HR: 11:50h
AN: V22A-07    [Abstracts]
TI: Geophysical Investigations of Soufriere Volcano Crater, St Vincent, West Indies: Where is the Lake?
AU: Moreau-Fournier, M
EM: moreaumagali@yahoo.fr
AF: Dept of Chemical Engineering, The University of the West Indies, St Augustine Campus, St Augustine, Trinidad and Tobago
AU: * Fournier, N
EM: nicofournier@uwiseismic.com
AF: Seismic Research Unit The University of the West Indies, Gordon Street, St Augustine, Trinidad and Tobago
AU: Robertson, R
EM: richie_robertson@uwiseismic.com
AF: Seismic Research Unit The University of the West Indies, Gordon Street, St Augustine, Trinidad and Tobago
AB: Soufriere volcano in St Vincent, West Indies, is one of the most active volcanoes of the Eastern Caribbean arc with eruptions in 1812, 1902, 1971-72 and the latest in 1979. Typical eruption style involved dome building phases alternated with more explosive events such as 1902 when over than 1500 people perished due to pyroclastic flows. Between eruptions, the active crater has always been filled by a deep water lake and this lake, although disappearing during the eruptions, always replenished afterwards within a few years. However, since the last eruption in 1979, the crater remained dry. This work addresses the following questions: Is there any trapped water underground below the crater floor? How much? What is the implication of the presence or not of water in terms of future eruptions dynamics and associated volcanic hazards? We present here the results from a recent resistivity survey on the crater floor, around the degassing dome. Data inversion on several 2D profiles shows a shallow groundwater body below the surface and allows estimate of the volume of water trapped in near surface. The estimated amount of water currently trapped in near-surface is much smaller than it has been since historical times. These results thus raise issues about potential for increased explosivity and associated volcanic hazards when Soufriere volcano will next erupt since water vs. magma mass ratio may be much less than it has been for the past hundreds of years.
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly