions around the margins of the Pacific basin. Hawaiʻi island (the Big Island) is the biggest and youngest island in the chain, built from five volcanoes. Mauna Loa , taking up over half of the Big Island, is the largest shield volcano on

2376-457: Is situated entirely on an archipelago, and the only state not geographically connected with North America . The Northwestern islands (sometimes called the Leeward Islands) and surrounding seas are protected as a National Monument and World Heritage Site . The date of the first settlements of the Hawaiian Islands is a topic of continuing debate. Archaeological evidence seems to indicate

2475-482: Is that material and energy from Earth's interior are exchanged with the surface crust in two distinct and largely independent convective flows: The plume hypothesis was simulated by laboratory experiments in small fluid-filled tanks in the early 1970s. Thermal or compositional fluid-dynamical plumes produced in that way were presented as models for the much larger postulated mantle plumes. Based on these experiments, mantle plumes are now postulated to comprise two parts:

2574-557: Is the only known volcano in the chain in the submarine pre-shield stage . The second part of the chain is composed of the Northwestern Hawaiian Islands , collectively referred to as the Leeward isles , the constituents of which are between 7.2 and 27.7 million years old. Erosion has long since overtaken volcanic activity at these islands, and most of them are atolls, atoll islands, and extinct islands. They contain many of

2673-703: The Chagos-Laccadive Ridge , the Louisville Ridge , the Ninety East Ridge and Kerguelen , Tristan , and Yellowstone . While there is evidence that the chains listed above are time-progressive, it has been shown that they are not fixed relative to one another. The most remarkable example of this is the Emperor chain, the older part of the Hawaii system, which was formed by migration of the hotspot in addition to

2772-519: The Earth's mantle . The islands are about 1,860 miles (3,000 km) from the nearest continent and are part of the Polynesia subregion of Oceania . The U.S. state of Hawaii occupies the archipelago almost in its entirety (including the mostly uninhabited Northwestern Hawaiian Islands ), with the sole exception of Midway Atoll (a United States Minor Outlying Island ). Hawaii is the only U.S. state that

2871-517: The Hawaiian Volcano Observatory run by the USGS . Hawaii accounted for 7.3% of the United States' reported earthquakes with a magnitude 3.5 or greater from 1974 to 2003, with a total 1533 earthquakes. Hawaii ranked as the state with the third most earthquakes over this time period, after Alaska and California . On October 15, 2006, there was an earthquake with a magnitude of 6.7 off

2970-564: The Sandwich Islands by Europeans (not by Kānaka Maoli , the people native to the islands), the present name for the archipelago is derived from the name of its largest island, Hawaiʻi. The archipelago sits on the Pacific plate . The islands are exposed peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain , formed by volcanic activity over a hotspot in

3069-578: The Society Islands around 1025 to 1120 C.E., and in the Marquesas Islands sometime between 1100 and 1200 C.E. Polynesians arrived sometime between 940 and 1200 AD. Kamehameha I , the ruler of the island of Hawaii, conquered and unified the islands for the first time, establishing the Kingdom of Hawaii in 1795. The kingdom became prosperous and important for its agriculture and strategic location in

Hawaiian–Emperor seamount chain - Misplaced Pages Continue

3168-608: The Sudbury Igneous Complex in Canada are known to have caused melting and volcanism. In the impact hypothesis, it is proposed that some regions of hotspot volcanism can be triggered by certain large-body oceanic impacts which are able to penetrate the thinner oceanic lithosphere , and flood basalt volcanism can be triggered by converging seismic energy focused at the antipodal point opposite major impact sites. Impact-induced volcanism has not been adequately studied and comprises

3267-531: The Yellowstone hotspot , seismological evidence began to converge from 2011 in support of the plume model, as concluded by James et al., "we favor a lower mantle plume as the origin for the Yellowstone hotspot." Data acquired through Earthscope , a program collecting high-resolution seismic data throughout the contiguous United States has accelerated acceptance of a plume underlying Yellowstone. Although there

