geology

Why volcanos do what they do

PENN STATE (US) — Ongoing observations of the Soufriere Hills Volcano on Montserrat since it erupted in 1995 are expected to advance understanding of the workings of andesite volcanos.

“To the extent that the Soufriere Hills Volcano is typical of andesitic dome building volcanoes, results from this research can be expected to apply more generally,” says Barry Voight, professor emeritus of geosciences at Penn State.

Voight and R. S. J. Sparks, professor of geology at Bristol University, guest edited and introduced a special issue of Geophysical Research Letters that covers the past ten years of research in the CALIPSO (Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory) and SEA-CALIPSO (Seismic Experiment with Airgun) projects.

CALIPSO is a volcano monitoring system installed in late 2002 and early 2003 to monitor magma activity of the volcano. It consists of an array of specialized instruments located in four strategically placed, 650-foot-deep bore holes along with surface and shallow-hole instrumentation.

Researchers looked at surface deformation, magma activity, explosive dynamics of the volcano, and the magma system.

The papers cover four different explosive episodes and volcano mechanics.

calipso_2

Researchers believe study of the volcano will advance understanding of how crust evolves in arc systems, magma is stored and transported, and how volcanic processes proceed. (Credit: Barry Voight)

SEA-CALIPSO obtained three-dimensional images of the structure of the island of Montserrat and of the volcano’s center.

It was an active-source seismic experiment to study the Earth’s crust beneath the island and the volcano and was under the umbrella of the CALIPSO project.

“This multinational experiment with participation from the US, UK, New Zealand, Trinidad, and Montserrat generated high resolution images of the island, its volcanic edifices, and adjacent crust,” says Voight.

“This project should advance our understanding of how crust evolves in arc systems, magma is stored and transported and how volcanic processes proceed.”

SEA-CALIPSO used seismic tomography, seismic reflection/refraction imaging, and offshore seismic profiling to view the deep structure of the volcano.

Evaluation of the speed at which seismic waves pass beneath and through the island can provide information on the structure of the crust and the magma chambers beneath the volcano.

The research was supported by the US National Science Foundation, UK Natural Environmental Research Council, British Geological Survey, and the Discovery Channel.

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