Evaluation study of fault activity on Shionohira and Kuruma Faults located at the border of Fukushima and Ibaraki Prefecture, Japan

Aoki, Kazuhiro; Imai, Hirotaro; Seshimo, Kazuyoshi; Kimura, Megumi; Kirita, Fumio; Nakanishi, Ryuji

JAEA-Research 2024-005, 177 Pages, 2024/10

JAEA-Research-2024-005.pdf:12.02MB

This study presents a method for evaluating displacements on active faults that lack clear markers of fault offset. The method uses geological surveys, core studies, and chemical analyses along with hydraulic and mechanical tests. We applied this method to three test sites along the Shionohira Fault (Shionohira and Betto sites) and the Kuruma Fault (Minakamikita site). Laboratory friction tests on the fault gouge using a variable-speed, rotating shear friction apparatus were conducted. The samples from the Shionohira and Betto sites showed velocity weakening or strengthening, but no velocity dependence was observed at the Minakamikita site. A small-scale test to induce fault slip was conducted using the SIMFIP method. At the Shionohira site, fault slip can be modeled as a Coulomb rupture and shows a frictional dependence on slip velocity. On the other hand, at the Minakamikita site, a complex response using multiple fractures and slip planes was observed. Based on the water pressure response, the hydraulic properties of the area between the faults were evaluated. The transmissivity and specific storage are larger at Shionohira than at Minakamikita. Fault slip data such as shear plane attitude or shear sense were obtained from core samples and stress inversion analysis was performed. We attempted to elucidate the history of the movement and stress that formed the fracture zone. The results reconstructed five activity stages at Shionohira site and two stages at Minakamikita site. As shown in this report, the frictional properties, fault rupture mode, hydraulic properties and the history of fault motion were found to be different between the Shionohira and Kuruma sites. However, the results are based on a few locational data, so case studies at other sites and more applications to other faults should be considered to improve the reliability of the evaluation.

Seismic transient change of natural frequency estimation by adaptive filtering scheme

Kirita, Fumio; Kanazawa, Kenji*; Kitamura, Haruyuki*

Proceedings of 14th World Conference on Earthquake Engineering (WCEE-14) (CD-ROM), 8 Pages, 2008/10

This paper presents a new system identification procedure for a time-varying system to estimate natural frequency transition of a building from a strong seismic motion record, named as "Adaptive Forward-Backward Kalman Filter (AFB-KF)". The AFB-KF is compared to the conventional Kalman Filter in the below three points: (1) Forgetting factor for covariance functions to track time-varying structural parameters rapidly, (2) Time-backward estimation scheme and global iteration scheme of the forward and backward processes to estimate unknown initial value of structural parameters, (3) The time series renewal algorithm of statistical properties by reflecting the previous analysis information to improve the identification accuracy. It is useful to accurately identify from natural frequency transition of a building during an earthquake for structural health monitoring which evaluates structural integrity.

Long-term monitoring of natural frequencies of a full-scale 4-story building E-defense experimental projects for steel buildings

Kirita, Fumio

no journal, , 

no abstracts in English

Numerical simulation of long-period ground motion generated from intraplate earthquakes around Ibaraki and Fukushima prefectures, 2

Fujihara, Satoru*; Kirita, Fumio; Kawaji, Kaoru*; Yamazaki, Toshihiko; Uryu, Mitsuru

no journal, , 

no abstracts in English

A Study on the response characteristics of base-isolated structures for earthquake motion, 2

Nakanishi, Ryuji; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Kirita, Fumio; Kojima, Keidai

no journal, , 

no abstracts in English

Performance evaluation of lead dampers on base-isolated building attacked by the 2011 off the Pacific coast of Tohoku earthquake, 1

Hashimura, Hirohiko; Uryu, Mitsuru; Yamazaki, Toshihiko; Nakanishi, Ryuji; Kirita, Fumio; Kojima, Keidai

no journal, , 

no abstracts in English

Performance evaluation of lead dampers on base-isolated building attacked by the 2011 off the Pacific coast of Tohoku earthquake, 3

Kojima, Keidai; Uryu, Mitsuru; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kirita, Fumio

no journal, , 

no abstracts in English

Performance evaluation of lead dampers on base-isolated building attacked by the 2011 off the Pacific coast of Tohoku earthquake, 5

Uryu, Mitsuru; Kirita, Fumio; Yamazaki, Toshihiko; Hashimura, Hirohiko; Nakanishi, Ryuji; Kojima, Keidai

no journal, , 

no abstracts in English

Evaluation of long-period ground motion in northern Ibaraki coastal areas on earthquake occurred in the border of Fukushima-Ibaraki prefectures, 1

Yasuda, Masahiro; Uryu, Mitsuru; Yamazaki, Toshihiko; Kirita, Fumio; Fujihara, Satoru*; Kawaji, Kaoru*

no journal, , 

no abstracts in English

Evaluation of long-period ground motion generated from intraplate earthquakes around Ibaraki and Fukushima prefectures

Fujihara, Satoru*; Kirita, Fumio; Kawaji, Kaoru*; Yamazaki, Toshihiko; Uryu, Mitsuru; Yasuda, Masahiro

no journal, , 

no abstracts in English