Submarine volcanoes are less dangerous than land volcanoes.
Submarine volcanoes, as the name suggests, are volcanoes that sit under water on the ocean floor. Despite being submerged, these volcanoes are active and productive, with an estimated 75 percent of the yearly magma output being spewed from submarine volcanoes. Much about submarine volcanoes remains to be learned, with a governmental agency taking the lead in this study, but it is recognized that submarine volcanoes have less devastating results than land volcanoes.
Location
Submarine volcanoes in all shapes and sizes are found across the world from Hawaii and California to Iceland, Japan, New Zealand and Antarctica. Worldwide, there are an estimated 5,000 active submerged volcanoes, with the highest volcanoes or volcanoes in shallow water rising above sea level. Most submerged volcanoes, however, are located on ocean ridges, which are underwater mountain ranges that form due to the movement of tectonic plates.
Difference
When a submarine volcano erupts the result is different -- and usually less dramatic -- than the eruption of a land volcano. Unless the volcano breaks sea level, upon an eruption lava immediately comes into contact with ocean water. The water acts to cool the lava and to transform the lava into a solid state as rubble or sand. This debris then works its way to the ocean floor. Hawaii's Punalu'u Black Sand Beach is an example of the debris produced by a submarine volcano.
Danger
Volcanoes are dangerous, but when compared to land volcanoes, submarine volcanoes pose less of a threat to human life. Since the volcano sits far below the ocean's surface, even a major eruption may not be detected from above. Nonetheless, care must be taken when exploring areas surrounding a submarine volcano. Since 1650, when the Kolumbo submarine volcano erupted, killing at least 70 people on the nearby Greek island of Santorini, submerged volcanoes have been known to be deadly.
NOAA
The National Oceanic and Atmospheric Administration (NOAA) funds scientific expeditions worldwide to learn more about submarine volcanoes, as there is still much to be understood about them. For example, the VENTS program has been established in order to learn how submarine volcanoes affect the ocean's ecosystems. NOAA not only explores past eruptions, but now directly observes eruptions as they occur and uses technology to set up long-term monitoring of submerged volcanoes.
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