North of Japan lies the underwater volcano Kaitoku. It is located about 100 meters below the surface of the water, and in the image from January 2023, one of the three peaks of the volcano is active. © IMAGO/NASA Earth
A research team discovers thousands of previously unknown underwater volcanoes on the seabed. These can open up a "window to the Earth's mantle" for researchers.
San Diego – The oceans are an important part of the Earth, with 70 percent of the planet covered by oceans. Nevertheless, we know shockingly little about the deep sea and the seabed – just five percent of 300 million square kilometers of seabed have been explored, Deutsche Welle reported. One of the reasons for this is that it is very dark and cold from a depth of about 200 meters, and the pressure is also very high - which makes exploration extremely difficult.
But now a research team from the Scripps Institution of Oceanography at the University of California in San Diego has succeeded in studying part of the seafloor without diving down. The team used data from radar satellites to map volcanoes on the seabed. The study was published in the journal Earth and Space Science. According to the research, only 20 percent of the seabed has been mapped by ships so far.
New study: Thousands of underwater volcanoes exist in the oceans
For their study, the research group discovered 19,325 new underwater volcanoes (they are also called "underwater mountains" in the study), almost doubling the number of known volcanoes in the sea. Previously, 24,643 underwater mountains were known. According to the study, the newly discovered mountains in the sea have a height of between 421 meters and 2,500 meters.
"There are a handful of studies that have predicted that there are thousands of mountains at the bottom of the sea. Even then, 19,000 new seamounts are still incredible," study co-author Julie Gevorgian told Newsweek. The researcher was particularly impressed by the fact that the mountains are so high and that they have remained undiscovered so far.
Study: Underwater volcanoes are a "window on the composition of the Earth's mantle"
Just like volcanoes on land, underwater volcanoes are formed by a collision of tectonic plates or by a volcanic eruption. Knowing where an underwater mountain is located can be important – for example, for submarines on their way in an ocean. The mapping of the mountains also helps researchers to understand the tectonic plates and geomagnetic field of the Earth. "From a geological perspective, seamounts are particularly important because they are windows into the composition and temperature of the Earth's mantle," the research group wrote in the study.
Just like above-ground volcanoes, underwater volcanoes can also erupt. In fact, three-quarters of Earth's volcanic activity takes place underwater, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). As a rule, volcanic eruptions of underwater volcanoes are not as explosive as eruptions of volcanoes on land. This is due, among other things, to the high water pressure – instead of a violent explosion, a passive lava flow is created on the seabed.
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The explosion of an underwater volcano near Tonga sent shock waves around the earth. (Archive image) © imago images/Cover-Images
Eruptions of underwater volcanoes can be dangerous
However, there are exceptions: Some eruptions of underwater volcanoes can be dangerous, because they can trigger tsunamis, for example, if they are close enough to the surface. The eruption of the underwater volcano near Tonga was an example of this. The shock waves after the eruption traveled around the Earth, the explosion had, according to NASA, the explosive power of about ten megatons of TNT – more than 500 times the atomic bomb dropped on Hiroshima. (tab)