A 3D presentation of the subsurface volcano, Hunga Tonga.
https://www.abc.net.au/news/2022-01-22/satellite-data-images-reveal-power-of-tonga-volcano-eruption/100773458Meteoric water and sea water reactions in these volcanoes produce super heated steam which results in rapid and massive volume expansion. In this case, 100m below the surface, the water would have boiled and then expanded rapidly resulting in a massive explosion together with the energy from the magma of the volcano itself.
Hunga Tonga Volcano 2km high almost entirely under the ocean surface.(abc.net.au)Typically, these oceanic crust volcano's on the Rim of Fire are less viscous than their continental counterparts (South America). The oceanic crust lavas are more iron and magnesium rich producing more fluid and flat volcanic flows like what you see in Hawaii.
But with sea water involved, this volcanic event, termed a phreatomagmatic eruption, had the right conditions and depth to let loose.