3366-490: The list of extinct animals of the Hawaiian Islands . As of 2009 , many of the remaining endemic species are considered endangered . On June 15, 2006, President George W. Bush issued a public proclamation creating Papahānaumokuākea Marine National Monument under the Antiquities Act of 1906. The Monument encompasses the northwestern Hawaiian Islands and surrounding waters, forming the largest marine wildlife reserve in

3465-404: The lower mantle under Africa and under the central Pacific. It is postulated that plumes rise from their surface or their edges. Their low seismic velocities were thought to suggest that they are relatively hot, although it has recently been shown that their low wave velocities are due to high density caused by chemical heterogeneity. Some common and basic lines of evidence cited in support of

3564-510: The trade winds on their north and east flanks (the windward side) as a result of orographic precipitation . Coastal areas in general and especially the south and west flanks, or leeward sides, tend to be drier. In general, the lowlands of Hawaiian Islands receive most of their precipitation during the winter months (October to April). Drier conditions generally prevail from May to September. The tropical storms , and occasional hurricanes , tend to occur from July through November. During

3663-576: The 1820s based on a census conducted by American missionaries, 82,203 in the 1850 Hawaiian Kingdom census, 40,622 in the final Hawaiian Kingdom census of 1890, 39,504 in the sole census by the Republic of Hawaii in 1896, and 37,656 in the first census conducted by the United States in 1900. Thereafter the Native Hawaiian population in Hawaii increased with every census, reaching 680,442 in 2020 (including people of mixed heritage). In 1893 Queen Liliʻuokalani

3762-489: The Big Island. The volcanoes on the remaining islands are extinct as they are no longer over the Hawaii hotspot. The Kamaʻehuakanaloa Seamount is an active submarine volcano that is expected to become the newest Hawaiian island when it rises above the ocean's surface in 10,000–100,000 years. Hazards from these volcanoes include lava flows that can destroy and bury the surrounding surface, volcanic gas emissions, earthquakes and tsunamis listed above, submarine eruptions affecting

3861-476: The Earth's core, in basalts at oceanic islands. However, so far conclusive proof for this is lacking. The plume hypothesis has been tested by looking for the geophysical anomalies predicted to be associated with them. These include thermal, seismic, and elevation anomalies. Thermal anomalies are inherent in the term "hotspot". They can be measured in numerous different ways, including surface heat flow, petrology, and seismology. Thermal anomalies produce anomalies in

3960-573: The Earth. The measurement from sea level to summit is more than 2.5 miles (4 km), from sea level to sea floor about 3.1 miles (5 km). The Hawaiian Islands have many earthquakes , generally triggered by and related to volcanic activity. Seismic activity, as a result, is currently highest in the southern part of the chain. Both historical and modern earthquake databases have correlated higher magnitude earthquakes with flanks of active volcanoes, such as Mauna Loa and Kilauea. The combination of erosional forces, which cause slumping and landslides, with

4059-419: The Hawaiian Islands. Explosive volcanic activity can cause tsunamis. The island of Molokaʻi had a catastrophic collapse or debris avalanche over a million years ago; this underwater landslide likely caused tsunamis. The Hilina Slump on the island of Hawaiʻi is another potential place for a large landslide and resulting tsunami. The city of Hilo on the Big Island has been most affected by tsunamis, where

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4158-625: The Pacific. Kamehameha was aided by European military technology that became available once an expedition led by British explorer James Cook reached the islands in 1778, the first sustained contact with Europeans. American immigration, led by Protestant missionaries , and Native Hawaiian emigration, mostly on whaling ships but also in high numbers as indentured servants and as forced labour, began almost immediately after Cook's arrival. Americans established plantations to grow crops for export. Their farming methods required substantial labor. Waves of permanent immigrants came from Japan , China , and

4257-606: The Philippines to work in the cane and pineapple fields. The government of Japan organized and gave special protection to its people, who comprised about 25 percent of the Hawaiian population by 1896. The Hawaiian monarchy encouraged this multi-ethnic society, initially establishing a constitutional monarchy in 1840 that promised equal voting rights regardless of race, gender, or wealth. The population of Native Hawaiians declined precipitously from an unknown number prior to 1778 (estimated to be around 300,000). It fell to around 142,000 in

