A new study explains why even gas-rich, supposedly explosive volcanoes sometimes erupt quietly instead of blowing apart.

To residents of a certain age, it almost seems like it was yesterday. But Sunday, remarkably, marks the 45th anniversary of a cataclysmic explosion on Mount St. Helens. In a matter of seconds on the ...

In this May 18, 1980, file photo, Mount St. Helens sends a plume of ash, smoke and debris skyward as it erupts. On that day, the Mount St. Helens volcano in Washington state exploded, leaving 57 ...

Mount St. Helens looked like it might be erupting again. Commercial pilots flying in the area Tuesday reported clouds of fine volcanic ash rising into the air above the collapsed dome of the Cascades’ ...

Saturday marks the 44-year anniversary of Mount St. Helens' eruption in Washington. The blast on May 18, 1980, is the worst volcanic eruption in U.S. history, killing 57 people and spewing 520 million ...

On May 18, 1980- The most powerful volcanic eruption in U.S. history occurred. On May 18, 1980- The most powerful volcanic eruption in U.S. history occurred. Located in Washington State, Mount St.

Scientists have discovered that shear forces inside rising magma can create gas bubbles long before pressure drops occur. The ...

The explosiveness of a volcanic eruption depends on how many gas bubbles form in the magma—and when. Until now, it was ...

Mount St Helens, Washington viewed from Portland, Oregon. Source: Ilan Kelman The volcano Mount St. Helens in Washington state exploded at 8:32 a.m. on May 18th, 1980, exactly 40 years ago.