Examining crystals formed deep within volcanoes could give a year's
warning of impending eruptions, say scientists from the University of
Bristol.
The researchers used forensic-style chemical analysis to link seismic
observations of the deadly 1980 Mount St Helens eruption to crystal
growth within the magma chamber, the large underground pool of liquid
rock beneath the volcano.
Specifically, the team studied zoned crystals, which grow concentrically
like tree rings within the magma body. Individual zones have subtly
different chemical compositions, which reflect the physical changes
within the magma chamber and can thus indicate what volcanic processes
are going on and the timescales over which they take place.
Peaks in the growth of iron- and magnesium-rich crystals were found to
correlate with increased seismicity and gas emissions in the months
running up to an eruption. In the case of Mount St Helens, the crystals
indicated that pulses of magma were flowing into a growing chamber
within the volcano.
This forensic approach can be applied to other active volcanoes to
improve forecasting of future eruptions.
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