Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington
Journal of Volcanology and Geothermal Research
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Abstract
The 2004-2008 eruption of Mount St. Helens (MSH), Washington, was preceded by a swarm of shallow volcano-tectonic earthquakes (VTs) that began on September 23, 2004. We calculated locations and fault-plane solutions (FPS) for shallow VTs recorded during a background period (January 1999 to July 2004) and during the early vent-clearing phase (September 23 to 29, 2004) of the 2004-2008 eruption. FPS show normal and strike-slip faulting during the background period and on September 23; strike-slip and reverse faulting on September 24; and a mixture of strike-slip, reverse, and normal faulting on September 25-29. The orientation of ??1 beneath MSH, as estimated from stress tensor inversions, was found to be sub-horizontal for all periods and oriented NE-SW during the background period, NW-SE on September 24, and NE-SW on September 25-29. We suggest that the ephemeral ~90?? change in ??1 orientation was due to intrusion and inflation of a NE-SW-oriented dike in the shallow crust prior to the eruption onset. ?? 2010 Elsevier B.V.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington |
| Series title | Journal of Volcanology and Geothermal Research |
| DOI | 10.1016/j.jvolgeores.2010.08.015 |
| Volume | 198 |
| Issue | 1-2 |
| Year Published | 2010 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Volcanology and Geothermal Research |
| First page | 129 |
| Last page | 142 |
| Google Analytic Metrics | Metrics page |