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[U15-P74] Tsunami Measured on the Toyama Bay Coast Caused by the 2024 Noto Peninsula Earthquake
Keywords:live camera, Noto Peninsula earthquake, Toyama Bay coast, tsunami arrival time, tsunami field survey, tsunami source area
1. Introduction
On January 1, 2024, a magnitude 7.6 intraplate earthquake (Noto Peninsula earthquake) occurred in the Noto District, central Japan, and a tsunami was widely observed along the coast of the Japan Sea from Hokkaido to Kyushu (Earthquake Research Committee, January 2, 2024). The earliest detected tsunami reported in the "Monthly Report on Earthquakes and Volcanoes in January 2024" (Japan Meteorological Agency (JMA), 2024) was a downward tsunami observed at the Toyama Tide Station 3 min after the seismic origin time (OT). Tsushima et al. (2024, JpGU2024 HDS11-12) estimated the tsunami source area by backpropagation based on the arrival time of the tsunami at each tide station and then pointed out the probable existence of a tsunami source near the Toyama Tide Station in addition to the tsunami source generated by crustal deformation caused by the Noto Peninsula earthquake. We conducted tsunami field surveys, focusing on the coast of Toyama Bay. In the surveys, we not only measured tsunami heights but also collected other observational data to extract the maximum wave heights and the arrival times of tsunamis that may have originated from tsunami sources in Toyama Bay.
2. Tsunami height obtained from field survey
In January and March, a team visited the coast between Nanao City, Ishikawa Prefecture and Kurobe City, Toyama Prefecture. Tsunami heights were obtained at the following four points based on tsunami traces (a, c, d), interviews with local residents and facility users (a, c), and comparison of local conditions with the water surface at the maximum water level using live camera images (b, d).
a. Shimosazanami Fishing Port, Nanao City: 2.0 m and 2.4 m (run-up height)
b. Amaharashi Beach, Takaoka City: 1.1m (inundation height)
c. Kairyushinmachi, Imizu City: 1.5m (run-up height)
d. Iwasehama, Toyama City: 2.2 m (run-up height)
In addition, a field survey conducted by the Toyama Local Meteorological Office obtained a tsunami run-up height of 1.3 m at the Miyazaki fishing port in Asahi Town on the east coast of Toyama Bay (JMA, 2024). Based on these results and tsunami heights observed at tide stations, the maximum tsunami heights along the coast of Toyama Prefecture are generally 0.5 to just over 2 m.
3. Tsunami arrival time obtained from live camera analysis
We do not receive any eyewitness information that would lead to the exact arrival time of the tsunami because most of the respondents evacuated appropriately during the issuance of the tsunami warning. We extracted the polarity and arrival time of the initial tsunami wave from the observation data at each tide station along the coast of Toyama Bay: downward at about 4 min + OT at Ikuji, Kurobe City, and upward at about 3 min + OT at Fushiki-Toyama, Takaoka City. In addition, Minami et al. (2024, JpGU2024 HDS11-11) extracted tsunami time series waveforms by analyzing live camera movies recorded by broadcasting companies from fixed viewpoints. The polarity and arrival time of the initial tsunami wave at the Amaharashi coast, Takaoka City, were upward at about 7 min + OT. As described above, we confirmed that tsunamis arrived early (3–7 min + OT) at various points along the coast of Toyama Bay.
4. Conclusion
The early-arriving tsunamis are confirmed along the Toyama Bay coast at locations other than the Toyama Tide Station. The maximum tsunami heights along the Toyama Bay coast are generally 0.5 to just over 2 m. These results will provide important constraints for the detailed estimation of tsunami sources in Toyama Bay due to the Noto Peninsula earthquake.
Acknowledgements:
Takaoka Cable Network Co. Ltd., and Cable Television Toyama Inc. provided live camera movies at Amaharashi Beach and Iwasehama, respectively. Observation data from tide stations operated by the Ports and Harbours Bureau, and the Water and Disaster Management Bureau were also used in this study. This research was partially supported by a Grant-in-Aid for Scientific Research (KAKENHI 23K17482).
