10:45 〜 12:15
[SCG45-P37] Spatio-temporal evolution of slow slip events along the southern Ryukyu subduction zone in southwestern Japan estimated from a GNSS network, during 2016-2022
キーワード：SSE、GNSS
Slow slip events (SSEs) are transient aseismic fault slip events, which are identified in the plate subduction zones along the Pacific Rim by Global Navigation Satellite System (GNSS) over the past two decades (e.g., Hirose et al. 1999; Dragart et al., 2001; Lowry et al., 2001; Douglas et al., 2005). SSEs with a moment magnitude (Mw) ranges of 6.6 to 6.7, with durations of ∼1–2 months have been observed at an interval of approximately 6 months beneath the Yaeyama Islands along the southern Ryukyu subduction zone in the most southwestern part of Japan (e.g., Heki and Kataoka, 2008, Kano et al., 2018). The plate convergence rate beneath the Yaeyama Islands is 12–13 cm/year, consisting of the subduction of the Philippine sea plate northwestward at a rate of 8.0–8.5 cm/year (Sella et al., 2002) beneath the Ryukyu Arc and the southward back-arc spreading at a rate of 3.5–5.0 cm/year (Nishimura et al., 2004) along the Okinawa trough (Sibuet et al., 1998).
We analyze GNSS data of GEONET stations operated by the Geospatial Information Authority of Japan from 2016 to 2022 around the Yaeyama Islands. We apply a modified Network Inversion Filter (Fukuda et al., 2008) to estimate daily slip and slip rate on the plate interface. The geometry of the upper surface of the Philippine Sea plate is given by Hayes et al. (2012).
Our results show 12 SSEs occurred for the period from March to May 2016, October to December 2016, May to July 2017, December 2017 to January 2018, August to October 2018, January to March 2019, July to September 2019, January to March 2020, August to October 2020, March to April 2021, September to November 2021, and June to August 2022, respectively. Total slip and moment magnitude are estimated to be ~6.0-11.3 cm and ~6.4-6.7, respectively. The spatial distribution of slip is quite similar, and the peak of slip located ~30 km Northwest of Iriomote Island at a depth of 50 km. We will present the spatiotemporal evolution of slip and slip rate during the 12 SSEs varies from event to event.
We analyze GNSS data of GEONET stations operated by the Geospatial Information Authority of Japan from 2016 to 2022 around the Yaeyama Islands. We apply a modified Network Inversion Filter (Fukuda et al., 2008) to estimate daily slip and slip rate on the plate interface. The geometry of the upper surface of the Philippine Sea plate is given by Hayes et al. (2012).
Our results show 12 SSEs occurred for the period from March to May 2016, October to December 2016, May to July 2017, December 2017 to January 2018, August to October 2018, January to March 2019, July to September 2019, January to March 2020, August to October 2020, March to April 2021, September to November 2021, and June to August 2022, respectively. Total slip and moment magnitude are estimated to be ~6.0-11.3 cm and ~6.4-6.7, respectively. The spatial distribution of slip is quite similar, and the peak of slip located ~30 km Northwest of Iriomote Island at a depth of 50 km. We will present the spatiotemporal evolution of slip and slip rate during the 12 SSEs varies from event to event.