What are underwater volcanoes like the ones that erupted in Tonga?
(CNN Español) – the volcano eruption on saturday From the volcano Hung Tonga – Hung Hapai, located near Tonga, put the issue of submarine volcanoes at the center of the discussion. why?
First of all, this volcano is a submarine-type, according to Global Volcanoes Program From the Smithsonian Institution. What is more, Skin rash It may have been the largest number recorded anywhere on the planet in more than 30 years, according to experts.
The explosion was so powerful that images from space captured the explosion in real time, as a huge plume of ash, gas and steam was thrown up to 20 kilometers into the atmosphere, and tsunami waves crashed into the Pacific Ocean. You can see these photos in the following video:
It was a violent explosion That caused a tsunami that hit Hawaii, Japan, and Tongatapu, the largest of the Tonga islands, causing waves to engulf the island nation’s capital.
Its strength is not due to the fact that it is an underwater volcano, but it raises some doubts about this type of volcano.
What are underwater volcanoes?
Simply put, they are underwater volcanoes. according to Oregon State University (OSU for its English acronym), “The most active volcanic system on Earth is hidden under an average water surface of 2,600 metres.”
Why are they the most active?
OSU notes that undersea volcanoes are responsible for nearly three-quarters of Earth’s annual magma production.
The University of Oregon Foundation explains that “the global system of the middle ridges generates approximately 75% of the annual production of magma; it is estimated that 3 cubic kilometers of lava is emitted.” It should be noted that mid-ocean ridges are “submerged mountain ranges or ranges of volcanic origin,” according to seismology chile, nonprofit organization.
Also, the post Geophysics, of the Geophysics Institute of the National Autonomous University of Mexico (UNAM), noted in 2004 that submarine volcanoes account for 80% of the planet’s volcanoes, which somewhat corresponds to the percentage of annual magma production.
How many underwater volcanoes in the world?
OSU states that it is estimated that there are about 4,000 volcanoes per million square kilometers on the bottom of the Pacific Ocean.
So, if you apply this estimate to all of the world’s oceans, says OSU, “there are more than a million underwater volcanoes.”
“Maybe as many as 75,000 of these volcanoes rise more than half a mile[one kilometre]above the ocean floor,” he adds.
How do volcanoes form under water?
As in the case of continental volcanoes (those that can be seen with the naked eye on Earth), submarine volcanoes are more common where tectonic plates move closer or farther away, says Ohio State University.
In fact, tectonic plates are solid, and when they move and interact with each other, they do not deform significantly, except at their edges, where there are very important changes, According to the Mexican Geological Service (SGM).
Therefore, we are talking about divergent edges when tectonic plates move apart and edges converging as they come closer. The SGM adds that these movements of both separation and approach lead to “most of the Earth’s volcanic and seismic activity, as well as the origin of mountain systems.”
In addition to the formation of volcanoes through the movements of tectonic plates, there is also the formation of submarine volcanoes in the so-called “hot spots”, which are “channels, immobile or relatively immobile, connecting the surface to the depths (up to 2900 km) of the Earth and in which vertical movement of magma occurs”, according to University of Costa Rica.
“Hotspots leave linear ‘footprints’ of seamounts across ocean basins and build some of the largest volcanoes on Earth,” USO . explains.