10:45 〜 11:00
[SSS04-06] Dynamically triggered seismicity in Japan following the 2024 Mw7.5 Noto earthquake
キーワード：2024 Noto earthquake, Dynamic triggering
On January 1st, 2024, a moment magnitude (Mw) 7.5 earthquake occurred on an active reverse fault in the northern part of Noto Peninsula, representing one of the largest intraplate events recorded in Japan. In previous studies, the remote dynamic triggering of microseismicity following some large earthquakes in Japan has been well documented, such as the case of the 2011 Mw9.0 Tohoku-oki earthquake (Miyazawa, 2011; Opris et al., 2017), the 2016 Mw7.0 Kumamoto earthquake (Enescu et al., 2016) or other large, remote earthquakes occurred worldwide (e.g., Takeda et al., 2024).
The purpose of this study is to investigate the remote triggering of earthquakes following the 2024 Noto earthquake, by analyzing the continuous waveform data recorded at Hi-net stations located at roughly more than 3 fault-lengths from the mainshock epicenter. Since static stresses attenuate faster with distance, we expect the triggering at such remote distances to be predominantly dynamic, caused by the passage of surface waves from the mainshock (e.g., Prejean and Hill, 2009).
Our results show relatively widespread activation of dynamically triggered small earthquakes (most of them are not listed in the JMA earthquake catalog) that were triggered by the passage of the mainshock's surface waves in many regions of Japan. These include Hokkaido and Tohoku in the northeastern region of Japan, to Kanto, in the central part and Kyushu, in the southern part of Japan. The triggering is mostly observed at volcanic regions, in agreement with previous research (e.g., Prejean and Hill, 2009) that shows such places are easier to be activated dynamically, likely due to the excitation of excessive fluids in such regions by the passage of surface waves. Figure 1 shows an example of dynamically triggered earthquakes observed at the Hi-net station NRKH, in Tohoku region. In the Onikobe volcanic area a small earthquake appears to be triggered during the passage of the surface waves of the Mw5.5 foreshock, occurred a few minutes before the Noto mainshock (Figure 1). Our next step is to investigate potential factors that control the susceptibility of dynamic triggering, including background seismicity rate, peak value and period of the dynamic stress, as well as the incoming angle of the surface waves.
The purpose of this study is to investigate the remote triggering of earthquakes following the 2024 Noto earthquake, by analyzing the continuous waveform data recorded at Hi-net stations located at roughly more than 3 fault-lengths from the mainshock epicenter. Since static stresses attenuate faster with distance, we expect the triggering at such remote distances to be predominantly dynamic, caused by the passage of surface waves from the mainshock (e.g., Prejean and Hill, 2009).
Our results show relatively widespread activation of dynamically triggered small earthquakes (most of them are not listed in the JMA earthquake catalog) that were triggered by the passage of the mainshock's surface waves in many regions of Japan. These include Hokkaido and Tohoku in the northeastern region of Japan, to Kanto, in the central part and Kyushu, in the southern part of Japan. The triggering is mostly observed at volcanic regions, in agreement with previous research (e.g., Prejean and Hill, 2009) that shows such places are easier to be activated dynamically, likely due to the excitation of excessive fluids in such regions by the passage of surface waves. Figure 1 shows an example of dynamically triggered earthquakes observed at the Hi-net station NRKH, in Tohoku region. In the Onikobe volcanic area a small earthquake appears to be triggered during the passage of the surface waves of the Mw5.5 foreshock, occurred a few minutes before the Noto mainshock (Figure 1). Our next step is to investigate potential factors that control the susceptibility of dynamic triggering, including background seismicity rate, peak value and period of the dynamic stress, as well as the incoming angle of the surface waves.