In a fiery phenomenon, which we associate most often with magmatic mountain peaks, it is easy to forget that about 70 percent of all Earth volcanism takes place under ocean waves.
This statistic is a problem for scientists who want to learn more about underwater volcanoes, which are difficult to study due to their submarine environment.
However, new research shows a clever solution – and reveals an incredible side effect of intense magma eruptions on the ocean floor.
In a recent study, a team led by geophysicist John Lyons from the Alaska Volcano Observatory of the US Geological Survey analyzed recordings of low-frequency sound in the atmosphere (called infrasound) from over 70 explosive outbreaks between 201
Bogoslof is rarely seen during outbreaks due to its remote location, but historical accounts tell vivid stories of what it looks like when a submerged volcano is released.
An eyewitness account observed by the steamer Albatross in 1908 describes a "colossal soap bubble" rising from the sea cean, with "gigantic smoke and vapor clouds", while another from one "gigantic dome-like swelling" of the water that is as big as the dome of the capital of Washington … like a huge bubble pushing through the water. "19659003] Thanks to Lyon and his team, we now have a scientific explanation for These mysterious historical descriptions of Bogosloff's colossal domed gas bubble explosion. (Lyons et al., Nature Geoscience, 2019)
Analyzing the infrasound records of Bogoslof's eruptions 2016-2017 – sound waves whose frequency is lower than those of human ears – the researchers developed a model for the likely source mechanism of the deep rumbling of the volcano.  "The infrasound is caused by the vibration and bursting of magmatic gas bubbles, which were originally formed from submerged openings, but grew above sea level and burst," the authors explain in their work.
"We model the low-frequency signals as overpressure gas bubbles that grow near the water-air interface and require bubble radii of 50 to 220 meters." harmful gaseous volcanic bubbles could spread up to 440 meters in diameter.
That would bring them to about the height of the Petronas Towers of Malaysia (the tallest buildings in the world by 2004) and produce an immense bubble volume that could easily swallow several of Giza's great pyramids.
The spectacle rising ominously out of the ocean is not yet over.
"Imagine the violence of a normal volcanic eruption, but then add some more water to it," Lyons said Wired .
Pretty crazy stuff that complements the list of really weird geophysical byproducts we already know when it comes to volcanic eruptions under water from vast areas of volcanic glass, to floating pumice rafts as well as fleeting pop-up islands and the fast ecosystems that they seem to allow.
The results are described in Nature Geoscience .