Submarine volcano

A submarine volcano is a column in the earth's crust, which is located below the sea surface and penetrates through the magma to the surface.

The submarine, that is, undersea volcanoes are on the one hand, the most common on the earth occurring volcanoes. On the other hand, they are due to their location, which can be located up to several thousand meters below the surface, even those who iA are still the least studied.

Undersea volcanoes at mid-ocean ridges are estimated to account for 75 % of the annual emissions of magma on the earth. On the ocean ridges such as the Mid-Atlantic Ridge is also found particularly many columns volcanoes that are more prone to effusive eruptions.

Although most of these volcanoes are located deep under the sea, but some are in relative proximity to it and can use it during an outbreak because of gas and ash emissions endanger adjacent inhabited areas.

• 3.1 eruptions and hazard potential
• 3.2 Research examples 3.2.1 Mediterranean 3.2.1.1 volcano Kolumbos
• 3.2.1.2 Tyrrhenian Sea

• 3.2.2.1 Azores
• 3.2.2.2 Iceland
• 3.2.2.3 lowest-lying black smokers in the Cayman Trench

• 3.2.4.1 Japan
• 3.2.4.2 eruption of a submarine volcano near Tonga
• 3.2.4.3 Mapping before Kamchatka
• 3.2.4.4 Development of a submarine volcano and its surroundings in the Marianas

• 6.1 Photos and Videos
• 6.2 Scientific contributions
• 6.3 Press reports

Emergence of a submarine volcano

The magmas are formed probably at the boundary between Earth's mantle and crust, the oceans is about 10 km depth. The movements of the continental plates cause at points of the earth's crust is particularly thin and ridged columns. This is especially true for the ocean ridges such as the Mid-Atlantic Ridge, where two plates diverge, but also for the subduction zones, as found, for example, on the Pacific Ring of Fire, where one plate slides under another. Hot spots also, which are independent of plate movements that cause volcanic eruptions in the sea, as can be observed for example in the Hawaiian Islands.

At these locations, it is particularly easy to ascend for magmas. This infiltrate into other layers and initially form intrusions on which to build the actual volcanoes. Because of the rapid cooling by the 1-2 ° cold sea water as well as the strong pressure assumes a considerable part of the ejected lava tube shape. It is pillow lava. The center of the submarine volcanoes can be found as well as to those on the surface a large amount of feed passages and one to several magma chambers. Through this, the magma rises to the surface and with decreasing pressure, gas bubbles form in it. These in turn cause explosive eruptions underwater at depths of about 1000 m below the sea surface to just below this. This form pyroclastic materials, but also fine to very fine glass particles, which in turn represent the fairly erodible slopes of the volcano. This composition of very loose material explains the frequency of landslides in submarine volcanoes and ocean islands (see eg Tenerife ).

Types of submarine volcanoes

Seamount

Most submarine volcanoes called seamounts. They represent the most common occurring on Earth Vulkanart, with only about one million in the Pacific. They are mainly located in the vicinity of mid-ocean ridges and subduction zones, where they can form obstacles outright, where hang the plates, leading to violent earthquakes.

Seamounts, which are close to mid-ocean ridges, preferably promote lavas tholeiitischer composition, the further they are away from the back the more alkaline lavas are produced.

Guyot

A Guyot is a special type of Seamount. Recognized for its truncated cone shape.

There are former seamounts that have been shaped by erosion and are often covered with fossil coral reefs. Some of them have also received through the formation of a caldera their special shape.

Ocean islands

Only in cases where the eruption rate exceeds the erosion by far, is finally able to make ocean islands, as one could observe it, for example, from 1963 in the case of Surtsey.

Exploration of submarine volcanoes

Eruptions and hazard potential

Research into submarine volcanoes is expensive and complex.

They are often not easy to discover. This is, inter alia, the fact that its eruptions are damped. The thermal conductivity of the water causes a rapid cooling of the ejection materials so that the magma turns much faster than in air in volcanic glass. Depending on the depth of the overlying them water surface increases the pressure bearing on them pressure. This dampens the explosiveness of the eruption to a considerable extent, so that the outbreaks with increasing water depth are the harder noticeable.

Research examples

Mediterranean

Volcano Kolumbos

A historical example with regard to the surprising discovery of a submarine volcano, the volcano Kolumbos in the Aegean. It was discovered in 1650, than in an explosive eruption of Santorini Kolumbos 70 people were killed.

Tyrrhenian Sea

In Italy is planning further investigations of submarine volcanoes in the Tyrrhenian Sea, for example, the Marsili, including because of possible edge collapses and their tsunami potential.

An American expedition in 2006 found traces of lead, which could be followed to Australia, the underwater volcano Marsili, about 350 km off the west coast of Italy.

