Volcanoes that are located in the interior of continents, such as Yellowstone, are especially dangerous because of the thick granitic magma involved. The thicker magma acts like a plug and traps explosive gases. Hawaii-like volcanoes, on the other hand, generally consists of highly fluid magma which gently flows out of the volcano. Volcanoes like Mt. St Helen are somewhere in between because they are on or near the boarder of a continent and ocean (basaltic magma/lava vs granitic magma/lava). Continents are basically granitic, Oceans basaltic, in composition.
I was wondering about that. I didn’t know if the rock underneath was liquidy or not.
thx.