[S-SS10] Strong Ground Motion and Earthquake Disaster

[SSS10-09] Rupture process of the 2024 Noto Peninsula earthquake

*Hongqi Diao¹, Hongjun Si¹, Kazuki Koketsu² (1.Seismological Research Institute Inc., 2.SFC Research Institute, Keio University)

Keywords:Noto Peninsula, source inversion, rupture process

The M_J 7.6 Noto Peninsula earthquake occurred in the northern part of the Noto Peninsula at 16:10:9 (local time, UTC+9) on January 1, 2024, which caused serious and widespread disasters. In this study we performed a joint inversion of teleseismic and strong motion waveforms to investigate the fault slip distribution and rupture process of this earthquake. Based on the known active fault traces, aftershock distribution and reported focal mechanisms, we first constructed a two-segment fault model, which consists of the northeast (NE) and southwest (SW) segments. The hypocenter (rupture initiation point) was located on the NE segment, whose strike and dip are consistent with the focal mechanism of the mainshock. The strike and dip of the SW segment were mainly determined according to the aftershock distribution. Then, we performed a joint source inversion using teleseismic waveforms from the Global Seismographic Network and strong motion waveforms recorded by K-NET and KiK-net. The results showed that the mainshock ruptured with a duration of about 50 s, releasing a total seismic moment of 2.42×10⁺²⁰ Nm, which corresponds to an M_w of 7.52. The asperities occurred in the shallow parts at depths smaller than 10 km on both NE and SW segments. Their maximum slips are 5 or 6 meters. The rupture began with small slips around the hypocenter in the first 10 s, then it propagated bilaterally from the hypocenter having larger slips. It generated the largest slips on both NE and SW segments 30 or 35 s after the origin time. The rupture lasted for about 45 s on the NE segment and 50 s on the SW segment.