Multiplets: Their behavior and utility at dacitic and andesitic volcanic centers

Journal of Geophysical Research B: Solid Earth
By: , and 

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Abstract

Multiplets, or groups of earthquakes with similar waveforms, are commonly observed at volcanoes, particularly those exhibiting unrest. Using triggered seismic data from the 1980-1986 Mount St. Helens (MSH) eruption, we have constructed a catalog of multiplet occurrence. Our analysis reveals that the occurrence of multiplets is related, at least in part, to the viscosity of the magma. We also constructed catalogs of multiplet occurrence using continuous seismic data from the 2004 eruption at MSH and 2007 eruption at Bezymianny Volcano, Russia. Prior to explosions at MSH in 2004 and Bezymianny in 2007, the multiplet proportion of total seismicity (MPTS) declined, while the average amplitudes and standard deviations of the average amplitude increased. The life spans of multiplets (time between the first and last event) were also shorter prior to explosions than during passive lava extrusion. Dome-forming eruptions that include a partially solidified plug, like MSH (1983-1986 and 2004-2008), often possess multiplets with longer life spans and MPTS values exceeding 50%. Conceptually, the relatively unstable environment prior to explosions is characterized by large and variable stress gradients brought about by rapidly changing overpressures within the conduit. We infer that such complex stress fields affect the number of concurrent families, MPTS, average amplitude, and standard deviation of the amplitude of the multiplets. We also argue that multiplet detection may be an important new monitoring tool for determining the timing of explosions and in forecasting the type of eruption.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Multiplets: Their behavior and utility at dacitic and andesitic volcanic centers
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/2010JB007924
Volume 116
Issue 8
Year Published 2011
Language English
Publisher American Geophysical Union
Publisher location Washington, D.C.
Contributing office(s) Hawaiian Volcano Observatory
Description 16 p.; B08210
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Geophysical Research B: Solid Earth