4356-414: The absence of such predators. The growing population of humans, especially through European and American colonisation and development, has also led to deforestation , forest degradation , treeless grasslands, and environmental degradation . As a result, many species which depended on forest habitats and food became extinct—with many current species facing extinction. As humans cleared land for farming with

4455-494: The area. Informational notes Citations Further reading Hawaiian Islands The Hawaiian Islands ( Hawaiian : Mokupuni Hawaiʻi ) are an archipelago of eight major volcanic islands , several atolls , and numerous smaller islets in the North Pacific Ocean , extending some 1,500 miles (2,400 kilometers) from the island of Hawaiʻi in the south to northernmost Kure Atoll . Formerly called

4554-417: The bend in the Emperor chain to date. In addition to previous interpretations of the cause of the bend in the seamount chain, Hu et al. have proposed a close relationship between mantle plume migration and change in plate tectonic motion. Expanding on previous models, it has been interpreted that the Pacific Plate's motion was predominantly in the northern direction prior to 47 million years ago. Traditionally,

4653-407: The bend to be attributed completely to hotspot motion, the pacific plate would have to remain stationary from 81 Ma to 43 Ma. Thus, is not true as magnetic anomalies on the pacific plate indicate motion of around 60 mm per year during that period. This model consisting of a change in plate motion combined with small north-south motions of the hotspot seems to be the best supported theory concerning

4752-426: The bend was caused only by a change in the Pacific plate motion. Second, that the bend was caused by hotspot movement only. In 2004 geologist Yaoling Niu proposed a model that attributed the bend largely to a change in plate motion along with some motion in the hotspot. Niu proposes that the bend starts at 43 Ma which is caused by a "trench jam". This "trench jam" is caused by the arrival of the Emperor chain seamounts at

4851-507: The bottom of the mantle transition zone at 650 km depth. Subduction to greater depths is less certain, but there is evidence that they may sink to mid-lower-mantle depths at about 1,500  km depth. The source of mantle plumes is postulated to be the core-mantle boundary at 3,000  km depth. Because there is little material transport across the core-mantle boundary, heat transfer must occur by conduction, with adiabatic gradients above and below this boundary. The core-mantle boundary

4950-428: The bulbous head expands it may entrain some of the adjacent mantle into itself. The size and occurrence of mushroom mantle plumes can be predicted by the transient instability theory of Tan and Thorpe. The theory predicts mushroom-shaped mantle plumes with heads of about 2000 km diameter that have a critical time (time from onset of heating of the lower mantle to formation of a plume) of about 830 million years for

5049-589: The club of the many type examples that do not exhibit the key characteristic originally proposed. The eruption of continental flood basalts is often associated with continental rifting and breakup. This has led to the hypothesis that mantle plumes contribute to continental rifting and the formation of ocean basins. The chemical and isotopic composition of basalts found at hotspots differs subtly from mid-ocean-ridge basalts. These basalts, also called ocean island basalts (OIBs), are analysed in their radiogenic and stable isotope compositions. In radiogenic isotope systems

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5148-429: The core-mantle boundary (2900 km depth) to a possible layer of shearing and bending at 1000 km. They were detectable because they were 600–800 km wide, more than three times the width expected from contemporary models. Many of these plumes are in the large low-shear-velocity provinces under Africa and the Pacific, while some other hotspots such as Yellowstone were less clearly related to mantle features in

5247-408: The core-mantle boundary would provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hotspots, for example, the Hawaiian–Emperor seamount chain . However, paleomagnetic data show that mantle plumes can also be associated with Large Low Shear Velocity Provinces (LLSVPs) and do move relative to each other. The current mantle plume theory

5346-463: The core-mantle boundary. Lithospheric extension is attributed to processes related to plate tectonics. These processes are well understood at mid-ocean ridges, where most of Earth's volcanism occurs. It is less commonly recognised that the plates themselves deform internally, and can permit volcanism in those regions where the deformation is extensional. Well-known examples are the Basin and Range Province in

5445-438: The correlation between major element compositions of OIB and their stable isotope ratios. Tholeiitic OIB is interpreted as a product of a higher degree of partial melting in particularly hot plumes, while alkali OIB is interpreted as a product of a lower degree of partial melting in smaller, cooler plumes. In 2015, based on data from 273 large earthquakes, researchers compiled a model based on full waveform tomography , requiring

