17:15 〜 18:45
[U15-P20] 強震波形による2024年能登半島地震の震源破壊過程
キーワード：2024年能登半島地震、震源破壊過程、強震波形記録
Source rupture process of the 2024 Noto Hanto, Japan, earthquake (MJMA 7.6) was estimated by the kinematic waveform inversion of strong motion records. The multiple time-windows linear waveform inversion method (e.g., Hartzell and Heaton, 1983) was used to estimate the spatiotemporal rupture process during this earthquake. We analyzed the velocity waveforms in 0.03–0.5 Hz observed at strong motion stations surrounding the source region. The source fault model is assumed mainly referring to aftershock distributions and previously mapped seafloor faults. The assumed source faults extend from northwestern edge of the Noto Peninsula to the Toyama Trough.
Based on preliminary analysis of observed strong motion records, we propose two stages of ruptures on the source faults. The first rupture started at the hypocenter in Suzu at 16:10:09 on January 1, 2024 (JST), and the rupture propagated southwestward. Then, the second rupture started beneath Suzu during the first rupture was continuing, at 16:10:22, which was about 13 seconds after the first rupture starts, and the rupture propagated northeastward in the direction of the Toyama Trough. Large amount of slip (about 4-8 m) occurred beneath the northwestern part of the Noto Peninsula along the coastline about 20 seconds after the start of the first rupture, and this large-slip area mainly contributes to strong ground motions with large PGV observed in the Noto Peninsula. Finally, another large slip occurred beneath sea in northeast of the Noto Peninsula about 15 seconds after the second rupture started. Each event has a moment magnitude of MW 7.3, and the total magnitude of the 2024 Noto Hanto earthquake was estimated to be MW 7.5. The observed strong motion waveforms in Sado Island can be explained by the second rupture.
We will revise the source model referring to the latest information on the aftershock distributions and seafloor deformation reported by other institutes.
Acknowledgments: We used strong motion records of NIED K-NET, KiK-net, F-net, and JMA. This work was supported by MEXT KAKENHI 23K17482 (PI: Prof. Hiramatsu, Kanazawa Univ.).
Based on preliminary analysis of observed strong motion records, we propose two stages of ruptures on the source faults. The first rupture started at the hypocenter in Suzu at 16:10:09 on January 1, 2024 (JST), and the rupture propagated southwestward. Then, the second rupture started beneath Suzu during the first rupture was continuing, at 16:10:22, which was about 13 seconds after the first rupture starts, and the rupture propagated northeastward in the direction of the Toyama Trough. Large amount of slip (about 4-8 m) occurred beneath the northwestern part of the Noto Peninsula along the coastline about 20 seconds after the start of the first rupture, and this large-slip area mainly contributes to strong ground motions with large PGV observed in the Noto Peninsula. Finally, another large slip occurred beneath sea in northeast of the Noto Peninsula about 15 seconds after the second rupture started. Each event has a moment magnitude of MW 7.3, and the total magnitude of the 2024 Noto Hanto earthquake was estimated to be MW 7.5. The observed strong motion waveforms in Sado Island can be explained by the second rupture.
We will revise the source model referring to the latest information on the aftershock distributions and seafloor deformation reported by other institutes.
Acknowledgments: We used strong motion records of NIED K-NET, KiK-net, F-net, and JMA. This work was supported by MEXT KAKENHI 23K17482 (PI: Prof. Hiramatsu, Kanazawa Univ.).