Volcanic gas used to measure ‘explosivity’

Josh Hartman - Lopez.jpg

Alaska is pockmarked with 52 historically active volcanoes—around half of which consistently release gas. Scientists study this gas to forecast eruptions and to understand the “plumbing systems of Alaska’s volcanoes,” according to the abstract of Taryn Lopez’s lecture.

Lopez, a researcher and assistant professor, studies the flow and make-up of volcanic gas.

To understand a volcano the two main gases to look at are carbon dioxide and sulfur dioxide, the second and third most abundant volcanic gases respectively. These two gases are dissolved in the volcano in hot, liquid rock called magma.

If the magma starts to move up toward the surface, some of those gases get released into the air.

“It’s just like if you open a can of soda and the bubbles come up,” Lopez said.

When that magma starts to come up, carbon dioxide is released before sulfur dioxide. If scientists see that there is a lot of sulfur compared to carbon in the gas, that would mean that there is magma getting close to the surface—which could indicate an eruption, according to Lopez.

The other indicator of an eruption is how much sulfur dioxide is being released from the volcano. Usually, more than 1,000 tons per day of sulfur flowing out of the volcano indicates that an eruption will happen, Lopez said.

An explosive eruption occurs when something blocks the gases from escaping and they build up inside the volcano increasing the pressure until it blows. This phenomena has been observed at several Alaskan volcanoes, according to Lopez.

Lopez will explain how to measure volcanic gas and how that data is used in a Science For Alaska lecture on Tuesday, Feb. 14 at 7 p.m. in the Raven Landing Center, 1222 Cowles Street.

The lecture series will continue at 7 p.m. every Tuesday until March 7 at that location.

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