5544-518: The equivalent of 3 million hours of supercomputer time. Due to computational limitations, high-frequency data still could not be used, and seismic data remained unavailable from much of the seafloor. Nonetheless, vertical plumes, 400 C hotter than the surrounding rock, were visualized under many hotspots, including the Pitcairn , Macdonald , Samoa , Tahiti , Marquesas , Galapagos , Cape Verde , and Canary hotspots. They extended nearly vertically from

5643-664: The especially unpredictable nature of the forces that trigger earthquakes, and partially because these events occur at relatively shallow depths. Flank earthquakes typically occur at depths ranging from 5 to 20 km, increasing the hazard to local infrastructure and communities. Earthquakes and landslides on the island chain have also been known to cause tsunamis . Most of the early earthquake monitoring took place in Hilo , by missionaries Titus Coan and Sarah J. Lyman and her family. Between 1833 and 1896, approximately 4 or 5 earthquakes were reported per year. Today, earthquakes are monitored by

5742-552: The force pulling the Pacific Plate to the north was attributed to the Izanagi - Pacific Ridge subduction zone. However, in a 2021 study, Hu et al. proposed that this subduction zone was not a strong enough force to have been pulling the Pacific Plate on its own. Instead, they introduced the concept that there was an intra-oceanic subduction zone involving the Kronotsky and Olyutorsky arcs. According to their findings, this subduction zone played

5841-414: The hotspot itself may have moved with time. Some evidence comes from analysis of the orientation of the ancient magnetic field preserved by magnetite in ancient lava flows sampled at four seamounts: this evidence from paleomagnetism shows a more complex history than the commonly accepted view of a stationary hotspot. If the hotspot had remained above a fixed mantle plume during the past 80 million years,

5940-468: The importation of industrialized farming practices through European and American encroachment, monocultural crop production replaced multi-species systems . The arrival of the Europeans had a more significant impact, with the promotion of large-scale single-species export agriculture and livestock grazing. This led to increased clearing of forests, and the development of towns, adding many more species to

6039-453: The in-rushing water is accentuated by the shape of Hilo Bay . Coastal cities have tsunami warning sirens. A tsunami resulting from an earthquake in Chile hit the islands on February 27, 2010. It was relatively minor, but local emergency management officials utilized the latest technology and ordered evacuations in preparation for a possible major event. The Governor declared it a "good drill" for

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6138-473: The largest such protected areas in the world. The proclamation limits tourism to the area, and called for a phase-out of fishing by 2011. The oldest and most heavily eroded part of the chain are the Emperor seamounts, which are 39 to 85 million years old. The Emperor and Hawaiian chains form an angle of about 120°. This bend was long attributed to a relatively sudden change of 60° in the direction of plate motion, but research conducted in 2003 suggests that it

6237-419: The latitude as recorded by the orientation of the ancient magnetic field preserved by magnetite (paleolatitude) should be constant for each sample; this should also signify original cooling at the same latitude as the current location of the Hawaiian hotspot. Instead of remaining constant, the paleolatitudes of the Emperor Seamounts show a change from north to south, with decreasing age. The paleomagnetic data from

6336-463: The major islands (listed above), and individual islets in each atoll. These are just a few: Partial islands, atolls, reefs—those west of Niʻihau are uninhabited except Midway Atoll—form the Northwestern Hawaiian Islands (Leeward Islands): This chain of islands, or archipelago , developed as the Pacific plate slowly moved northwestward over a hotspot in the Earth's mantle at a rate of approximately 32 miles (51 km) per million years. Thus,

6435-531: The mantle source. There are two competing interpretations for this. In the context of mantle plumes, the near-surface material is postulated to have been transported down to the core-mantle boundary by subducting slabs, and to have been transported back up to the surface by plumes. In the context of the Plate hypothesis, subducted material is mostly re-circulated in the shallow mantle and tapped from there by volcanoes. Stable isotopes like Fe are used to track processes that

6534-436: The model. The unexpected size of the plumes leaves open the possibility that they may conduct the bulk of the Earth's 44 terawatts of internal heat flow from the core to the surface, and means that the lower mantle convects less than expected, if at all. It is possible that there is a compositional difference between plumes and the surrounding mantle that slows them down and broadens them. Mantle plumes have been suggested as

