5:15 PM - 6:30 PM
[HDS07-P01] Issues for long-term evaluation of Byobu-yama/Ena-san fault zone
Keywords:active fault, earthquake, long-term evaluation
Introduction
The Headquarters for Earthquake Research Promotion selected the northern part of the " Byobuyama/Enasann Fault and Sanageyama Fault" as the target of intensive research (2020-2022). The purpose of this survey is to improve active fault evaluation and strong motion evaluation. The research group led by Nagoya University summarized the problems of the conventional evaluation of the fault and formulated a research plan to improve them.
Issues and research objectives
The "Byobuyama/Enasann Fault and Sanageyama Fault" is a long active fault zone with a total length of over 100 km from the Ena Mountains through the Okazaki Plain to the Chita Peninsula. The faults that make up the fault zone are close to each other, and it is difficult to decide a source fault scenario. Around the fault, there are densely populated areas such as Nagoya City and industrially concentrated areas such as Toyota City.
In Japan, the survey on this fault zone was once carried out from 1995 to 2000, however the activity history and fault structure data are scarce. Based on such data, in the previous long-term evaluation, the Enasan-Sanageyama north fault zone was ranked A *, the Byobuyama fault and the Kagiya fault were ranked A, the Sanage-Takahama fault was ranked Z, and the Akagawa fault was ranked X. "Fault near Nagoya City" was unknown.
The conventional active fault evaluation has the following problems.
1) Comparing the active fault map of the Geographical Survey Institute (1996-2016), the detailed digital map of the active fault (2002), and the active fault map of Gifu Prefecture (2010), there is a difference in trace identification.
2) It is assumed that the Enasan fault and the Sanageyama north fault, which have different geometrical characteristics, activate together.
3) There is no specific activity history for the Byobuyama fault. Since the earthquake occurrence probability is calculated by the Poisson process model, it cannot be compared with the probability of other faults based on the renewal process model.
4) The northern part of the Sanage-Takahama fault zone is evaluated as Z rank in calculation, while it is assumed that the activity confirmed at one point is regarded as the latest activity and that the total length of 51 km causes a 4 m displacement.
The Headquarters for Earthquake Research Promotion selected the northern part of the " Byobuyama/Enasann Fault and Sanageyama Fault" as the target of intensive research (2020-2022). The purpose of this survey is to improve active fault evaluation and strong motion evaluation. The research group led by Nagoya University summarized the problems of the conventional evaluation of the fault and formulated a research plan to improve them.
Issues and research objectives
The "Byobuyama/Enasann Fault and Sanageyama Fault" is a long active fault zone with a total length of over 100 km from the Ena Mountains through the Okazaki Plain to the Chita Peninsula. The faults that make up the fault zone are close to each other, and it is difficult to decide a source fault scenario. Around the fault, there are densely populated areas such as Nagoya City and industrially concentrated areas such as Toyota City.
In Japan, the survey on this fault zone was once carried out from 1995 to 2000, however the activity history and fault structure data are scarce. Based on such data, in the previous long-term evaluation, the Enasan-Sanageyama north fault zone was ranked A *, the Byobuyama fault and the Kagiya fault were ranked A, the Sanage-Takahama fault was ranked Z, and the Akagawa fault was ranked X. "Fault near Nagoya City" was unknown.
The conventional active fault evaluation has the following problems.
1) Comparing the active fault map of the Geographical Survey Institute (1996-2016), the detailed digital map of the active fault (2002), and the active fault map of Gifu Prefecture (2010), there is a difference in trace identification.
2) It is assumed that the Enasan fault and the Sanageyama north fault, which have different geometrical characteristics, activate together.
3) There is no specific activity history for the Byobuyama fault. Since the earthquake occurrence probability is calculated by the Poisson process model, it cannot be compared with the probability of other faults based on the renewal process model.
4) The northern part of the Sanage-Takahama fault zone is evaluated as Z rank in calculation, while it is assumed that the activity confirmed at one point is regarded as the latest activity and that the total length of 51 km causes a 4 m displacement.