Seamount facts for kids

Bathymetric showing part of Davidson Seamount. The dots indicate significant coral nurseries.

Diagram of a submarine eruption. (key: 1. Water vapor cloud 2. Water 3. Stratum 4. Lava flow 5. Magma conduit 6. Magma chamber 7. Dyke 8. Pillow lava) Click to enlarge.

A seamount is a mountain rising from the ocean sea floor. It does not reach to the water's surface (sea level), and so is not an island. These are usually formed from submarine volcanoes. They are usually 1,000–4,000 metres (3,000–13,000 ft) in height from the sea floor.

The peaks are often found hundreds to thousands of metres below the surface, and so are in the deep sea. There are an estimated 100,000 seamounts around the globe, but only a few have been studied. Seamounts come in all shapes and sizes, and follow a distinctive pattern of growth, activity, and death. In recent years, several active seamounts have been observed, for example Loihi seamount in the Hawaiian–Emperor seamount chain.

Seamounts are one of the most common oceanic ecosystems in the world. Interactions between seamounts and underwater currents, and their raised position in the water, attract plankton, corals, fish, and cetacea alike. Their effect has been noted by the commercial fishing industry, and many seamounts support extensive fisheries. There are concerns about the effect of fishing on seamount ecosystems. There are well-documented cases of stock decline. 95% of ecological damage is done by bottom trawling, which literally scrapes whole ecosystems off seamounts.

Most seamounts are not yet to be studied, or even mapped. Bathymetry and satellite altimetry are two technologies used to collect data. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses. As they get older, water pressure pushes water into their sides, causing landslides that may cause massive tsunamis.

Related pages

• Hawaiian–Emperor seamount chain
• Saikaidō Seamounts
• Guyot

Images for kids

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  Pillow lava, a type of basalt flow that originates from lava-water interactions during submarine eruptions

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  Grenadier fish (Coryphaenoides sp.) and bubblegum coral (Paragorgia arborea) on the crest of Davidson Seamount. These are two species attracted to the seamount; Paragorgia arborea in particular grows in the surrounding area as well, but nowhere near as profusely.

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  Because of overfishing at their seamount spawning grounds, stocks of orange roughy (Hoplostethus atlanticus) have plummeted; experts say that it could take decades for the species to restore itself to its former numbers.

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  Coral earrings of this type are often made from coral harvested off seamounts.

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  Graph showing the rise in global sea level (in mm) as measured by the NASA/CNES oceanic satellite altimeter TOPEX/Poseidon (left) and its follow-on mission Jason-1

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  USS San Francisco in dry dock in Guam in January 2005, following its collision with an uncharted seamount. The damage was extensive and the submarine was just barely salvaged.

See also

In Spanish: Monte submarino para niños