On January 1, 2024, a magnitude 7.6 intraplate earthquake (Noto Peninsula earthquake) occurred in the Noto District, central Japan, and a tsunami was widely observed along the coast of the Japan Sea from Hokkaido to Kyushu (Earthquake Research Committee, January 2, 2024). The earliest detected tsunami reported in the "Monthly Report on Earthquakes and Volcanoes in January 2024" (Japan Meteorological Agency (JMA), 2024) was a downward tsunami observed at the Toyama Tide Station 3 min after the seismic origin time (OT). Tsushima et al. (2024, JpGU2024 HDS11-12) estimated the tsunami source area by backpropagation based on the arrival time of the tsunami at each tide station and then pointed out the probable existence of a tsunami source near the Toyama Tide Station in addition to the tsunami source generated by crustal deformation caused by the Noto Peninsula earthquake. We conducted tsunami field surveys, focusing on the coast of Toyama Bay. In the surveys, we not only measured tsunami heights but also collected other observational data to extract the maximum wave heights and the arrival times of tsunamis that may have originated from tsunami sources in Toyama Bay.
2. Tsunami height obtained from field survey
In January and March, a team visited the coast between Nanao City, Ishikawa Prefecture and Kurobe City, Toyama Prefecture. Tsunami heights were obtained at the following four points based on tsunami traces (a, c, d), interviews with local residents and facility users (a, c), and comparison of local conditions with the water surface at the maximum water level using live camera images (b, d).
a. Shimosazanami Fishing Port, Nanao City: 2.0 m and 2.4 m (run-up height)
b. Amaharashi Beach, Takaoka City: 1.1m (inundation height)
c. Kairyushinmachi, Imizu City: 1.5m (run-up height)
d. Iwasehama, Toyama City: 2.2 m (run-up height)
In addition, a field survey conducted by the Toyama Local Meteorological Office obtained a tsunami run-up height of 1.3 m at the Miyazaki fishing port in Asahi Town on the east coast of Toyama Bay (JMA, 2024). Based on these results and tsunami heights observed at tide stations, the maximum tsunami heights along the coast of Toyama Prefecture are generally 0.5 to just over 2 m.
3. Tsunami arrival time obtained from live camera analysis
We do not receive any eyewitness information that would lead to the exact arrival time of the tsunami because most of the respondents evacuated appropriately during the issuance of the tsunami warning. We extracted the polarity and arrival time of the initial tsunami wave from the observation data at each tide station along the coast of Toyama Bay: downward at about 4 min + OT at Ikuji, Kurobe City, and upward at about 3 min + OT at Fushiki-Toyama, Takaoka City. In addition, Minami et al. (2024, JpGU2024 HDS11-11) extracted tsunami time series waveforms by analyzing live camera movies recorded by broadcasting companies from fixed viewpoints. The polarity and arrival time of the initial tsunami wave at the Amaharashi coast, Takaoka City, were upward at about 7 min + OT. As described above, we confirmed that tsunamis arrived early (3–7 min + OT) at various points along the coast of Toyama Bay.
4. Conclusion
The early-arriving tsunamis are confirmed along the Toyama Bay coast at locations other than the Toyama Tide Station. The maximum tsunami heights along the Toyama Bay coast are generally 0.5 to just over 2 m. These results will provide important constraints for the detailed estimation of tsunami sources in Toyama Bay due to the Noto Peninsula earthquake.
Acknowledgements:
Takaoka Cable Network Co. Ltd., and Cable Television Toyama Inc. provided live camera movies at Amaharashi Beach and Iwasehama, respectively. Observation data from tide stations operated by the Ports and Harbours Bureau, and the Water and Disaster Management Bureau were also used in this study. This research was partially supported by a Grant-in-Aid for Scientific Research (KAKENHI 23K17482).