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Broadband characteristics of earthquakes recorded during a dome-building eruption at Mount St. Helens, Washington, between October 2004 and May 2005: Chapter 5 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

Professional Paper 1750-5

This report is Chapter 5 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006. For more information, see: Professional Paper 1750
By:
, ,
Edited by:
David R. Sherrod, William E. Scott, Peter H. Stauffer

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Abstract

From October 2004 to May 2005, the Center for Earthquake Research and Information of the University of Memphis operated two to six broadband seismometers within 5 to 20 km of Mount St. Helens to help monitor recent seismic and volcanic activity. Approximately 57,000 earthquakes identified during the 7-month deployment had a normal magnitude distribution with a mean magnitude of 1.78 and a standard deviation of 0.24 magnitude units. Both the mode and range of earthquake magnitude and the rate of activity varied during the deployment. We examined the time domain and spectral characteristics of two classes of events seen during dome building. These include volcano-tectonic earthquakes and lower-frequency events. Lower-frequency events are further classified into hybrid earthquakes, low-frequency earthquakes, and long-duration volcanic tremor. Hybrid and low-frequency earthquakes showed a continuum of characteristics that varied systematically with time. A progressive loss of high-frequency seismic energy occurred in earthquakes as magma approached and eventually reached the surface. The spectral shape of large and small earthquakes occurring within days of each other did not vary with magnitude. Volcanic tremor events and lower-frequency earthquakes displayed consistent spectral peaks, although higher frequencies were more favorably excited during tremor than earthquakes.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Broadband characteristics of earthquakes recorded during a dome-building eruption at Mount St. Helens, Washington, between October 2004 and May 2005: Chapter 5 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006
Series title:
Professional Paper
Series number:
1750-5
Year Published:
2008
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Volcano Hazards Program
Description:
14 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
First page:
97
Last page:
110
Number of Pages:
14
Country:
United States
State:
Washington
Other Geospatial:
Mount St. Helens