A lahar, which is essentially a mudflow filled with rock particles, can reach speeds as high as 120 miles per hour.
Kīlauea has been particularly active over the past few weeks.
The U.S. Geological Survey issued its highest-level warning nearly two weeks after the volcano first began erupting.
The volcanic region the produced Olympus Mons may also have been responsible for keeping Mars wet.
A medieval poem, tree rings and ice cores have revealed new information on the history of Christianity in Iceland.
Scientists have never been able to separate the sound of thunder from the rest of an eruption's clatter.
Volcano in Indonesia continues to erupt after laying dormant for hundreds of years.
The active volcano, whose alert level is at its highest, erupted four consecutive times on Tuesday morning.
The crystals carry a memory of environmental changes the way trees do with their rings.
Mount Mayon's gigantic explosion sent superheated lava and molten rocks crashing onto nearby villages.
"We know virtually nothing about submarine volcanoes."
The volcano has the potential to turn deadly.
The eruption lasted over eight minutes.
The global events happen way more often than scientists thought.
The magma under a long-ago supervolcano never heated up as thoroughly as scientists had assumed.
There's no way to know how many eruptions are in the cards.
The U.S. is advising against any visits to the volcano, warning that an eruption could disrupt flights.