Shelf Life 18: Under the Volcanoes

“If we connect compositions and combinations [of pressure and temperature] to what happens inside the Earth, that might be able to help predict eruptions.”

Shuo Ding, Kalbfleisch Postdoctoral Fellow, Department of Earth and Planetary Sciences

Researchers are trying to uncover the secret “ingredients” behind dangerous eruptions. Expeditions to Mt. Vesuvius—one of the world’s best-known volcanoes—and Alaska’s Mt. Saint Augustine provide specimens that can be compared to materials synthesized in the lab. Understanding what makes one volcano’s magma so much more explosive than another may one day help us avoid volcanic disasters. 

Two volcanoes loom large in Jim Webster’s research. Webster, the Museum’s curator of mineral deposits, studies both Mount Vesuvius, Italy—the site of one of the world’s most famous eruptions—and the lesser-known Mount Saint Augustine in Alaska. In 2006, only a few months after an eruption of Augustine, he flew with a small team of geologists to this remote volcanic island in the Aleutian chain. Every morning, they would load into a helicopter and be dropped off at a location on the volcano’s slopes. They’d work their way down, collecting samples along the way. “Hot rocks would occasionally come tumbling down the side of the volcano,” says Webster.

Two people, one in a gas mask and the other facing away, climb on a dark rocky mountain as smoke blows behind them. Charlie Mandeville, a research associate of the Museum, and Kate Bull of the USGS / Alaska Volcano Observatory collect samples on the still-smoking slopes of Alaska’s Mount Augustine volcano in 2006.
J. Webster/© AMNH
Man stands next to two enormous rocks, a volcanic boulder which has fallen and split in two. Curator Jim Webster stands next to a large volcanic boulder that rolled down the slope of Augustine, and broke open.  
J. Webster/© AMNH

Webster brought some of those rocks back to New York, where he compares them to samples collected at Vesuvius and to artificial materials he synthesizes in his experimental petrology lab. Mt. Saint Augustine and Mt. Vesuvius have several things in common: they’re both young in geologic terms—less than 200,000 years old; they both have magmas rich in volatiles like water, carbon dioxide, sulfur, and chlorine; and both erupt gases that are highly charged with carbon dioxide and water. But, the two volcanoes have very different eruptive cycles. Webster and Kalbfleisch Postdoctoral Fellow Shuo Ding are re-creating pre-eruptive conditions inside the lab and comparing their results to the natural volcanic samples in the hopes that one day we may understand how the different “ingredients” in magma can make one volcano more explosive than another.