| 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. |
| Genre: | Article |
| ProdID: | 70037619 |
| Citation Author: | Lehto, H. L.; Roman, D. C.; Moran, S. C. |
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| Citation End Page: | 142 |
| Citation Issue: | 1-2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Volcanology and Geothermal Research |
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| Citation Number Of Pages: | 14 |
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| Citation Search Results Text: | Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington; 2010; Article; Journal; Journal of Volcanology and Geothermal Research; Lehto, H. L.; Roman, D. C.; Moran, S. C. |
| Citation Start Page: | 129 |
| Citation Volume: | 198 |
| Citation Year: | 2010 |
| Type: | citation/reference |
| Text: | Temporal changes in stress preceding the 2004-2008 eruption of Mount St. Helens, Washington; 2010; Article; Journal; Journal of Volcanology and Geothermal Research; Lehto, H. L.; Roman, D. C.; Moran, S. C. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1016/j.jvolgeores.2010.08.015 |
| Date Other: | Fri, 1 Jan 2010 00:00 -0600 |
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