Hawaiian–Emperor Seamount Chain
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The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
that reaches above sea level in
Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...
. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening
seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...
s,
atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most ...
s, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about from the
Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ula ...
off the coast of the
Kamchatka peninsula The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...
in the far northwest Pacific to the
Kamaʻehuakanaloa Seamount Kamaʻehuakanaloa Seamount (previously known as Lōʻihi) is an active submarine volcano about off the southeast coast of the island of Hawaii. The top of the seamount is about below sea level. This seamount is on the flank of Mauna Loa, the ...
(formerly Lōʻihi), the youngest volcano in the chain, which lies about southeast of the Island of Hawaiʻi.


Regions

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 Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...
. 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 yearsPre-press version
to 5.1 million years. The island of Hawaii is composed of five volcanoes, of which four ( Kilauea,
Mauna Loa Mauna Loa (, ; ) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. Mauna Loa is Earth's largest active volcano by both mass and volume. It was historically considered to be the largest ...
, Hualalai, and
Mauna Kea Mauna Kea (, ; abbreviation for ''Mauna a Wākea''); is a dormant Shield volcano, shield volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in Hawaii a ...
) are active. The island of
Maui Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui is one of ...
has one active volcano,
Haleakalā Haleakalā (; Hawaiian: ), or the East Maui Volcano, is a massive, active shield volcano that forms more than 75% of the Hawaiian Islands, Hawaiian Island of Maui. The western 25% of the island is formed by another volcano, Mauna Kahalawai, als ...
.
Kamaʻehuakanaloa Seamount Kamaʻehuakanaloa Seamount (previously known as Lōʻihi) is an active submarine volcano about off the southeast coast of the island of Hawaii. The top of the seamount is about below sea level. This seamount is on the flank of Mauna Loa, the ...
continues to grow offshore of Hawaii island, and 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 The Northwestern Hawaiian Islands also known as the Leeward Hawaiian Islands, are a series of islands and atolls located northwest of Kauai and Niihau, Niihau in the Hawaiian Islands, Hawaiian island chain. Politically, these islands are part of ...
, 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 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 George Walker Bush (born July 6, 1946) is an American politician and businessman who was the 43rd president of the United States from 2001 to 2009. A member of the Bush family and the Republican Party (United States), Republican Party, he i ...
issued a proclamation creating
Papahānaumokuākea Marine National Monument The Papahānaumokuākea Marine National Monument (PMNM) (roughly ) is a World Heritage Site, World Heritage listed National monument (United States), U.S. national monument encompassing of ocean waters, including ten islands and atolls of th ...
under the Antiquities Act of 1906. The national monument, meant to protect the biodiversity of the Hawaiian isles,All of the islands in this part of the chain are administered by the state of Hawaii, with the exception of
Midway Atoll Midway Atoll (colloquialism, colloquial: Midway Islands; ; ) is a atoll in the North Pacific Ocean. Midway Atoll is an insular area of the United States and is an Insular area#Unorganized unincorporated territories, unorganized and unincorpo ...
, which is administered by the U.S. Fish and Wildlife Service.
encompasses all of the northern isles, and is one of 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 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, a
subduction zone Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...
at the border of
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
.


Formation

The oldest confirmed age for one of the Emperor Seamounts is 81 million years, for Detroit Seamount. However,
Meiji Seamount Meiji Seamount, named after Emperor Meiji, the 122nd Emperor of Japan, is the oldest seamount in the Hawaiian-Emperor seamount chain, with an estimated age of 82 million years. It lies at the northernmost end of the chain, lies off the coast of ...
, located to the north of Detroit Seamount, is likely somewhat older. In 1963, geologist
John Tuzo Wilson John Tuzo Wilson (October 24, 1908 – April 15, 1993) was a Canadian geophysicist and geologist who achieved worldwide acclaim for his contributions to the theory of plate tectonics. He added the concept of ''hot spots'', a volcanic region hott ...
hypothesized the origins of the Hawaiian–Emperor seamount chain, explaining that they were created by a hotspot of volcanic activity that 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 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 the hotspot itself may have moved with time. Some evidence comes from analysis of the orientation of the ancient magnetic field preserved by
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...
in ancient lava flows sampled at four seamounts: this evidence from
paleomagnetism Paleomagnetism (occasionally palaeomagnetism) is the study of prehistoric Earth's magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain ...
shows a more complex history than the commonly accepted view of a stationary hotspot. If the hotspot had remained above a fixed
mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic ho ...
during the past 80 million years, 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 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 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 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 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 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, 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 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 the west, could explain the large bend present in the Hawaiian - Emperor Seamount Chain.


Aging

The chain has been produced by the movement of the
ocean crust Oceanic crust is the uppermost layer of the oceanic portion of the Plate tectonics, tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike (geology), dike complex, and the lower oceanic crust, composed of troct ...
over the
Hawaii hotspot The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the ...
, an
upwelling Upwelling is an physical oceanography, oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted sur ...
of hot rock from the
Earth's mantle Earth's mantle is a layer of silicate mineral, silicate rock between the Earth's crust, crust and the Earth's outer core, outer core. It has a mass of and makes up 67% of the mass of Earth. It has a thickness of making up about 46% of Earth's ...
. 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 Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
of the volcano and
subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...
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 An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most ...
. Further subsidence causes the volcano to sink below the sea surface, becoming a
seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...
and/or a
guyot In marine geology, a guyot (), also called a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed . Guyots are most commonly fo ...
.


Economic activity

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 the area.


See also

*
Isostasy Isostasy (Greek wikt:ἴσος, ''ísos'' 'equal', wikt:στάσις, ''stásis'' 'standstill') or isostatic equilibrium is the state of gravity, gravitational mechanical equilibrium, equilibrium between Earth's crust (geology), crust (or lithosph ...
* Kodiak–Bowie Seamount chain *
New England Seamounts The New England Seamounts is a chain of over twenty underwater extinct volcanic mountains known as seamounts. This chain is located off the coast of Massachusetts in the Atlantic Ocean and extends over from the edge of Georges Bank. Many of th ...
*
Oceanic trench Oceanic trenches are prominent, long, narrow topography, topographic depression (geology), depressions of the seabed, ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers ...
* Pacific-Kula Ridge *
Plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
*
Timeline of the far future While the future cannot be predicted with certainty, present understanding in various scientific fields allows for the prediction of some far-future events, if only in the broadest outline. These fields include astrophysics, which studies ho ...
* Vitória-Trindade Ridge


References

Informational notes Citations Further reading * * * *
USGS, "The long trail of the Hawaiian hotspot"


: August 14, 2003 * ttps://web.archive.org/web/20080819183123/http://wwwhvo.wr.usgs.gov/volcanowatch/1995/95_09_08.html Evolution of Hawaiian Volcanoesfrom the USGS.
Ken Rubin, "The Formation of the Hawaiian Islands"
with tables and diagrams illustrating the progressive age of the volcanoes.

{{DEFAULTSORT:Hawaiian-Emperor seamount chain Seamount chains Seamounts of the Pacific Ocean Volcanism of Oceania Volcanism of the Pacific Ocean Volcanism of Hawaii Guyots Landforms of Hawaii Physical oceanography Volcanoes of Hawaii Hotspot tracks Cretaceous volcanism Cretaceous Oceania Cenozoic volcanism Cenozoic Hawaii Cenozoic Oceania