Seismoacoustic Insights From the May 22nd, 2016 Iliamna Volcano Rock and Ice Avalanche

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Landslides occur around the world and can have devastating impacts in populated areas. Seismoacoustic signals produced by these hazardous events may permit quick landslide location and characterization, even when they occur in remote regions. Such information could enable a more rapid and effective emergency response. Here, we jointly apply seismic and infrasound techniques to characterize a large rock and ice avalanche which occurred on Iliamna volcano, Alaska on May 22nd, 2016. Iliamna is a glacier-mantled composite stratovolcano located ~200 km from Anchorage, Alaska. The subglacial rocks near its summit are weakened by hydrothermal activity, resulting in sporadic catastrophic avalanches. Seismic signals from the May 22nd event were observed out to ~230 km on more than 20 stations in the region. The event also produced energetic acoustic signals recorded on at least 10 stations, including two arrays and six EarthScope Transportable Array (TA) stations. We model infrasound propagation via the AVO-G2S open-source atmospheric specification to separate acoustic source directionality from propagation-biased directionality. We also apply the transverse coherence minimization method (Haney, 2018) to select TA stations to determine the source velocity from backazimuth variation over time. We additionally perform a single-force inversion on very-long-period (20–250 s) seismic data from the event to determine the centroid force vector for the avalanche, which we compare to a traditional moment tensor inversion. Lastly, we relate our findings to independent information derived from remote sensing and land-based imagery. We aim for these analyses to eventually be useful in an operational real-time monitoring context.

Reference:

Haney, M. M. (2018). Volcanic explosion backazimuth from near-surface seismo-acoustic coupling minimization, Abstract NS44A-06 presented at the 2018 AGU Fall Meeting, Washington, D.C., 10–14 Dec.

Presenting Author: Liam D. Toney

Authors