Time‐Lapse Monitoring of Seismic Velocity Associated With 2011 Shinmoe‐Dake Eruption Using Seismic Interferometry: An Extended Kalman Filter Approach

Abstract

Seismic interferometry is a powerful tool to monitor the seismic velocity change associated with volcanic eruptions. For the monitoring, changes in seismic velocity with environmental origins (such as precipitation) are problematic. In order to model the environmental effects, we propose a new technique based on a state-space model. An extended Kalman filter estimates seismic velocity changes as state variables, with a first-order approximation of the stretching method. We apply this technique to three-component seismic records in order to detect the seismic velocity change associated with the Shinmoe-dake eruptions in 2011 and 2018. First, ambient noise cross correlations were calculated from May 2010 to April 2018. We also modeled seismic velocity changes resulting from precipitation and the 2016 Kumamoto earthquake, with exponential type responses. Most of the results show no significant changes associated with the eruptions, although gradual inflation of the magma reservoir preceded the 2011 eruption by 1 year. The observed low sensitivity to static stress changes suggests that the fraction of geofluid and crack density at about 1-km depth is small, and the crack shapes could be circular. Only one station pair west of the crater shows the significant drop associated with the eruption in 2011. The gradual drop of seismic velocity up to 0.05% preceded the eruption by 1 month. When the gradual drop began, volcanic tremors were activated at about 2-km depth. These observations suggest that the drop could be caused by damage accumulation due to vertical magma migration beneath the summit.

Permutation entropy variations in seismic noise before and after eruptive activity at Shinmoedake volcano, Kirishima complex, Japan

“…We calculate PE for the vertical component of stations SMN, SMW, KIOH, KRS, and TKS after bandpass filtering the continuous waveforms between 1 and 7 Hz. This band corresponds mostly to volcanic activity and minimizes contributions from other sources, such as meteorological conditions or anthropogenic noise (Nishida et al 2020). Bandt and Pompe (2002) recommended that m = 3,…,7, L = 1 and W > > m!…”

“…The decreasing PE pattern before the 2018 eruption was less clear at all stations. The seismicity, tilt, and seismic velocity records also exhibited no significant precursory signals prior to the eruption and this was probably caused by the rapid ascent of magma (Yamada et al 2019;Nishida et al 2020;Matsumoto and Geshi 2021). Another possibility is that the decreasing pattern occurred several months prior to the 2018 eruption and the observation period of PE needs to be extended in order to identify such a decrease.…”

“…Seismic noise cross-correlation has long been utilized as a tool for monitoring velocity changes at active volcanoes both in terms of spatial and temporal variations (e.g., Brenguier et al 2008;Obermann et al 2011). This methodology was applied to seismic noise recorded at Shinmoedake; however, the results revealed only minor changes in seismic velocity prior to the 2011 eruption and very little change before the 2017-2018 eruptions (Nishida et al 2020). In this work we use seismic noise in order to calculate Permutation Entropy (hereafter referred to as PE) and reconstruct its temporal variation prior to and during the three eruption cycles at Shinmoedake.…”

Seismic Scattering Property Changes Correlate With Ground Deformation at Suwanosejima Volcano, Japan

“…Plain Language Summary Continuous estimation of seismic velocity and seismic scattering property changes by passive interferometry using seismic ambient noise is a promising tool for monitoring volcanoes (Brenguier et al, 2008, https://doi.org/10.1038/ngeo104; Budi-Santoso & Lesage, 2016, https://doi.org/10.1093/gji/ggw145; Donaldson et al, 2019, https://doi.org/10.1126/sciadv.aax6642; Machacca-Puma et al, 2019, https://doi.org/10.1016/j.jvolgeores.2019.05.014; Nishida et al, 2020, https://doi. org/10.1029/2020jb020180).…”

“…Continuous estimation of seismic velocity and seismic scattering property changes by passive interferometry using seismic ambient noise (Curtis et al, 2006;Shapiro & Campillo, 2004) is a promising tool for monitoring volcanoes. Many previous studies have reported seismic velocity changes related to volcanic activity (Brenguier et al, 2008;Budi-Santoso & Lesage, 2016;Donaldson et al, 2017Donaldson et al, , 2019Hirose et al, 2017;Machacca-Puma et al, 2019;Nishida et al, 2020;Takano et al, 2017). In many cases, seismic velocity changes beneath volcanoes have been interpreted to be due to crack opening or closing by stress changes from magma pressurization.…”