Pyroclastic flows are the result of explosive eruptions of molten or solid rock fragments, or both. The rocks and gases inside a pyroclastic flow can range from 392 to 1,292 degrees Fahrenheit, meaning they destroy everything in their path, causing wood, vegetation and houses to burst into flame. At night, from a safe distance, glowing pyroclastic flows can be seen careening down the slopes of the Soufriere Hills volcano like tumbling fire. Volcanologists monitoring the Montserrat volcano, one of seven on the island, were startled to discover a new type of flow, one that is potentially more lethal, borne from such surges. It flowed like a river to a much greater distance than the surge would have done.
Higher rates mean explosions are more likely.
The Montserrat volcano is only one of many being studied by scientists. The Smithsonian Institution's Global Volcanism Program gives preliminary reports of dangerous volcanoes, and a Web site called Volcano World tracks 92 of the world's active volcanoes, including the legendary Indonesian volcano Krakatoa, which exploded in earthquakes last spring. The goal, of course, is to better understand volcanoes so scientists can more accurately predict dangerous activity and avoid catastrophes like the 1902 eruption of Martinique's Mount Pelee, another Caribbean stratovolcano. That volcano awakened scientists to the existence of pyroclastic flows and started a line of research that is still continuing. The eruption killed 29,000 people, the most casualties from any volcano this century.