Magma (or lava when erupted at the surface) is composed of molten liquid rock and solid crystals. These crystals are often chemically zoned and preserve a record of processes occurring beneath the volcano prior to eruption. The width of these zones varies from millimetres to a few hundred nanometres and contains important chemical information. The crystal zones can be treated in a similar manner as tree rings, which record the growth history of a tree. Instead of counting the number of zones to determine the age of a crystal, scientists use the diffusive relaxation of chemical elements between adjacent zones to retrieve timescales of pre-eruptive processes from days to decades. The exceptionally high spatial resolution of the FEG-EPMA will allow Professor Blundy and his team to access even shorter timescales than were previously possible.
The ultimate objective of the research supported through CRITMAG is a better understanding of the processes by which magma is transported from the deep crust through the sub-volcanic plumbing system and eventually to the surface, and of the timescales on which transport occurs. Moving magma beneath the surface triggers a host of ancillary signals, such as earthquakes and ground deformation that can be detected by monitoring equipment. By using the new FEG-EPMA to unravel timescales commensurate with the monitoring of signals at active volcanoes, scientists will be able to better understand the significance of pre-eruptive changes to the monitoring signals and so improve the ability to forecast volcanic eruptions.
Provided by University of Bristol
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