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Once volcanoes begin to erupt, nobody can stop them.
But by studying volcanoes, people can limit the damage they do. Information about a volcano’s past eruptions helps scientists predict how the volcano may behave in the future. Volcanologists, scientists who study volcanoes, examine old lava flows, ash layers, and other evidence. They figure out a history of eruptions through millions of years.
Volcanologists also study the day-to-day life of volcanoes to find warning signs of coming eruptions. Some signs, like increased ash or fumes from the crater, are easy to see. Others, like minor earthquakes, are so small that only scientific instruments can detect them. Volcano-watching techniques are far from perfect, but they are improving—and they’re better than guessing.
▲ After a five-hour climb, a volcano observer uses a temperature probe to measure the heat of escaping gases on Indonesia’s Mount Merapi. A staff of observers keeps track of Indonesia’s 130 active volcanoes.
◀ Geologists use a theodolite (thee-ODD-uh-lite), which is a surveying telescope. It provides information on changes in a volcano's crater that can help them predict an eruption.
▲ Dante the robot looks like a spider, with eight legs and six eyes. It was built to crawl into Mount Erebus, a volcano in Antarctica, to study lava and gases.
◀ By monitoring small earthquakes, scientists accurately forecast a 1975 eruption in Russia. Predictions for the Tolbachik volcano were so precise that TV cameras were there for the event.
▲ Protected by a fire-resistant suit, a scientist samples lava from an active volcano. Monitoring changes in the lava’s chemistry gives scientists clues about how the volcano works.
▲ Monitoring active volcanoes can be dangerous work. Volcanologist David A. Johnston was killed during the 1980 eruption of Mount St. Helens while he was studying the volcano. Although an eruption was likely, no one could pinpoint its time or size.
◀ A Hawaiian woman makes an offering to Pele, the goddess of volcanoes. According to Hawaiian folklore, when Pele is angry, she unleashes waves of lava from the underworld. We now have scientific explanations for volcanoes. However, Pele remains an important part of Hawaiian folk tradition.
▲ In Japan, communities in the path of active volcanoes conduct routine evacuation drills. They know that scientific prediction alone cannot save people from a disaster.
◀ Thomas A. Jaggar pioneered the idea of permanent laboratories on the slopes of volcanoes. The observatory he founded on Hawaii in 1912 is now one of dozens around the world.
Check It Out!
Every year, about 50 volcanoes erupt on land or in shallow water where we can see them. But how many volcanoes have the potential to erupt?
There is no precise answer, because each volcano has a unique history. For some, the time between eruptions may be days, while for others it may be hundreds or even thousands of years.
