This is an image of a pyroclastic flow going down the slopes of a volcano to the sea.
Click on image for full size
Image from: U.S. Geological Survey, photo by B. Yount
Mt. Pelee
Mt. Pelee is not a very tall volcano, in fact it is an example of what is called a "lava dome".
An extremely destructive
eruption of Mount Pelee occurred in 1902. The
coastal town of St. Pierre, about 4 miles downslope to the south,
was
demolished and nearly 30,000 inhabitants were killed almost instantly by a pyroclastic flow which swept down the mountain. Such a flow is illustrated in this picture of an Alaskan volcano.
The cloud of hot ash and gases swept into town at an estimated speed of 100 miles per hour or more. It would only have been 5 minutes for the pyroclastic flow to sweep from the volcano's summit into town.
Survivors of this eruption included one man who was in an underground jail cell, as well as sailors who were off-shore and witnessed the destruction of the city from a distance. Comments by these eyewitnesses included the following:
- "The mountain was blown to pieces, there was no warning."
- "It was like a giant oil refinery."
- "There was hurled straight toward us a solid wall of flame. It sounded like a thousand cannon."
- "The wave of fire was on us and over us like a flash of lightning. It was like a hurricane of fire."
- "The town vanished before our eyes."
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