Most volcanoes form at the boundaries of Earth's tectonic plates, which are huge slabs of crust and upper mantle that fit together like puzzle pieces. Think of these plates as massive rafts floating ...

Forbes contributors publish independent expert analyses and insights. David Bressan is a geologist who covers curiosities about Earth. How and if a volcano explodes depends on how and when bubbles of ...

One of the most explosive volcanoes in U.S. history began its eruption with a trickle, not a blast. Mount St. Helens' gas-laden magma oozed into the cone before the mountain finally erupted in 1980.

The explosiveness of a volcanic eruption depends on how many gas bubbles form in the magma – and when. Until now, it was thought that gas bubbles were formed primarily when the ambient pressure ...