Slow rupture in a fluid-rich fault zone initiated the 2024 <i>M</i> <sub>w</sub> 7.5 Noto earthquake
Zhangfeng Ma, Hongyu Zeng, Haipeng Luo, Zemin Liu, Yu Jiang, Yosuke Aoki, Weitao Wang, Yuji Itoh, Mingzhe Lyu, Yan Cui, Sang‐Ho Yun, Emma M. Hill, Shengji Wei
Abstract
The 2024 moment magnitude 7.5 Noto Peninsula (Japan) earthquake caused devastation to communities and was generated by a complex rupture process. Using space geodetic and seismic observations, we have shown that the event deformed the peninsula with a peak uplift reaching 5 meters at the west coast. Shallow slip exceeded 10 meters on an offshore fault. Peak stress drop was greater than 10 megapascals. This devastating event began with a slow rupture propagation lasting 15 to 20 seconds near its hypocenter, where seismic swarms had surged since 2020 because of lower-crust fluid supply. The slow start was accompanied by intense high-frequency seismic radiation. These observations suggest a distinct coseismic slip mode reflecting high heterogeneity in fault properties within a fluid-rich fault zone.