Beneath the waves of the Pacific Ocean, about 470 kilometers off the coast of Oregon, lies Axial Seamount, an undersea volcano at the cutting edge of scientific exploration. Decades of monitoring have ...

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.