Volcano Survivor 3: Mount Unzen, Japan, 1991.November 7, 2014
One of the greatest dangers in a volcano eruption is not the lava flow, being hit by a lump of flying lava or rock, but by being choked by the fast moving scorching hot pyroclastic cloud.
In 1991 pyroclastic cloud blew out of the side of Mount Unzen in Japan. NASA has an excellent diagrams for such an event here.
According to the NASA website:
Highly mobile, these flows reach velocities of up to 400 kilometers (250 miles) per hour and can spread as far as 100 kilometers (60 miles) from the eruption point.
Can you out run a pyroclastic cloud?
Here is what happened in 1991 when the pyroclastic cloud blew out of the side of Mount Unzen in Japan.