Time-lapse Seismic Velocity Changes Coincident With Dome Emplacement at Great Sitkin Volcano, Alaska
Ambient noise seismic methods are advantageous for volcano monitoring during relatively quiet time periods, for example when ocean-generated noise dominates over any continuous volcanic seismicity such as tremor. Great Sitkin Volcano in Alaska began an effusive dome-building eruption in late July 2021 that was characterized by low levels of seismicity. This effusive phase followed a Vulcanian explosion on May 26, 2021 and, by the beginning of 2022, had produced a lava dome at the summit of the volcano with a volume of approximately 30 million cubic meters. The 2021 eruption was preceded by years of elevated earthquake activity at the volcano.
We observe a clear increase in relative seismic velocity on the order of 0.5% coincident with the extrusion of the dome at Great Sitkin. Comparable velocity changes have been associated with domes at other volcanoes such as Merapi (velocity increase during dome growth) and Montserrat (velocity decrease after dome destruction). We detect the velocity increase at Great Sitkin using coda wave interferometry applied to ambient noise correlations in the 0.5-2 Hz frequency band using 4 broadband seismic stations located on the slopes of the volcano. The 4 seismic stations yield 10 total correlations for analysis: 6 cross-correlations and 4 auto-correlations. By applying a tomographic method to spatially localize the lateral location of the velocity changes, we find the area of largest change is not centered on the volcano’s summit; it instead lies roughly 3-4 km to the northwest. This part of the volcano consists of a geologically recent (< 10,000 years old) caldera structure interpreted to have formed from large-scale edifice failure toward the northwest. We hypothesize that the shallow subsurface (< 2 km depth) on this northwestern side of Great Sitkin is weaker and has a relatively higher velocity susceptibility to the applied stress caused by the weight of the dome and subsidence of the volcano.
Session: Advances in the Use of Seismic and Acoustic Methods to Constrain Physical Processes at Volcanoes [Poster]
Type: Poster
Room: Evergreen Ballroom
Date: 4/22/2022
Presentation Time: 08:00 AM Pacific
Presenting Author: Matthew M. Haney
Student Presenter: No
Additional Authors
Matthew Haney Presenting Author Corresponding Author mhaney@usgs.gov U.S. Geological Survey |
David Miller dmiller36@wisc.edu University of Wisconsin-Madison |
Alicia Hotovec-Ellis ahotovec-ellis@usgs.gov U.S. Geological Survey |
Clifford Thurber cthurber@wisc.edu University of Wisconsin-Madison |
Hannah Dietterich hdietterich@usgs.gov U.S. Geological Survey |
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Time-lapse Seismic Velocity Changes Coincident With Dome Emplacement at Great Sitkin Volcano, Alaska
Category
Advances in the Use of Seismic and Acoustic Methods to Constrain Physical Processes at Volcanoes
Description