S031-0003
Campaign Observations of Deep Long-Period Earthquakes in Eastern Shimane
Campaign Observations of Deep Long-Period Earthquakes in Eastern Shimane
Thursday, 10 December 2020
Poster
Abstract:
Deep long-period earthquakes (DLPs) are deep (~10–45 km) earthquakes that radiate long-period (~2–8Hz) seismic waves despite their small magnitude (M<2). With tectonic low-frequency earthquakes (LFEs) on plate interfaces, volcanic DLPs widely observed in volcanic regions are unique slow deformation processes that exist in nature. While we regard tectonic LFEs as slip events, the physical mechanism of volcanic DLPs is unclear yet. Specifically, we need to understand the excitation mechanism driving the phenomena and the resonance mechanism responsible for harmonic seismic waves, which need to be consistent with each other. The excitation mechanism could be not only tectonic effects but also thermal stress caused by a cooling magma body [Aso and Tsai, 2014].
To understand the physics of volcanic DLPs, we need to examine various observational facts. They include significant distribution around active volcanoes with secondary distribution apart from volcanic fronts [Aso et al., 2011, 2013; Vidale et al., 2014], depth distribution roughly around the Moho [Hasegawa et al., 1991; Nichols et al., 2011], frequent observation of significant non-double-couple components [Nakamichi et al., 2003; Aso and Ide, 2014; Oikawa et al., 2019], and a possible response to volumetric stress [Han et al., 2018].
The seismic source process is fundamentally essential for understanding their genesis. Especially, we are interested in the initial process to understand the excitation mechanism. We carry out campaign observations to investigate the very early part of the DLP events this year. In this presentation, we introduce the observed data and show our waveform modeling consistent with the campaign data and Hi-net records.
To understand the physics of volcanic DLPs, we need to examine various observational facts. They include significant distribution around active volcanoes with secondary distribution apart from volcanic fronts [Aso et al., 2011, 2013; Vidale et al., 2014], depth distribution roughly around the Moho [Hasegawa et al., 1991; Nichols et al., 2011], frequent observation of significant non-double-couple components [Nakamichi et al., 2003; Aso and Ide, 2014; Oikawa et al., 2019], and a possible response to volumetric stress [Han et al., 2018].
The seismic source process is fundamentally essential for understanding their genesis. Especially, we are interested in the initial process to understand the excitation mechanism. We carry out campaign observations to investigate the very early part of the DLP events this year. In this presentation, we introduce the observed data and show our waveform modeling consistent with the campaign data and Hi-net records.