The 2004–2008 dome-building eruption at Mount St. Helens, Washington: Epilogue
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Abstract
The 2004–2008 dome-building eruption at Mount St. Helens ended during winter 2007–2008 at a time when field observations were hampered by persistent bad weather. As a result, recognizing the end of the eruption was challenging—but important for scientists trying to understand how and why long-lived eruptions end and for public officials and land managers responsible for hazards mitigation and access restrictions. In hindsight, the end of the eruption was presaged by a slight increase in seismicity in December 2007 that culminated on January 12–13, 2008, with a burst of more than 500 events, most of which occurred in association with several tremor-like signals and a spasmodic burst of long-period earthquakes. At about the same time, a series of regular, localized, small-amplitude tilt events—thousands of which had been recorded during earlier phases of the eruption—came to an end. Thereafter, seismicity declined to 10–20 events per day until January 27–28, when a spasmodic burst of about 50 volcano-tectonic earthquakes occurred over a span of 3 h. This was followed by a brief return of repetitive “drumbeat” earthquakes that characterized much of the eruption. By January 31, however, seismicity had declined to 1–2 earthquakes per day, a rate similar to pre-eruption levels. We attribute the tilt and seismic observations to convulsive stagnation of a semisolid magma plug in the upper part of the conduit. The upward movement of the plug ceased when the excess driving pressure, which had gradually decreased throughout the eruption as a result of reservoir deflation and increasing overburden from the growing dome, was overcome by increasing friction as a result of cooling and crystallization of the plug.
Study Area
Publication type | Article |
---|---|
Publication Subtype | Journal Article |
Title | The 2004–2008 dome-building eruption at Mount St. Helens, Washington: Epilogue |
Series title | Bulletin of Volcanology |
DOI | 10.1007/s00445-015-0973-4 |
Volume | 77 |
Issue | 10 |
Year Published | 2015 |
Language | English |
Publisher | Springer International |
Publisher location | Berlin, Germany |
Contributing office(s) | Volcano Science Center |
Description | Article 89, 17 p. |
Country | United States |
State | Washington |
Other Geospatial | Mount St. Helens |
Online Only (Y/N) | N |
Additional Online Files (Y/N) | N |
Google Analytic Metrics | Metrics page |