The Mountain Is Rumbling.(Mount Etna)(Brief Article)

Each spring, residents of Catania walk the Sicilian's town's narrow streets chanting prayers and touting relics of Saint Agatha, their patron saint and protectress against an eruption of Mount Etna. All the while, the mountain looms overhead, belching smoke, ash and lava. Although villagers have gotten used to these displays of defiance, this year they have reason to pray with more than the usual fervor. In the past few weeks, seismologists have logged hundreds of earthquakes near the mountain's summit. Each quake is far too weak to mean much to the hundreds of villages on Etna's slopes and foothills. But taken together, they suggest that Europe's most active volcano is about to deliver a whopper.

The prospect of Etna's blowing its stack has got scientists in a tizzy. The last big eruption, back in 1669, lasted four months, sent a kilometer-wide river of lava down the mountain and killed 20,000 people. At the very least, an eruption of similar force would cause billions of dollars in damage to the crops, the environment and tourism. Skiers ply the slopes in winter. In summer visitors come to enjoy the unusual scenery: a cable car takes them past hardened lava flows that encase tree trunks, old poles from collapsed funicular lines and even the odd truck chassis. The visitors' center at 7,875 feet stands next to charred skeletons of previous structures--a caution to anybody preparing to make the journey up the summit. Plenty do, and occasionally some get killed by falling lava or hot blasts of volcanic gas. Tourists and scientific research teams make up well over half of the area's income. The rest comes from agriculture. The nutrient-rich soil, fed from minerals in the volcanic acid rains, produces award- winning wines, such as Nerello Mantellato. Curiously large lemons and bumper crops of olives entice farmers to stay in spite of the obvious dangers. About 1 million Sicilians, or 20 percent of the island's population, live in Mount Etna's shadow.

The only insurance against loss of life is scientists' ability to sound the alarm early enough to evacuate residents. Trouble is, when it comes to erupting volcanoes, scientists are a trifle insecure about their predictive powers. At present, a few weeks of warning is about all anybody can hope for. "We're probably OK for the next 15 days," says Danilo Reitano, one of a handful of engineers and geologists who are keeping a 24-hour vigil on the mountain, "but I'm not going to make any guesses beyond that." The imminent eruption has given Reitano and his colleagues at the Uni-fied Center for the Acquisition of Data a bit of performance anxi-ety. "How well we monitor activity on Etna is a valuable source of information for scientists all over the world," he says, "and so are our failures." If scientists knew better the telltale signs of a big eruption, they would feel more confident. Ironically, a big eruption of

Mount Etna is their best chance yet of learning what these signs are.

Etna has long been a closely watched volcano, partly because it is one of the world's most complex and interesting. Located on the eastern side of Sicily, it is one in a chain, including Mount Vesuvius and Marsili, a vast underwater mountain, that formed when Africa collided with Europe a couple of hundred million years ago. Active since at least the ...