Seasonal seismicity at western United States volcanic centers

Earth and Planetary Science Letters
By: , and 



We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions, statistically significant seasonal modulation of seismicity (> 90% probability) occurs, such that there is an increase in the monthly seismicity during a given portion of the year. In five regions, seasonal seismicity is significant in the upper 3 km of the crust. Peak seismicity occurs in the summer and autumn in Mt. St. Helens, Hebgen Lake/Madison Valley, Yellowstone Lake, and Mammoth Mountain. In the eastern south moat of Long Valley caldera (LVC) peak seismicity occurs in the winter and spring. We quantify the possible external forcing mechanisms that could modulate seasonal seismicity. Both snow unloading and groundwater recharge can generate large stress changes of > 5 kPa at seismogenic depths and may thus contribute to seasonality. ?? 2005 Elsevier B.V. All rights reserved.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Seasonal seismicity at western United States volcanic centers
Series title Earth and Planetary Science Letters
DOI 10.1016/j.epsl.2005.09.012
Volume 240
Issue 2
Year Published 2005
Language English
Publisher Elsevier
Contributing office(s) Volcano Hazards Program
Description 15 p.
First page 307
Last page 321
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