Observations of volcanic tremor during January-February 2005 eruption of Mt. Veniaminof, Alaska

Bulletin of Volcanology
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Abstract

Mt. Veniaminof, Alaska Peninsula, is a stratovolcano with a summit ice-filled caldera containing a small intracaldera cone and active vent. From January 2 to February 21, 2005, Mt. Veniaminof erupted. The eruption was characterized by numerous small ash emissions (VEI 0 to 1) and accompanied by low-frequency earthquake activity and volcanic tremor. We have performed spectral analyses of the seismic signals in order to characterize them and to constrain their source. Continuous tremor has durations of minutes to hours with dominant energy in the band 0.5– 4.0 Hz, and spectra characterized by narrow peaks either irregularly (non-harmonic tremor) or regularly spaced (harmonic tremor). The spectra of non-harmonic tremor resemble those of low-frequency events recorded simultaneously with surface ash explosions, suggesting that the source mechanisms might be similar or related. We propose that non-harmonic tremor at Mt. Veniaminof results from the coalescence of gas bubbles while low-frequency events are related to the disruption of large gas pockets within the conduit. Harmonic tremor, characterized by regular and quasisinusoidal waveforms, has duration of hours. Spectra containing up to five harmonics suggest the presence of a resonating source volume that vibrates in a longitudinal acoustic mode. An interesting feature of harmonic tremor is that frequency is observed to change over time; spectral lines move towards higher or lower values while the harmonic nature of the spectra is maintained. Factors controlling the variable characteristics of harmonic tremor include changes in acoustic velocity at the source and variations of the effective size of the resonator.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Observations of volcanic tremor during January-February 2005 eruption of Mt. Veniaminof, Alaska
Series title Bulletin of Volcanology
DOI 10.1007/s00445-007-0119-4
Volume 69
Year Published 2007
Language English
Publisher Springer-Link
Publisher location Berlin
Contributing office(s) Volcano Hazards Program
Description 14 p.
First page 927
Last page 940
Country United States
State Alaska
County Lake and Peninsula Borough
Online Only (Y/N) N
Additional Online Files (Y/N) N