6633-400: The most northerly atolls in the world; Kure Atoll , in this group, is the northernmost atoll on Earth. On June 15, 2006, U.S. President George W. Bush issued a proclamation creating Papahānaumokuākea Marine National Monument under the Antiquities Act of 1906 . The national monument, meant to protect the biodiversity of the Hawaiian isles, encompasses all of the northern isles, and is one of

6732-482: The next major event. A tsunami resulting from an earthquake in Japan hit the islands on March 11, 2011. It was relatively minor, but local officials ordered evacuations in preparation for a possible major event. The tsunami caused about $ 30.1 million in damages. Only the two Hawaiian islands furthest to the southeast have active volcanoes: Haleakalā on Maui, and Mauna Loa , Mauna Kea , Kilauea , and Hualalai , all on

6831-404: The northern subduction zone. These thick, buoyant seamounts resisted subduction and caused a reorientation of plate motion. Thus explains the sudden change in plate motion and is supported by the orientation of nearby island chains which also have a sudden bend which mirror the Emperor chain. As shown by Tarduno et al., the hotspot does show some north-south motion, but Yaoling's model shows that for

6930-602: The northwest coast of the island of Hawaii, near the Kona area. The initial earthquake was followed approximately five minutes later by a magnitude 5.7 aftershock . Minor to moderate damage was reported on most of the Big Island. Several major roadways became impassable from rock slides, and effects were felt as far away as Honolulu , Oahu, nearly 150 miles (240 km) from the epicenter . Power outages lasted for several hours to days. Several water mains ruptured. No deaths or life-threatening injuries were reported. On May 4, 2018, there

7029-473: The ocean, and the possibility of an explosive eruption. There is no definitive date for the Polynesian discovery of Hawaii . However, high-precision radiocarbon dating in Hawaii using chronometric hygiene analysis, and taxonomic identification selection of samples, puts the initial such settlement of the Hawaiian Islands sometime between 940-1250 C.E., originating from earlier settlements first established in

7128-409: The originally subducted material creates diverging trends, termed mantle components. Identified mantle components are DMM (depleted mid-ocean ridge basalt (MORB) mantle), HIMU (high U/Pb-ratio mantle), EM1 (enriched mantle 1), EM2 (enriched mantle 2) and FOZO (focus zone). This geochemical signature arises from the mixing of near-surface materials such as subducted slabs and continental sediments, in

7227-601: The plate motion. Another example is the Canary Islands in the northeast of Africa in the Atlantic Ocean. Helium-3 is a primordial isotope that formed in the Big Bang . Very little is produced, and little has been added to the Earth by other processes since then. Helium-4 includes a primordial component, but it is also produced by the natural radioactive decay of elements such as uranium and thorium . Over time, helium in

7326-566: The plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots , such as Hawaii or Iceland , and large igneous provinces such as the Deccan and Siberian Traps . Some such volcanic regions lie far from tectonic plate boundaries , while others represent unusually large-volume volcanism near plate boundaries. Mantle plumes were first proposed by J. Tuzo Wilson in 1963 and further developed by W. Jason Morgan in 1971 and 1972. A mantle plume

7425-412: The plume hypothesis has been challenged and contrasted with the more recent plate hypothesis ("Plates vs. Plumes"). The reason for this is that the mantle-plume hypothesis has not been suitable for making reliable predictions since its introduction in 1971 and has therefore been repeatedly adapted to observed hotspots depending on the situation. Over time, with the growing number of models, the concept of

7524-402: The pressure exerted by rising magma put a great amount of stress on the volcanic flanks. The stress is released when the slope fails, or slips, causing an earthquake. This type of seismicity is unique because the forces driving the system are not always consistent over time, since rates of volcanic activity fluctuate. Seismic hazard near active, seaward volcanic flanks is high, partially because of

7623-422: The seamounts of the Emperor chain suggest motion of the Hawaiian hotspot in Earth's mantle. Tarduno et al. have interpreted that the bend in the seamount chain may be caused by circulation patterns in the flowing solid mantle (mantle "wind") rather than a change in plate motion. There are two distinct interpretations for the cause of the bend in the seamounts of the Emperor chain as previously mentioned. First, that