Atlantic

Azores

A German - Portuguese project, and the Alfred Wegener Institute participates, mapped and monitored seamounts in the Azores.

Iceland

In Iceland, one is interested in the north and southwest of Iceland for the submarine continuations of the Mid-Atlantic Ridge. This relates not only to the Tjörnesfrakturzone and the Kolbeinseyrücken in the north of the island, especially the Reykjanesrücken, the Iceland in southern upstream part. It has a large active submarine volcano there discovered, for example, in 2007 about 50 km away from the main island, which was called Njörður.

Lowest-lying black smokers in the Cayman Trench

A British research expedition discovered with remote-controlled robot submersibles the deepest black smokers that have been found so far. You are near the Cayman Islands in Cayman trench at a depth of 5000 m.

The expedition with the ship RRS James Cook is part of a project funded by the UK Natural Environment Research Council UK project, which began in Trinidad on 21 March 2010.

Gakkel Ridge 85 ° E

A striking accumulation of strong earthquakes (up to over 5 on the Richter scale ) presented in 1999 to the so-called Gakkel Ridge, Arctic continuation of the Mid-Atlantic Ridge between Siberia and Greenland, firmly. It was 200 earthquake of this strength within 7 months. The SCICEX expedition checked the area in time twice and discovered fresh lava flows at a submarine volcano at 85 ° E. The event attracted the attention of geoscientists, not least through the long period over which it extended. Previous findings documented submarine eruptions only over periods of up to about 4 weeks.

The Amore -2001 expedition of the Alfred Wegener Institute in 2001 was able to demonstrate current eruptive activity by tremor measurements and recordings of explosion noises on the seabed at the same volcanic complex. Another international expedition to the same volcanic complex in 2007 captured more accurate data.

Pacific

Japan

A submarine volcano called Fukutoku - Okanoba erupted removed about 1300 km from Tokyo before the Japanese coast on July 2, 2005. The volcano was known for regular eruptions in the 20th century, most recently in 1992. Too, he succeeded in 1986 to form an island, but only briefly had stock before it was eroded by the sea.

Eruption of a submarine volcano near Tonga

An explosive eruption ereigenete by March 17, 2009 at a submarine volcano on the island of Tonga in the Pacific Ocean, about 10 km from the main island of Tongatapu. The eruption, which, inter alia, produced pyroclastic flows, a new island was born.

Mapping before Kamchatka

2009 succeeded a German - Russian research team under the scientific direction of the Federal Institute for Geosciences and Natural Resources ( BGR) 2700 km sea floor to measure the undersea volcanoes in the Emperor Seamount chain - from the Russian Kamchatka Peninsula. The expedition in the Pacific Northwest on the German research vessel "Sonne " lasted three weeks.

The extinct volcano rising to 4500 meters above the sea floor. The elastic crust bends among them. The scientists found a 700- km-long rupture zone. On the escarpment, it was observed a difference in altitude of 1000 m between the plates. The volcanoes that were originally formed in the area of ​​the Hawaiian archipelago are migrated to the Pacific Plate to the north- west to Kamchatka and dive in slowly under the North American Plate from where she and Earthquake decisive influence on the Kamchatka Peninsula, the geology, the volcanic activity exercise.

Development of a submarine volcano and its surroundings in the Marianas

In the area of the Mariana Islands in the Pacific, an international research team led by the Oregon State University was able to follow the development of a submarine volcano, which they named NW Rota -1. The approximately 520 -meter distance below the ocean volcano was discovered in 2004 and observed in 2006 in more detail. The volcano seems to be constantly in action, and had built up in the meantime, a 40 m high and 300 m wide crater. An underwater microphone had delivered the evidence of the constant eruption activity.

Scientists also studied the existing fauna of the volcano and discovered several new species. In addition, it was noted that apparently had higher levels of activity with the environment of the mountain more attractive to animals such as crabs, shrimp, snails, and barnacles. The animals feed on bacteria that colonize the volcanic vent. They are adapted to living conditions that would be toxic to others.

One of the Garnelarten, a previously unknown species that is in adulthood for predator and scavenger, among other things, to feeds from other types of shrimps and fish killed by the volcano.

Loihi, the next Hawaiian island?

The submarine volcano Loihi is above the hot spot of Hawaii and is likely to form the next local island. However, this will take some time, the summit of the mountain is underwater but currently about 1000 m below the sea surface.

The U.S. government research institution NOAA has the volcano closely examined. It maintains in Hawaii a specialized underwater research center.

It was found that the volcano has three summit crater. Numerous hydrothermal vents are found on the walls of the youngest crater that was formed in 1996. The water flowing out of them -gas mixture is hot up to 200 °.