Q&A: Geology Department’s Lynne Elkins on Volcanoes

Posted March 25th, 2009 at 11:13 am.

elkinsAlaska’s Mt. Redoubt has started to send plumes of ash and steam thousands of feet into the air. And if the volcano stays true to its past history, it could cause havoc for area residents for some time, affect the local oil industry, and disrupt flight paths.

We asked geologist Lynne Elkins, whose research focuses on volcanoes and volcanic activity, to give us a crash course in volcanoes.

What is a volcano?

A volcano is a location where magma (molten rock) from depth extrudes onto the earth’s surface. Materials emitted by volcanoes include lava, volcanic ash, and hot gases and other volatile materials.

What causes a volcano to erupt?

A number of things can cause eruptions. Magma generally pools beneath the volcano in a magma chamber, and injection of new magma from depth into the chamber can cause an increase in pressure that might lead to eruption. If magma starts to rise, dissolved gases can also begin to exsolve and expand, creating potentially explosive conditions. Interaction between hot magma and groundwater can cause the water to flash to steam, precipitating explosions.

Are there any active volcanoes in this area? What about the rest of the United States?

There are not active volcanoes in this area, but there are many in the United States as a whole. A lot of attention is being paid to Mt. Redoubt in Alaska right now, and there are quite a few other dangerous volcanoes in Alaska. Hawaii is also home to several active volcanoes. The Cascade Mountain Range in the Northwest contains volcanoes that include Mt. St. Helens, which is famous for its eruptions in the 1980s and has had renewed activity in the last few years. There are also less frequently active volcanoes in the Southwest, in New Mexico and Colorado.

Is there any particular volcano researchers really have their eye on—one that’s active and near a populated area?

Obviously Mt. Redoubt is being monitored closely. It is upwind of Anchorage and near an oil terminal. Volcanoes in Hawaii have been continuously active for years, though large numbers of people are a little farther away from the most dangerous areas there. The Cascades volcanoes are also closely monitored, because they are near large population centers (Mt. Rainier, for example, is close to Seattle).

What sort of damage occurs when a volcano erupts? Are some eruptions worse than others? Are researchers able to predict accurately how bad a particular eruption will be?

There can be a few different kinds of damage. Lava flows can destroy property, but generally move slowly enough that people can safely escape. Ash can cause respiratory problems if inhaled, can accumulate on buildings and cause property damage, and is very dangerous for aircraft. If loose ash mixes with rainwater, the volcanic mudflows that can form can be dangerous to both people and property. Some volcanic gases are dangerous to breathe, as well. And explosive and pyroclastic behavior (hot ash clouds or density flows) can both destroy property and kill and injure people. Most eruptions have only some of these hazards, so there are certainly more and less dangerous eruptions. Scientists study the past history of a volcano to help determine what kind of hazards are likely to occur, and where they will happen, and that helps people to be informed.

Tell us about your research interests.

I study the geochemistry of volcanic materials. I have done some work on volcanic and geothermal gas chemistry, which relates to hazardschanges in the chemistry of gases released by volcanoes can signal changes in behavior deeper in the volcanic system. Most of my work, however, focuses on what the chemistry of lava and gas can tell us about how the Earth works as a whole. I seek to answer questions such as “Where does melting first occur beneath a volcano?” “What is melting in the first place, and how much?” “How rapidly does the magma rise?” I use a range of chemical and isotopic geochemistry tools to try to get at the answers to those questions.

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