Remote Detection and Location of Explosive Volcanism in Alaska With the EarthScope Transportable Array

Abstract

The current deployment of the EarthScope Transportable Array (TA) in Alaska affords an unprecedented opportunity to study explosive volcanic eruptions using a relatively dense regional seismoacoustic network. Infrasound monitoring has demonstrated utility for the remote (>250 km range) detection and characterization of volcanic explosions, but previous studies have used relatively sparse regional or global networks. Seventy explosive events from the locally unmonitored Bogoslof volcano (2016-2017) provide a unique validation data set to examine the ability of the TA and other regional networks to detect and locate remote explosive volcanic eruptions in Alaska. With a simple envelope-based reverse time migration (RTM) technique, we are able to detect and locate more than 72% of the 61 Bogoslof infrasound events detected by the Alaska Volcano Observatory. Notably, RTM using only sparse regional infrasound arrays produces results similar to when incorporating the extensive single-sensor TA network, likely due to favorable signal-to-noise ratios, seasonal propagation conditions, and source-receiver geometries. Our implementation also detects and locates explosive eruptions from Cleveland volcano, Alaska, and Bezymianny volcano, Kamchatka, as well as infrasound from nonvolcanic events such as earthquakes. We characterize the success of the RTM algorithm and associated parameter choices using receiver operating characteristic curves, event detection rates, and location accuracy. Our methods are useful for explosive volcanic and nonvolcanic event detection and localization using real-time data and for scanning continuous waveform data archives.

Evaluating the applicability of a screen diffraction approximation to local volcano infrasound

“…Additionally, atmospheric variability can change the propagation conditions over short time periods [e.g. Chunchuzov et al 2011;de Groot-Hedlin 2017;Fee and Garcés 2007;Green et al 2012;Iezzi et al 2018;Johnson et al 2012;Matoza et al 2009;Ortiz et al 2018;Sanderson et al 2020]. For example, changes in atmospheric conditions in the boundary layer (lowermost "3 km of troposphere) caused up to "10 dB pressure differences in recordings of controlled chemical explosions at local distances [<10 km; Kim et al 2018].…”

Seismo-acoustic characterisation of the 2018 Ambae (Manaro Voui) eruption, Vanuatu

“…Observations and modelling to date indicate that air-to-ground coupling (propagating at acoustic velocity) is more common given volcanic source and velocity structure configurations than groundto-air coupling (propagating at seismic, e.g., Rayleigh wave velocity Matoza et al (2009)), although both ground-air and air-ground coupling have been documented in seismoacoustic publications (Blom et al 2020). Air-to-ground conversions or ground-coupled airwaves have been observed in local to remote volcano monitoring systems (Hagerty et al 2000;Johnson and Malone 2007;De Angelis et al 2012;Ichihara et al 2012;Matoza and Fee 2014;Fee et al 2016;Ichihara 2016;Nishida and Ichihara 2016;Smith et al 2016;Matoza et al 2018;Mckee et al 2018;Haney et al 2020;Kurokawa and Ichihara 2020;Sanderson et al 2020).…”

“…To check for air-to-ground-coupled waves in seismograms, (1) cross-correlation (Ichihara et al 2012), (2) coherence (Matoza and Fee 2014), (3) response function (Ichihara, 2016;Kurokawa and Ichihara, 2020), and (4) reverse-time migration (RTM) have been applied. Variations on the RTM method include back projection, stacking, source scanning, and time-reversal (e.g., Walker et al 2011;De Angelis et al 2012;Jolly et al 2014;Sanderson et al 2020). This approach is originally used to locate seismic (Ishii et al 2005;Kiser and Ishii 2011) and acoustic (Jolly et al 2014;Sanderson et al 2020;Fee et al 2021) sources related to volcanic eruptions, while here we identified the dominant propagation velocity across a seismic network.…”

“…Variations on the RTM method include back projection, stacking, source scanning, and time-reversal (e.g., Walker et al 2011;De Angelis et al 2012;Jolly et al 2014;Sanderson et al 2020). This approach is originally used to locate seismic (Ishii et al 2005;Kiser and Ishii 2011) and acoustic (Jolly et al 2014;Sanderson et al 2020;Fee et al 2021) sources related to volcanic eruptions, while here we identified the dominant propagation velocity across a seismic network. For the Ambae eruptions, the dominant frequency band of acoustic waves significantly differs from that of seismic tremor (Fig.…”

Ps‐P Tomography of a Midcrustal Magma Reservoir Beneath Cleveland Volcano, Alaska

“…Cleveland Volcano is an andesitic stratovolcano within the volcanic complex known as the Islands of the Four Mountains (Figure 1). As one of the most active volcanoes in the Aleutian arc, its magmatic processes are of particular interest, but its relative inaccessibility has led to a reliance on remote sensing techniques to characterize ash plumes and lava flows (Dean et al, 2004), explosions (De Angelis et al, 2012;Sanderson et al, 2020), dome growth (Wang et al, 2015), and gas emissions (Werner et al, 2017(Werner et al, , 2020 at the volcano. However, analyses of newly collected seismic data (Roman, 2015) have indicated that seismicity is limited to the upper (<10 km b.s.l.)…”