5:15 PM - 7:15 PM
[SSS12-P02] Seismic activity related to the earthquakes occurred at Mutsu bay on November 2024 observed by dense regional network
Keywords:AS-net, Mutsu bay
M4.6 and M5.1 earthquakes occurred at the middle of Mutsu bay in Aomori prefecture on November 16th and 24th 2024 respectively. In this presentation we report the seismic activity and hypocenter distribution derived by using seismic data recorded by regional seismic network AS-net.
AS-net consists of 36 high-sensitivity seismic stations was installed and operated by Association for the Development of Earthquake Prediction (ADEP) at 2013 and 2014 (Noguchi et al., 2017). We have conducted our own hypocenter determination manually since 2014 using the AS-net and the other seismic stations. Our earthquake catalogue lists considerably more events around Shimokita peninsula or Mutsu bay than JMA unified catalogue which uses 20 stations of AS-net since December 2017.
Our catalogue and the unified catalogue indicate that a local seismic activity has existed at the middle of Mutsu bay. Less than 100 events have been detected as the seismic activity in this region in the decade from 2014 to 2023. From the latter August 2024 to just before the M4.6 and M5.1 earthquakes, dozens of earthquakes occurred in this seismic activity. The M4.6 and M5.1 earthquakes occurred respectively. Neither of these two earthquakes accompanied by any precursory earthquake just before (~1 hour). After these earthquakes 744 aftershocks were detected until the end of 2024. These aftershocks were dispersed with no clear order because of the absence of seismic station just above the activity area. The P-wave polarities of seismic records indicated the reverse faulting of the two earthquakes though the directions of strikes were not clear because of the geometry of the stations. These results are preliminary and we report more latest results by more analyses in our presentation.
Acknowledgement
We used seismic observation data derived by Japan Meteorological Agency, National Research Institute for Earth Science and Disaster Resilience, Hirosaki University, Tohoku University, Hokkaido University and Aomori Prefecture. We used hypocenter information listed on JMA hypocenter catalogue determined and distributed by Japan Meteorological Agency.
Reference
Noguchi, S., S. Sekine, Y. Sawada, K. Kasahara, S. Sasaki, Y. Tazawa, H. Yajima, Earthquake monitoring using dense local seismic network, AS-net, in northern Tohoku, Japan, 16th WCEE, Santiago, January 9-13, 2017, No. 3991.
AS-net consists of 36 high-sensitivity seismic stations was installed and operated by Association for the Development of Earthquake Prediction (ADEP) at 2013 and 2014 (Noguchi et al., 2017). We have conducted our own hypocenter determination manually since 2014 using the AS-net and the other seismic stations. Our earthquake catalogue lists considerably more events around Shimokita peninsula or Mutsu bay than JMA unified catalogue which uses 20 stations of AS-net since December 2017.
Our catalogue and the unified catalogue indicate that a local seismic activity has existed at the middle of Mutsu bay. Less than 100 events have been detected as the seismic activity in this region in the decade from 2014 to 2023. From the latter August 2024 to just before the M4.6 and M5.1 earthquakes, dozens of earthquakes occurred in this seismic activity. The M4.6 and M5.1 earthquakes occurred respectively. Neither of these two earthquakes accompanied by any precursory earthquake just before (~1 hour). After these earthquakes 744 aftershocks were detected until the end of 2024. These aftershocks were dispersed with no clear order because of the absence of seismic station just above the activity area. The P-wave polarities of seismic records indicated the reverse faulting of the two earthquakes though the directions of strikes were not clear because of the geometry of the stations. These results are preliminary and we report more latest results by more analyses in our presentation.
Acknowledgement
We used seismic observation data derived by Japan Meteorological Agency, National Research Institute for Earth Science and Disaster Resilience, Hirosaki University, Tohoku University, Hokkaido University and Aomori Prefecture. We used hypocenter information listed on JMA hypocenter catalogue determined and distributed by Japan Meteorological Agency.
Reference
Noguchi, S., S. Sekine, Y. Sawada, K. Kasahara, S. Sasaki, Y. Tazawa, H. Yajima, Earthquake monitoring using dense local seismic network, AS-net, in northern Tohoku, Japan, 16th WCEE, Santiago, January 9-13, 2017, No. 3991.