Stromboli is an unusual volcano. Located on an island of the same name, just north of Sicily, it has been erupting continuously for at least 2000 years. Tourists flock to Stromboli to climb the mountain and witness the explosions that send clots of lava flying out of the volcano’s vent every 10 to 15 minutes. Figure 1 shows the attraction. (Mount Yasur, halfway around the world in the island nation of Vanuatu, erupts in the same way and draws a similar crowd.) The clots usually land within the volcano’s crater and pose no threat to anyone. But once or twice a year, larger explosions endanger the visitors, their guides, volcanologists, and sometimes the few hundred inhabitants of the island’s two small villages.
Forecasting the larger, more dangerous eruptions more than a few minutes in advance is not currently possible. Little is known about the arrangement of the conduits, or plumbing,...
