Submarine volcano

Source: Wikipedia, the free encyclopedia.
Not to be confused with Subaqueous volcano, a volcano formed beneath freshwater that never builds above lake level.
For mountains rising from the ocean seafloor, see Seamount. For related geological features, see Mid-ocean ridge and Hotspot (geology).
Scheme of a submarine eruption.
  1. Water vapor cloud
  2. Water
  3. Stratum
  4. Lava flow
  5. Magma conduit
  6. Magma chamber
  7. Dike
  8. Pillow lava
Pillow lava formed by a submarine volcano
NOAA exploration video showing remnants of underwater tar volcanoes.
Circular plumes from a submarine eruption near Tonga

Submarine volcanoes are underwater vents or fissures in the

eruption. The total number of submarine volcanoes is estimated to be over one million (most are now extinct) of which some 75,000 rise more than 1 kilometre (0.62 mi) above the seabed.[1] Only 119 submarine volcanoes in Earth's oceans and seas are known to have erupted during the last 11,700 years.[2][3]

Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes.

Effect of water on volcanoes

The presence of water can greatly alter the characteristics of a volcanic eruption and the explosions of underwater volcanoes in comparison to those on land.

For instance, water causes magma to cool and solidify much more quickly than in a terrestrial eruption, often turning it into volcanic glass. The shapes and textures of lava formed by submarine volcanoes are different from lava erupted on land. Upon contact with water, a solid crust forms around the lava. Advancing lava flows into this crust, forming what is known as pillow lava.

Below ocean depths of about 2,200 metres (7,200 ft) where the pressure exceeds the

hydrophones.[citation needed
]

The critical temperature and pressure increase in solutions of salts, which are normally present in the seawater. The composition of aqueous solution in the vicinity of hot basalt, and circulating within the conduits of hot rocks, is expected to differ from that of bulk water (i.e., of sea water away from the hot surfaces). One estimation is that the critical point is 407 °C (765 °F) and 29.9 MPa, while the solution composition corresponds to that of approximately 3.2% of NaCl.[4]

Research

Scientists still have much to learn about the location and activity of underwater volcanoes. In the first two decades of this century, NOAA's

black smoker
chimneys and even marine life adapted to this deep, hot environment.

Research from the ROV KAIKO off the coast of Hawaii has suggested that pahoehoe lava flows occur underwater, and the degree of the submarine terrain slope and rate of lava supply determine the shape of the resulting lobes.[5]

In August 2019, news media reported a large

volcanic plume in satellite images.[7] This discovery will help scientists better predict for the precursors of a submarine eruption, such as low-frequency earthquakes or hydrophone data, using machine learning.[7]

Seamounts

Many submarine volcanoes are

extinct volcanoes that rise abruptly from a seafloor of 1,000 metres (3,300 ft) - 4,000 metres (13,000 ft) depth. They are defined by oceanographers as independent features that rise to at least 1,000 metres (3,300 ft) above the seafloor. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea.[8] An estimated 30,000 seamounts occur across the globe, with only a few having been studied.[citation needed
] However, some seamounts are also unusual. For example, while the summits of seamounts are normally hundreds of meters below sea level, the Bowie Seamount in Canada's Pacific waters rises from a depth of about 3,000 metres (9,800 ft) to within 24 metres (79 ft) of the sea surface.[citation needed]

Identifying types of eruptions by sounds

Deepest ever filmed submarine volcano, West Mata, May 2009.[9]

There are two types of sound generated by submarine eruptions: One created by the slow release and bursting of large lava bubbles, while quick explosions of gas bubbles create the other one. Using this method to be able to distinguish the two can help measure the related affects on marine animals and ecosystems, the volume and composition of the lava flow can also be estimated and built into a model to extrapolate potential effects.

Scientists have connected sounds to sights in both types of eruptions. In 2009, a video camera and a hydrophone were floating 1,200 metres (3,900 ft) below sea level in the Pacific Ocean near Samoa, watching and listening as the West Mata Volcano erupted in several ways. Putting video and audio together let researchers learn the sounds made by slow lava bursting and the different noises made by hundreds of gas bubbles.[10][11]

See also

References

  1. ^
    ISBN 978-1-4051-2699-1
    .
  2. ^ Venzke, E., ed. (2013). "Holocene Volcano List". Global Volcanism Program Volcanoes of the World (version 4.9.1). Smithsonian Institution. Retrieved 18 November 2020.
  3. ^ Venzke, E., ed. (2013). "How many active volcanoes are there?". Global Volcanism Program Volcanoes of the World (version 4.9.1). Smithsonian Institution. Retrieved 18 November 2020.
  4. ^ Michael E. Q. Pilson, "An Introduction to the Chemistry of the Sea", 2nd edition. Cambridge University Press, 2013.
  5. ISSN 0091-7613
    .
  6. ^ Guardian Staff (2019-08-25). "Massive pumice 'raft' spotted in the Pacific could help replenish Great Barrier Reef". the Guardian. Retrieved 2021-03-19.
  7. ^ a b "Satellite Sleuthing Detects Underwater Eruptions". Eos. 31 March 2020. Retrieved 2021-03-19.
  8. ^ Nybakken, James W. and Bertness, Mark D., 2005. Marine Biology: An Ecological Approach. Sixth Edition. Benjamin Cummings, San Francisco
  9. ^ "Scientists Discover and Image Explosive Deep-Ocean Volcano". NOAA. 2009-12-17. Retrieved 2009-12-19.
  10. ^ Scientificamerican.com 2015-04-22 Undersea Volcano Explodes as Scientists Watch
  11. doi:10.1002/2014GL062603
    .

External links

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