7722-459: The sense of columnar vertical features that span most of the Earth's mantle, transport large amounts of heat, and contribute to surface volcanism. Under the umbrella of the plate hypothesis, the following sub-processes, all of which can contribute to permitting surface volcanism, are recognised: In addition to these processes, impact events such as ones that created the Addams crater on Venus and

7821-547: The shallow asthenosphere that is thought to be flowing rapidly in response to motion of the overlying tectonic plates. There is no other known major thermal boundary layer in the deep Earth, and so the core-mantle boundary was the only candidate. The base of the mantle is known as the D″ layer , a seismological subdivision of the Earth. It appears to be compositionally distinct from the overlying mantle and may contain partial melt. Two very broad, large low-shear-velocity provinces exist in

7920-707: The source for flood basalts . These extremely rapid, large scale eruptions of basaltic magmas have periodically formed continental flood basalt provinces on land and oceanic plateaus in the ocean basins, such as the Deccan Traps , the Siberian Traps the Karoo-Ferrar flood basalts of Gondwana , and the largest known continental flood basalt, the Central Atlantic magmatic province (CAMP). Many continental flood basalt events coincide with continental rifting. This

8019-413: The southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and typically smaller, due to longer exposure to erosion . The age of the archipelago has been estimated using potassium-argon dating methods. From this study and others, it is estimated that the northwesternmost island, Kure Atoll , is the oldest at approximately 28 million years (Ma); while

8118-406: The southeasternmost island, Hawaiʻi , is approximately 0.4 Ma (400,000 years). The only active volcanism in the last 200 years has been on the southeastern island, Hawaiʻi, and on the submerged but growing volcano to the extreme southeast, Kamaʻehuakanaloa (formerly Loʻihi). The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images and interpretations of

8217-425: The speeds of seismic waves, but unfortunately so do composition and partial melt. As a result, wave speeds cannot be used simply and directly to measure temperature, but more sophisticated approaches must be taken. Seismic anomalies are identified by mapping variations in wave speed as seismic waves travel through Earth. A hot mantle plume is predicted to have lower seismic wave speeds compared with similar material at

8316-427: The summer months the average temperature is about 84 °F (29 °C), in the winter months it is approximately 79 °F (26 °C). As the temperature is relatively constant over the year the probability of dangerous thunderstorms is approximately low. Mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle , hypothesized to explain anomalous volcanism. Because

8415-411: The surface and erupts to form hotspots. The most prominent thermal contrast known to exist in the deep (1000 km) mantle is at the core-mantle boundary at 2900 km. Mantle plumes were originally postulated to rise from this layer because the hotspots that are assumed to be their surface expression were thought to be fixed relative to one another. This required that plumes were sourced from beneath

8514-724: The surface. Numerical modelling predicts that melting and eruption will take place over several million years. These eruptions have been linked to flood basalts , although many of those erupt over much shorter time scales (less than 1 million years). Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly

8613-525: The theory are linear volcanic chains, noble gases , geophysical anomalies, and geochemistry . The age-progressive distribution of the Hawaiian-Emperor seamount chain has been explained as a result of a fixed, deep-mantle plume rising into the upper mantle, partly melting, and causing a volcanic chain to form as the plate moves overhead relative to the fixed plume source. Other hotspots with time-progressive volcanic chains behind them include Réunion ,

8712-556: The upper atmosphere is lost into space. Thus, the Earth has become progressively depleted in helium, and He is not replaced as He is. As a result, the ratio He/ He in the Earth has decreased over time. Unusually high He/ He have been observed in some, but not all, hotspots. This is explained by plumes tapping a deep, primordial reservoir in the lower mantle, where the original, high He/ He ratios have been preserved throughout geologic time. Other elements, e.g. osmium , have been suggested to be tracers of material arising from near to

8811-480: The upper mantle and above, with an emphasis on plate tectonics as the driving force of magmatism. The plate hypothesis suggests that "anomalous" volcanism results from lithospheric extension that permits melt to rise passively from the asthenosphere beneath. It is thus the conceptual inverse of the plume hypothesis because the plate hypothesis attributes volcanism to shallow, near-surface processes associated with plate tectonics, rather than active processes arising at

