May 26, 2012
Crystal Composition Could Predict Volcanic Eruptions
By studying crystals formed in volcanic rock, experts may be able to predict an impending eruption up to a year in advance, researchers from the University of Bristol have discovered.
According to a Thursday press release from the university, Dr. Kate Saunders and her colleagues used forensic-style chemical analysis to link seismic observations of a 1980 eruption at Mount St. Helens to the growth of crystals within the large underground pool of liquid rock beneath the volcano known as the magma chamber.
Writing in the journal Science, Dr. Saunders and her associates describe how they analyzed zoned crystals, which grow concentrically (similar to tree rings) within the magma body. Different areas have subtle differences in their chemical compositions, which reflect changes in physical conditions within the chamber and serve as a possible indicator over the volcanic processes and the time frames during which they occur.
"Chemical analysis of the crystals revealed evidence of pulses of magma into a growing chamber within the volcano. Peaks in crystal growth were found to correlate with increased seismicity and gas emissions in the months prior to the eruption," the Bristol University statement said. "This forensic approach can be applied to other active volcanoes to shed new light upon the nature and timescale of pre-eruptive activity. This will help scientists to evaluate monitoring signals at restless volcanoes and improve forecasting of future eruptions."
Charles Q. Choi of OurAmazingPlanet explained that the researchers studied orthopyroxene crystals within rocks taken from nine different eruptions at the Washington volcano between 1980 and 1986.
They discovered that the rims of those crystals typically grew within the year leading up to each eruption, and TGDaily writer Kate Taylor noted that they found a correlation between the growth of crystals that were rich in iron and magnesium and increases in seismicity and gas emissions in the months preceding an eruption.
"Volcanoes tend to erupt in a similar cycle and have similar trends," Saunders told Elizabeth Lopatto of Bloomberg News during a telephone interview on Thursday. "If we can work out their behavior, it allows us to know what to look for. We can better evaluate the monitoring signals."
However, she added, they had "no predictions on what might erupt soon," adding that her team planned to explore how they can link the composition of those crystals to other monitoring techniques in order to better understand volcanoes. Saunders told Bloomberg that they provide scientists with a record of a volcano's activity, and that the more they learn about the crystals, "the better we can predict eruptions."