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[U15-P01] The 2024 Noto Peninsula Earthquake -Seismicity and Earthquake/Tsunami Information issued by JMA-
Keywords:The 2024 Noto Peninsula Earthquake, Seismicity, Tsunami, Strong ground motion
In the Noto region, Ishikawa Prefecture, the number of earthquakes is increasing since about 2018, and seismicity became more active since December 2020, and even more active since July 2021. A magnitude (M) 6.5 earthquake (maximum intensity 6 upper) occurred on May 5, 2023. The seismicity became more active since then, although the number of earthquakes had decreased by December 2023.
An M7.6 earthquake (maximum intensity 7: the highest intensity) occurred at 16:10 on January 1, 2024, at a depth of 16 km in the Noto region, Ishikawa Prefecture, with intensity 7 observed in Wajima City and Shika Town, Ishikawa Prefecture, and intensity from 6 upper to 1 mainly in the Hokuriku region and from Hokkaido to Kyushu regions. Long-period ground motion class 4 (the highest class) was observed in Noto, Ishikawa Prefecture, and long-period ground motion class 3 to 1 was observed mainly in the Hokuriku region, from the Tohoku region to the Chugoku and Shikoku regions. The Japan Meteorological Agency (JMA) issued an earthquake early warning at 16:10:16.0, 6.0 seconds after the first seismic wave was detected. JMA issued a tsunami warning for Niigata, Toyama, and Ishikawa Prefectures, and a tsunami advisory for the regions along the Japan Sea Coast, from the southern part of Hokkaido to Yamaguchi Prefecture at 16:12. At 16:22, a major tsunami warning was upgraded for Noto area, Ishikawa Prefecture, a tsunami warning was upgraded for Yamagata, Fukui, and the northern part of Hyogo Prefectures, and a tsunami advisory was additionally issued for the western parts of the Pacific Coast of Hokkaido, the northern part of the Japan Sea Coast of Hokkaido and the Japan Sea coast of the Kyushu region (lifted at 10:00 on the 2nd). The earthquake caused tsunamis to be observed over a wide area from Hokkaido to Kyushu, mainly along the Japan Sea Coast, including an 80 cm tsunami in Kanazawa, Ishikawa Prefecture, and a 0.8 m tsunami in Sakata, Yamagata Prefecture. Field investigations by JMA also revealed traces of tsunamis caused by the earthquake, including over 5 m (run-up height) in Joetsu City, Niigata Prefecture, and over 3 m (inundation height) in Suzu City and Noto Town, Ishikawa Prefecture. This earthquake occurred within the crust. The focal mechanism (CMT solution) showed a reverse fault type with a compression axis in an NW-SE direction. JMA has named the M7.6 earthquake that occurred in the Noto region, Ishikawa Prefecture on January 1, 2024, and a series of seismic activities since December 2020 as “The 2024 Noto Peninsula Earthquake”.
Just before the M7.6 earthquake, an M5.5 earthquake (maximum intensity 5 upper) occurred at 16:06 on the same day. After this earthquake, an M5.7 earthquake (maximum intensity 6 lower) occurred at 16:12, an M6.1 earthquake (maximum intensity 5 upper) at 16:18, an M4.3 earthquake (maximum intensity 6 lower) at 23:20 on the 6th, and an M6.1 earthquake (maximum intensity 5 lower) at 17:59 on the 9th, and high seismicity have continued. The length of high seismicity area since January 1 extends about 150 km in an NE-SW direction on the Noto Peninsula and the sea area northeast of the Noto Peninsula. In this area, about 1,800 earthquakes of intensity 1 or higher (maximum seismic intensity: number of earthquakes, 7: 1, 6 lower: 2, 5 upper: 8, 5 lower: 7) have occurred since 16:00, January 1, through the end of March. Since the occurrence of the M7.6 earthquake, JMA had issued at any time the perspective of seismic activity in accordance with the "Information on the Perspective of Seismic Activity after a Major Earthquake" published by the Earthquake Research Committee (2016). Within one week after the M7.6 earthquake, we alerted people to the possibility of an earthquake of similar magnitude based on past cases, and since one week after the M7.6 earthquake until the end of February, we alerted people periodically based on the probability of earthquake occurrence calculated by the combination of the Omori-Utsu Formula and Gutenberg-Richter Formula.
