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Patterns of volcanotectonic seismicity and stress during the ongoing eruption of the Soufrie??re Hills Volcano, Montserrat (1995-2007)

Journal of Volcanology and Geothermal Research

By:
, , ,
DOI: 10.1016/j.jvolgeores.2008.01.014

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Abstract

The ongoing eruption of the Soufrie??re Hills Volcano, Montserrat, has been accompanied throughout by varying levels of high-frequency, 'volcanotectonic' (VT), seismicity. These earthquakes reflect the brittle response of the host rock to stresses generated within the magmatic system and thus reveal interesting and useful information about the structure of the volcanic conduit system and processes occurring within it. In general, systematic changes in the rate, location, and fault-plane solutions of VT earthquakes correspond to changes in the volcano's behavior, and indicate that the main conduit for the eruption is a dike or system of dikes trending NE-SW and centered beneath the eruptive vent. To date, the eruption has comprised three extrusive phases, separated by two ~ 1-2??year-long periods of residual activity. Prior to the start of each extrusive phase, VT earthquakes with fault-plane solution p-axes oriented perpendicular to inferred regional maximum compression dominate the data set, consistent with stresses induced by the inflation of the mid-level conduit system. ~ 90??-rotated VT fault-plane solutions are also observed preceding a change in eruption style from effusive to explosive in 1997. While increases in the rate of VT earthquakes precede eruption phase onsets, high rates of VT seismicity are also observed during the first period of residual activity and in this case appear to reflect the relaxation of host rock following withdrawal of magma from the mid-crustal system. Most VT earthquakes are located directly beneath the eruptive vent, although two 'distal VT clusters' were observed during the first six months of the eruption (late 1995-early 1996). Both of these distal clusters likely resulted from stresses generated during the establishment of the main conduit system. ?? 2008 Elsevier B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Patterns of volcanotectonic seismicity and stress during the ongoing eruption of the Soufrie??re Hills Volcano, Montserrat (1995-2007)
Series title:
Journal of Volcanology and Geothermal Research
DOI:
10.1016/j.jvolgeores.2008.01.014
Volume
173
Issue:
3-4
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
230
Last page:
244
Number of Pages:
15