Did you know that Hawaii’s Mauna Kea or White Mountain is the world’s tallest peak, measuring 16,400 m (47,000 feet) from base to summit? And that underwater volcanoes account for 75% of annual magma output? Just like Mauna Kea’s height, with 10,000 m (33,500 feet) under sea level, underwater volcanoes and their eruptions often go unnoticed. And because the usual signs like rumbling and smoke are harder to detect, it is all the more spectacular when an underwater volcano visibly erupts. Follow us around the globe for some of the most stunning sights.
It is estimated that there are currently 5,000 active underwater volcanoes worldwide; of various sizes, standing alone or forming ridges with other volcanoes, of which the highest ones will rise above the surface as islands. The submerged part of the Hawaiian Islands, for example, is one of the largest and longest volcanic ridges – more than 2,400 km (1,500 miles) long.
Image: Zina Deretsky, NSF
This diagram shows how a submarine volcano’s lava, ash and debris can settle on top of it, thus raising its peak, often above sea level. Or, a big rock or piece of lava can lodge itself in the volcano’s crater – hopefully after all the pressure has been released!
As underwater fissures in the earth’s surface, most submarine volcanoes are located near areas of tectonic plate movement. Clusters of terrestrial volcanoes therefore point to hotbeds of underwater volcanic activity as well, like the places portrayed here around Hawaii, California, Iceland, Japan, New Zealand, the Caribbean and Antarctica.
Image: Maui Boat Rental
1. Molokini Crater, Hawaii
Today, Molokini Crater in Maui County, Hawaii is a crescent shaped “island” popular with scuba divers, snorkelers and seabirds alike, but it used to be a fully round, volcanic crater. One can just imagine the underwater volcano in its heyday, forming a few new islands through eruption.