An M7.6 earthquake (maximum intensity 7: the highest intensity) occurred at 16:10 on January 1, 2024, at a depth of 16 km in the Noto region, Ishikawa Prefecture, with intensity 7 observed in Wajima City and Shika Town, Ishikawa Prefecture, and intensity from 6 upper to 1 mainly in the Hokuriku region and from Hokkaido to Kyushu regions. Long-period ground motion class 4 (the highest class) was observed in Noto, Ishikawa Prefecture, and long-period ground motion class 3 to 1 was observed mainly in the Hokuriku region, from the Tohoku region to the Chugoku and Shikoku regions. The Japan Meteorological Agency (JMA) issued an earthquake early warning at 16:10:16.0, 6.0 seconds after the first seismic wave was detected. JMA issued a tsunami warning for Niigata, Toyama, and Ishikawa Prefectures, and a tsunami advisory for the regions along the Japan Sea Coast, from the southern part of Hokkaido to Yamaguchi Prefecture at 16:12. At 16:22, a major tsunami warning was upgraded for Noto area, Ishikawa Prefecture, a tsunami warning was upgraded for Yamagata, Fukui, and the northern part of Hyogo Prefectures, and a tsunami advisory was additionally issued for the western parts of the Pacific Coast of Hokkaido, the northern part of the Japan Sea Coast of Hokkaido and the Japan Sea coast of the Kyushu region (lifted at 10:00 on the 2nd). The earthquake caused tsunamis to be observed over a wide area from Hokkaido to Kyushu, mainly along the Japan Sea Coast, including an 80 cm tsunami in Kanazawa, Ishikawa Prefecture, and a 0.8 m tsunami in Sakata, Yamagata Prefecture. Field investigations by JMA also revealed traces of tsunamis caused by the earthquake, including over 5 m (run-up height) in Joetsu City, Niigata Prefecture, and over 3 m (inundation height) in Suzu City and Noto Town, Ishikawa Prefecture. This earthquake occurred within the crust. The focal mechanism (CMT solution) showed a reverse fault type with a compression axis in an NW-SE direction. JMA has named the M7.6 earthquake that occurred in the Noto region, Ishikawa Prefecture on January 1, 2024, and a series of seismic activities since December 2020 as “The 2024 Noto Peninsula Earthquake”.
Just before the M7.6 earthquake, an M5.5 earthquake (maximum intensity 5 upper) occurred at 16:06 on the same day. After this earthquake, an M5.7 earthquake (maximum intensity 6 lower) occurred at 16:12, an M6.1 earthquake (maximum intensity 5 upper) at 16:18, an M4.3 earthquake (maximum intensity 6 lower) at 23:20 on the 6th, and an M6.1 earthquake (maximum intensity 5 lower) at 17:59 on the 9th, and high seismicity have continued. The length of high seismicity area since January 1 extends about 150 km in an NE-SW direction on the Noto Peninsula and the sea area northeast of the Noto Peninsula. In this area, about 1,800 earthquakes of intensity 1 or higher (maximum seismic intensity: number of earthquakes, 7: 1, 6 lower: 2, 5 upper: 8, 5 lower: 7) have occurred since 16:00, January 1, through the end of March. Since the occurrence of the M7.6 earthquake, JMA had issued at any time the perspective of seismic activity in accordance with the "Information on the Perspective of Seismic Activity after a Major Earthquake" published by the Earthquake Research Committee (2016). Within one week after the M7.6 earthquake, we alerted people to the possibility of an earthquake of similar magnitude based on past cases, and since one week after the M7.6 earthquake until the end of February, we alerted people periodically based on the probability of earthquake occurrence calculated by the combination of the Omori-Utsu Formula and Gutenberg-Richter Formula.