8910-457: The uprising material experiences during melting. The processing of oceanic crust, lithosphere, and sediment through a subduction zone decouples the water-soluble trace elements (e.g., K, Rb, Th) from the immobile trace elements (e.g., Ti, Nb, Ta), concentrating the immobile elements in the oceanic slab (the water-soluble elements are added to the crust in island arc volcanoes). Seismic tomography shows that subducted oceanic slabs sink as far as

9009-523: The volcanism. Kīlauea had been erupting nearly continuously since 1983 when it stopped August 2018. Almost all of the magma of the hotspot has the composition of basalt , and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase . Nephelinite is exposed on the islands but is extremely rare. The majority of eruptions in Hawaiʻi are Hawaiian-type eruptions because basaltic magma

9108-541: The volcano and subsidence of the seafloor cause the volcano to gradually diminish. As the volcano sinks and erodes, it first becomes an atoll island and then an atoll . Further subsidence causes the volcano to sink below the sea surface, becoming a seamount and/or a guyot . From the 1960s to the 1980s, the seamounts were intensively bottom trawled . Trawling has continued since then at lower rates, particularly by Japanese ships seeking Pentaceros wheeleri . The North Pacific Fisheries Commission regulates fishing in

9207-490: The west, could explain the large bend present in the Hawaiian - Emperor Seamount Chain. The chain has been produced by the movement of the ocean crust over the Hawaiʻi hotspot , an upwelling of hot rock from the Earth's mantle . As the oceanic crust moves the volcanoes farther away from their source of magma, their eruptions become less frequent and less powerful until they eventually cease altogether. At that point erosion of

9306-576: The western USA, the East African Rift valley, and the Rhine Graben . Under this hypothesis, variable volumes of magma are attributed to variations in chemical composition (large volumes of volcanism corresponding to more easily molten mantle material) rather than to temperature differences. While not denying the presence of deep mantle convection and upwelling in general, the plate hypothesis holds that these processes do not result in mantle plumes, in

9405-420: The world. In August 2010, UNESCO 's World Heritage Committee added Papahānaumokuākea to its list of World Heritage Sites . On August 26, 2016, former President Barack Obama greatly expanded Papahānaumokuākea, quadrupling it from its original size. The Hawaiian Islands are tropical but experience many different climates, depending on altitude and surroundings. The islands receive most rainfall from

9504-522: Was a 6.9 earthquake in the zone of volcanic activity from Kīlauea . Earthquakes are monitored by the Hawaiian Volcano Observatory run by the USGS . The Hawaiian Islands are subject to tsunamis , great waves that strike the shore. Tsunamis are most often caused by earthquakes somewhere in the Pacific. The waves produced by the earthquakes travel at speeds of 400–500 miles per hour (600–800 km/h) and can affect coastal regions thousands of miles (kilometers) away. Tsunamis may also originate from

9603-423: Was essentially stationary as the Pacific tectonic plate drifted in a northwesterly direction, leaving a trail of increasingly eroded volcanic islands and seamounts in its wake. An otherwise inexplicable kink in the chain marks a shift in the movement of the Pacific plate some 47 million years ago, from a northward to a more northwesterly direction, and the kink has been presented in geology texts as an example of how

9702-779: Was illegally deposed and placed under house arrest by businessmen (who included members of the Dole family ) with help from the U.S. Marines . The Republic of Hawaii governed for a short time until Hawaii was annexed by the United States in 1898 as the Territory of Hawaii . In 1959, the islands became the 50th American state . The islands are home to a multitude of endemic species. Since human settlement, first by Polynesians , non native trees, plants, and animals were introduced. These included species such as rats and pigs, that have preyed on native birds and invertebrates that initially evolved in

9801-520: Was the movement of the hotspot itself that caused the bend. The issue continues to remain under academic debate. All of the volcanoes in this part of the chain have long since subsided below sea level, becoming seamounts and guyots . Many of the volcanoes are named after former emperors of Japan . The seamount chain extends to the West Pacific , and terminates at the Kuril–Kamchatka Trench ,

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