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March 29, 2004 Comparing SO2 emissions with Long Period Seismicity at
Soufriere Hills Volcano, Montserrat |
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Volcanic sulfur dioxide (SO2) measurements of passive plumes have recently improved with the application of Differential Optical Absorption Spectroscopy (DOAS). In January 2002, the Montserrat Volcano Observatory intalled two fixed DOAS instruments which collect rapid, continuous measurements of SO2 emissions. For the first time, SO2 fluxes are being collected on a time scale of minutes, allowing short-term changes to be evaluated with respect to atmospheric transport, surface activity, and magmatic source mechanisms.
In this study, we investigate relationships between SO2 emissions and long period (LP) seismicity on Montserrat. At Montserrat and many other volcanoes, LPs have often preceded eruptions, dome collapses and increased pyroclastic flow activity. LPs have also been associated with dome inflation/deflation cycles, suggesting a link to internal processes involving pressurization and magma degassing. Modeling of LPs indicate the source to be a resonating fluid within an elastic medium. Observed waveforms are a function of many factors including conduit geometry, the density contrast between the fluid magma and surrounding rock, and the magmatic gas content.
This presentation will include: 1) an overview of long period seismicity, 2) a description of DOAS and it's unique implementation on Montserrat, 3) initial results of comparing SO2 emissions to long period seismicity, and 4) the challenges associated with comparing these two independent datasets.