期刊
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
卷 153, 期 1-2, 页码 37-50出版社
ELSEVIER
DOI: 10.1016/j.jvolgeores.2005.08.008
关键词
seismic trigger; low-frequency events; conduit resonance; Soufriere Hills; Montserrat
资金
- Natural Environment Research Council [NER/A/S/2003/00512] Funding Source: researchfish
A careful analysis of low-frequency seismic events on Soufriere Hills volcano, Montserrat, points to a source mechanism that is non-destructive, repetitive, and has a stationary source location. By combining these seismological clues with new field evidence and numerical magma flow modelling, we propose a seismic trigger model which is based on brittle failure of magma in the glass transition. Loss of heat and gas from the magma results in a strong viscosity gradient across a dyke or conduit. This leads to a buildup of shear stress near the conduit wall where magma can rupture in a brittle manner, as field evidence from a rhyolitic dyke demonstrates. This brittle failure provides seismic energy, the majority of which is trapped in the conduit or dyke forming the low-frequency coda of the observed seismic signal. The trigger source location marks the transition from ductile conduit flow to friction-controlled magma ascent. As the trigger mechanism is governed by the depth-dependent magma parameters, the source location remains fixed at a depth where the conditions allow brittle failure. This is reflected in the fixed seismic source locations. (c) 2005 Elsevier B.V. All rights reserved.
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