The 2004–2008 dome-building eruption at Mount St. Helens, Washington: Epilogue

Bulletin of Volcanology
By: , and 

Links

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

Additional publication details

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
Additional metadata about this publication, not found in other parts of the page is in this table