10:45 〜 11:00
[J04-6-02] The Operational Result for GEONET Real-time Analysis System for Rapid Finite Fault Modeling
Geospatial Information Authority of Japan (GSI) has been continuously operating the REGARD (Real-time GEONET Analysis system for Rapid Deformation monitoring; for more detail see Kawamoto et al., 2017 in this symposium), which estimates earthquake fault model in real-time from 1-Hz GNSS observation, since 2015. REGARD has successfully observed the co-seismic displacements and estimated the finite fault model for some earthquakes of ~M7 since it ran.
Mainshock (M7.3) and two foreshock (M6.5 and M6.4, respectively) hit inland area of western Japan in the 2016 Kumamoto earthquake. The co-seismic displacements of about 100cm at most were observed from 1-Hz kinematic positioning, which was consistent with the result of GEONET F3 solution. REGARD system calculated that Mw of the mainshock is 6.85 in 58 seconds from event origin time. The final fault model of REGARD was estimated along the Futagawa fault zone within 6 minutes. This result is consistent with the evaluation by the Headquarters for Earthquake Research Promotion, which reports that the Kumamoto earthquake is considered to be mainly due to the activity of the Futagawa fault zone.
REGARD was able to detect the crustal deformation for other two earthquakes: one occurred at Tottori prefecture, western part of Japan, on 21th October 2016 (M6.6) and the other occurred off the Pacific coast of Tohoku region on 22th November 2016 (M7.4). However, the estimated finite fault model was slightly longer than the post-processed rectangular fault model by GSI for the case of Tottori, which led the overestimation of Mw, and the solution converted to the conjugate fault for the Tohoku because signal-to-noise ratio of GNSS kinematic positioning results were relatively small compared with the mainshock of Kumamoto earthquake. Further studies are needed to enhance the fault model estimation process for M6-7 class earthquakes, e.g. prepare more accurate initial condition and/or set multiple initial condition.
Mainshock (M7.3) and two foreshock (M6.5 and M6.4, respectively) hit inland area of western Japan in the 2016 Kumamoto earthquake. The co-seismic displacements of about 100cm at most were observed from 1-Hz kinematic positioning, which was consistent with the result of GEONET F3 solution. REGARD system calculated that Mw of the mainshock is 6.85 in 58 seconds from event origin time. The final fault model of REGARD was estimated along the Futagawa fault zone within 6 minutes. This result is consistent with the evaluation by the Headquarters for Earthquake Research Promotion, which reports that the Kumamoto earthquake is considered to be mainly due to the activity of the Futagawa fault zone.
REGARD was able to detect the crustal deformation for other two earthquakes: one occurred at Tottori prefecture, western part of Japan, on 21th October 2016 (M6.6) and the other occurred off the Pacific coast of Tohoku region on 22th November 2016 (M7.4). However, the estimated finite fault model was slightly longer than the post-processed rectangular fault model by GSI for the case of Tottori, which led the overestimation of Mw, and the solution converted to the conjugate fault for the Tohoku because signal-to-noise ratio of GNSS kinematic positioning results were relatively small compared with the mainshock of Kumamoto earthquake. Further studies are needed to enhance the fault model estimation process for M6-7 class earthquakes, e.g. prepare more accurate initial condition and/or set multiple initial condition.