Hawaiian–Emperor seamount chain

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Hawaii - Emperor chain of islands in the middle

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The Hawaiian - Emperor island chain ( in German literature sometimes referred to as Hawaii - Emperor - back) is an island chain of shield volcanoes in the Pacific Ocean, which extend only partially to above sea level. It consists of over 129 major volcanoes, extending over a length of 6,100 kilometers, and are up to 89 million years old. The island chain is often cited as a prime example of the so-called " hot-spot" volcanism.

Geographical location

The north-south string of pearls extending 2800 km long north - Emperor island chain makes a bend and enters the southeast extending, also arranged like pearls, Hawaiian island chain. This is sometimes called the Hawaii - back. The island chain of volcanoes thus ranges from Aleutengraben in the north, where the Pacific plate dives under the North American Plate to Hawaii.

Formation

The arrangement and the increasing age of the seamounts of the Hawaiian - Emperor chain of islands declared for the first time John Tuzo Wilson with a more than 80 million -year-long movement of the Pacific tectonic plate over a stationary hotspot then assumed away. Currently available geophysical studies show anomalies down to the lower mantle ( at least 1200 km depth ). The reason for this anomaly could be between 200 to 650 million years before present subducted oceanic crust.

Due to the continental plate drift, the active volcanism moved at a speed of about 8-10 cm per year.

Knick- controversy

The kink that would show a change in the motion of the Pacific plate in front of about 43 million years after a theory is the result of the collision of the Indian subcontinent with the Eurasian plate. The speed of India would have declined to the north, the subcontinent rotated counterclockwise and so it would have been a change in motion of the Pacific tectonic plate.

For several years there has been some scientific evidence for the hypothesis that hot spots are deflected by the convective motions in the mantle and therefore can not be considered fixed in relation to the movements of plate tectonics. Then the hot spot would be in the period from 81 bis 47 million years ago migrated at a rate of 40 millimeters per year southward and would have greatly reduced its movement. The collision of the Indian subcontinent with the Eurasian plate did not come with it, at least as a direct cause of the kink in question.

The mountains under the sea

The northernmost submarine volcano is the Meiji Seamount, north at about 53 ° latitude and 165 ° west longitude. It is about 2000 m above the sea floor lying plateau, about 85 million years old. The closes south of Detroit Rise Seamount, with an age of about 81 million years.

Many of these submarine volcanoes were after a Tennō (Japanese emperor Kammu, Kimmei, Koko, Meiji, Nintoku ojin, Suiko, Yomei, Yūryaku ) or persons named with these related ( Jingū ).

The islands of Kure Atoll and 80 km further east, the Midway Islands at 28 ° N latitude and 177 ° west longitude, are the first islands in the Northwestern Hawaiian Islands. These are to close to the water surface reaching or even piercing volcanoes. The Kure Island ( main island of Kure Atoll ) is thus the oldest island of the Hawaiian - Emperor island chain with an age of about 30 million years ago. The next younger islands are the Midway Islands with an age of about 28 million years ago. Originally, the Midway Islands were a large shield volcano, which reached up to the water surface or even higher. Over time, the volcano has been slowly eroded, leaving only two small main islands and several small islands, as well as a 160 m high today Atoll 6 km in diameter can be seen.

The youngest volcano Loihi located 35 kilometers south-east of the island of Hawaii. The largest volcano in the Hawaii - Emperor seamount chain is the island of Mauna Kea, the under water up to the top of the foot is about 10,205 feet high. Over water it reaches a height of 4,205 m.