17:15 〜 18:30
[SCG48-P01] Seismicity of Deep Long-Period events in Eastern Shimane Revealed by Campaign Observations
キーワード：深部低周波地震、深部長周期地震、地震活動
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). As well as 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 tectonic LFEs are known to be slip events, the physical mechanism of volcanic DLPs is unclear yet. Specifically, we need to understand both the excitation mechanism driving the phenomena and the resonance mechanism responsible for harmonic seismic waves.
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].
In this study, we focus on the seismicity of DLPs in Eastern Shimane to quantify the swarm-like characteristics. First, we carry out matched-filter detection using our campaign observations' data and Hi-net records. Then, we quantify the seismicity using the event catalog. In specific, we fit the inter-event statistics by Weibull distribution and generalized gamma distribution. We discuss the physical mechanisms of DLPs by comparing the fitting parameters with ordinary events and tectonic LFEs.
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].
In this study, we focus on the seismicity of DLPs in Eastern Shimane to quantify the swarm-like characteristics. First, we carry out matched-filter detection using our campaign observations' data and Hi-net records. Then, we quantify the seismicity using the event catalog. In specific, we fit the inter-event statistics by Weibull distribution and generalized gamma distribution. We discuss the physical mechanisms of DLPs by comparing the fitting parameters with ordinary events and tectonic LFEs.