[M-IS17] History X Earth and Planetary Science

[MIS17-P03] Damage and number of felt earthquakes of the 1729 Noto Peninsula earthquake

*Yasuyuki Kano^1,2, Masaharu Ebara³, Kenji Satake^1,2 (1.Earthquake Research Institute, The University of Tokyo, 2.Collaborative Research Organization for Historical Materials on Earthquakes and Volcanoes, The University of Tokyo, 3.Association for the Development of Earthquake Prediction)

Keywords:Noto Peninsula Earthquake, Historical earthquake

In the Noto Peninsula and its vicinity, including the epicentral area of the 2024 Noto Peninsula Earthquake, earthquakes have frequently occurred throughout historical times. There are records describing the effects of the quake, such as house collapses and landslides, as well as subsequent seismic activities of the earthquake occurred on August 1, 1729. The magnitude of the earthquake is estimated to be around M6.6 to 7.0. According to "Shinnen-ji Kiseki-cho" (Yanagida, Noto Town) and the "Juuzou-gu Houka-cho" (Wajima City), earthquakes were felt around noon, with the third occurrence in the evening being particularly significant. Other historical records also mention two large earthquakes on August 1, among multiple seismic events on that day. Earthquake occurrences, or felt record numbers, were extracted at (a) Yanagida, Noto Town ("Shinnen-ji Kiseki-cho" and "Yanagida Village History"), (b) Nakai, Anamizu Town ("Kaga Han Kiji Ruihen" and "Suge-ke Kenmon-shu"), (c) Wajima City ("Juuzou-gu Houka-cho"), and (d) Wajima City ("Kaga Han Kiji Ruihen" and "Suge-ke Kenmon-shu"). In cases where records indicate 6 to 7 occurrences, the higher number was considered. Qualitative description such as "throughout the day" and the number of occurrences over a certain period were converted to a per-day frequency. According to the "Juuzou-gu Houka-cho," Wajima City experienced earthquakes 4 to 7 times daily, while records from "Kaga Han Kiji Ruihen" mention approximately 100 times over 1 to 12 days. As mentioned in previous studies, felt aftershocks continued for two weeks following the earthquake. According to the "Juuzou-gu Houka-cho," there were no noticeable earthquakes in Wajima after August 15, 1729. Another earthquake of magnitude 5.7 occurred on April 2, 1896 (29th year of the Meiji era). According to the Central Meteorological Observatory's "Investigation Ledger," earthquakes were observed in Suzu (Iida and Oosaki Village) for about a week. While indications of uplift on the northern coast of the Noto Peninsula following the 1729 earthquake are reported, no historical records supporting this have been found. Additionally, previously unpublished earthquake descriptions not included in existing earthquake historical data compilations have been discovered. Understanding the recurring large earthquakes in the Noto Peninsula and the characteristics of smaller earthquakes with higher frequency, such as the 1729 event, through historical records is essential. Acknowledgment: Geoshape repository by ROIS-DS CODH are used to obtain latitude and longitude of the data points.