THE SITUATION: For some reason, you find yourself within striking distance of an active volcano. Then, it erupts. It’s coming, and it’s coming fast—too fast for you to outrun the flow. Luckily, you’re not completely doomed.
WHAT DO YOU DO? Before making your escape, you need to figure out what find of flow you’re dealing with, says Greg Valentine, a geology professor at the University of Buffalo.
“The first one is a lava flow. What you see in video of Hawaii with these rivers of lava flowing down the volcano," says Valentine. "Your best bet is to go uphill or climb some structure that’s above the flow. The lava’s gonna stay in the low ground.”
For the other kind—pyroclastic flow, a mixture of hot gases and particles that travels at about a hundred yards per second and can reach hundreds of degrees in temperature—you'll want to do the exact opposite. "With these, your best bet is to go underground, into a basement," Valentine says. "There was a famous eruption on the island of Martinique very early in the 20th century, where a whole city was destroyed. Everyone died except for a few people, one of whom was a prisoner in a dungeon."
So why high ground for lava and below ground for pyroclastic?
“[Pyroclastic flows] move at a very high speed and are often hundreds of feet high, so when it hits you, it can be greater than hurricane-force winds. They're full of debris, rocks, and pieces of buildings, too," says Valentine. "You want to be underground somewhere that’s like a bomb shelter, protected from the heat, protected from the force of the flow. If you were underground in a basement and a lava flow went over you, you’d be safe, I guess, but you wouldn’t be able to get out. When a lava flow cools it makes solid rock, so you’d be trapped.”