3:45 PM - 4:00 PM
[HDS11-12] Tsunami source area of the 2024 M7.6 Noto Peninsula earthquake estimated from the tsunami arrival times of the coastal tsunami records
Keywords:Noto Peninsula earthquake on January 1, 2024, Tsunami source area, Tsunami back-propagation, Toyama Bay
On January 1, 2024, at 16:10 (JST), a magnitude 7.6 earthquake occurred on the Noto Peninsula in central Japan. The resulting tsunami was observed along the coast of the Japan Sea. These tsunami data have been used to investigate the source characteristics of this earthquake and tsunami. However, the location and geometry of the seismic fault planes of this earthquake have not yet precisely determined. If the extent of the tsunami source area can be constrained by using the tsunami data without fault assumptions, it will contribute to estimate the detailed seismic and tsunami source distribution. In this study, we estimated tsunami source area of the Noto Peninsula earthquake using the tsunami arrival times of the coastal tsunami records.
To estimate the tsunami source area, we applied Huygen's principle to back-propagate tsunami from each observing point. Somewhere on each back-propagation line using the tsunami travel time from the corresponding observatory is expected to touch the edge of the tsunami source area; hence we can estimate the tsunami source area as an area surrounded by the back-propagation lines of the multiple stations. We used the arrival times of the initial tsunami waves at 11 stations along the Japan Sea coast (provisional values published by Japan Meteorological Agency). We assumed that the tsunami was generated instantaneously at the origin time of the M7.6 earthquake. For the calculation of the tsunami back-propagation, we used Geoware Tsunami Travel Time software and the bathymetric data (1 arc-sec resolution) that we prepared by combining the bathymetric data developed by the MEXT research project with the bathymetric information based on the nautical charts.
We found two characteristics of the estimated tsunami source area (Fig. 1). One is that the tsunami source area was approximately 100 km in length and extended to the east-northeast off the Noto Peninsula (red rectangle in Fig. 1), and the other is possible existence of an additional tsunami source in Toyama Bay. The eastern edge of the source area was constrained by back-propagation lines for which polarities of the initial waves were up (U), which suggest that uplifted displacement should be dominant in the sea area east of the Noto Peninsula. In contrast, the north and south edges of the source area were less constrained by few back-propagation lines, and the waveform analysis should be examined to clarify the north-south extent. The arrival time of 3 min after the earthquake at Toyama tide gauge implies the existence of an additional tsunami source in Toyama Bay. We will try to give more constraints on the locations of the additional tsunami sources by adding the analysis of tsunami arrival times at other locations (e.g., Minami et al., 2024, this meeting).
Acknowledgements. We used the bathymetric data developed by the MEXT research project in 2013-2020 fiscal year on earthquakes and tsunamis in the Japan Sea. We used sea depth information picked up from the nautical charts by the staffs in Seismology and Volcanology Department of Japan Meteorological Agency. This study was partly supported by JSPS KAKENHI Grant Number JP23K17482.
To estimate the tsunami source area, we applied Huygen's principle to back-propagate tsunami from each observing point. Somewhere on each back-propagation line using the tsunami travel time from the corresponding observatory is expected to touch the edge of the tsunami source area; hence we can estimate the tsunami source area as an area surrounded by the back-propagation lines of the multiple stations. We used the arrival times of the initial tsunami waves at 11 stations along the Japan Sea coast (provisional values published by Japan Meteorological Agency). We assumed that the tsunami was generated instantaneously at the origin time of the M7.6 earthquake. For the calculation of the tsunami back-propagation, we used Geoware Tsunami Travel Time software and the bathymetric data (1 arc-sec resolution) that we prepared by combining the bathymetric data developed by the MEXT research project with the bathymetric information based on the nautical charts.
We found two characteristics of the estimated tsunami source area (Fig. 1). One is that the tsunami source area was approximately 100 km in length and extended to the east-northeast off the Noto Peninsula (red rectangle in Fig. 1), and the other is possible existence of an additional tsunami source in Toyama Bay. The eastern edge of the source area was constrained by back-propagation lines for which polarities of the initial waves were up (U), which suggest that uplifted displacement should be dominant in the sea area east of the Noto Peninsula. In contrast, the north and south edges of the source area were less constrained by few back-propagation lines, and the waveform analysis should be examined to clarify the north-south extent. The arrival time of 3 min after the earthquake at Toyama tide gauge implies the existence of an additional tsunami source in Toyama Bay. We will try to give more constraints on the locations of the additional tsunami sources by adding the analysis of tsunami arrival times at other locations (e.g., Minami et al., 2024, this meeting).
Acknowledgements. We used the bathymetric data developed by the MEXT research project in 2013-2020 fiscal year on earthquakes and tsunamis in the Japan Sea. We used sea depth information picked up from the nautical charts by the staffs in Seismology and Volcanology Department of Japan Meteorological Agency. This study was partly supported by JSPS KAKENHI Grant Number JP23K17482.