Characterizing the reactivation mechanisms of coseismic surface ruptures associated with the 2011 Mw 6.7 Fukushima-ken Hamadori earthquake in Japan through borehole hydromechanical testing

Guglielmi, Y.*; Aoki, Kazuhiro; Cook, P.*; Soom, F.*; Cappa, F.*; Tanaka, Yukumo

Tectonophysics, 819, p.229084_1 - 229084_22, 2021/11

https://doi.org/10.1016/j.tecto.2021.229084

The reactivation mechanisms of coseismic surface ruptures associated with the 2011 Mw 6.7 Fukushima-ken Hamadori earthquake in Japan are investigated using in-situ controlled hydraulic injections in subsurface boreholes. Two fault segments were selected for reactivation studies, one across a coseismic rupture, the Shionohira site, and one across a non-coseismically ruptured segment, the Minakami-kita site. A series of water injections in sealed sections of boreholes set across the fault progressively bring the fault to rupture by a step-by-step decrease of the effective normal stress clamping the fault. While the fault is rupturing during these hydraulic stimulations, borehole displacements, fluid pressure and injection flowrate are continuously monitored. Then, the tests were analyzed using fully coupled hydromechanical modeling. The model was calibrated on field data, and a parametric study was conducted to examine the modes of fault reactivation. Coseismic surface rupture of the Shionohira fault showed a pure dilatant slip response to hydraulic tests, while the tectonically un-activated Itozawa fault (South) indicated a complex hybrid response to tests related to both a higher frictional and cohesive strengths of the fault. The analysis of the induced Shionohira slip event showed that it is reasonably modeled as a Coulomb rupture with an eventual dependency of friction on slip velocity, in good accordance with laboratory-derived rate-and-state friction data on the Shinohira gouge samples. In contrast, the Itozawa fault reactivation mechanism appears dominated by tensile failure with limited Coulomb shear failure. Thus, the applied protocol proves to be able to isolate significant differences in fault physical properties and rupture mechanisms between two segments of the same fault system, opening perspectives to better assess near-surface rupture effects, and therefore the safety of structures subject to large earthquakes.

Synchronized gravitational slope deformation and active faulting; A Case study on and around the Neodani fault, central Japan

Komura, Keitaro*; Kaneda, Heitaro*; Tanaka, Tomoki*; Kojima, Satoru*; Inoue, Tsutomu*; Nishio, Tomohiro

Geomorphology, 365, p.107214_1 - 107214_22, 2020/09

https://doi.org/10.1016/j.geomorph.2020.107214

On the basis of pit excavations and sediment cores at an off-fault deep-seated gravitational slope deformation (DGSD) site and a trench excavation across the active Neodani fault at a nearby site, we examined the records of DGSD and surface-rupturing paleoearthquakes of the Neodani fault. We found the four most recent DGSD events and the four most recent surface-rupturing earthquakes, respectively and conclude that the ages of events are overlapped each other. We infer that static crustal strain from repeated seismogenic faulting plays an important role in the occurrence of DGSD events, at least in the immediate vicinity of active faults, although coseismic severe shaking would have at least some effect on them. Our case study suggests that off-fault DGSDs can be used to reconstruct or refine the paleoseismic history of a nearby active fault.

Complete Ar resetting in an ultracataclasite by reactivation of a fossil seismogenic fault along the subducting plate interface in the Mugi Mlange of the Shimanto accretionary complex, southwest Japan

Tonai, Satoshi*; Ito, Shun*; Hashimoto, Yoshitaka*; Tamura, Hajimu; Tomioka, Naotaka*

Journal of Structural Geology, 89, p.19 - 29, 2016/08

https://doi.org/10.1016/j.jsg.2016.05.004

We used the K-Ar ages of clay-sized mineral grains to investigate the timing of activity on the fossil seismogenic Minami-Awa Fault. The K-Ar ages from matrix shale of the mlange range from 85 to 48 Ma and decrease with decreasing amount of detrital mica. In contrast, the K-Ar ages of an ultracataclasite within the fault core are significantly younger, ranging from 29 to 23 Ma, and are unrelated to grain size. This indicates that Ar diffused completely from the ultracataclasite between 29 and 23 Ma. The diffusion of Ar in the ultracataclasite was probably caused by frictional heating or high-temperature fluid migration that occurred when the fault was reactivated. The results indicate that seismogenic faults that separate tectonic mlange from coherent strata in accretionary complex may slip, not only during accretion, but also long after accretion.

Development of structural reliability evaluation method for aged piping considering uncertainty of seismic motions

Sugino, Hideharu*; Ito, Hiroto*; Onizawa, Kunio; Suzuki, Masahide

Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(4), p.233 - 241, 2005/12

https://doi.org/10.3327/taesj2002.4.233

The purpose of this research is to establish the reliability evaluation method of aged nuclear power components for seismic events from a viewpoint of long-term use of the existing light water reactor nuclear power plants. For this purpose, we developed a piping failure probability evaluation code "PASCAL-SC" based on probabilistic fracture mechanics, and a probabilistic seismic hazard evaluation code "SHEAT-FM" for calculating the seismic occurrence probability of a plant site, paying attention to aging such as fatigue crack progress by the stress corrosion cracking and seismic load in primary coolant piping system. We proposed the reliability evaluation method of aged piping for seismic events by combination of these codes. Using this method, we evaluated the reliability of a weld line in the PLR(Primary Loop Recirculation system) piping of the BWR model plant for seismic events.

SHEAT for PC: A Computer code for probabilistic seismic hazard analysis for personal computer, user's manual

Yamada, Hiroyuki; Tsutsumi, Hideaki*; Ebisawa, Katsumi*; Suzuki, Masahide

JAERI-Data/Code 2002-001, 161 Pages, 2002/03

JAERI-Data-Code-2002-001.pdf:6.62MB

no abstracts in English

Fault tree analysis of system anomaly leading to red oil explosion in plutonium evaporator

Nomura, Yasushi; R.Leicht*; P.Ashton*

Journal of Nuclear Science and Technology, 31(8), p.850 - 860, 1994/08

https://doi.org/10.3327/jnst.31.850

no abstracts in English

A Research on applications of qualitative reasoning techniques in Human Acts Simulation Program

B.H.Far*

JAERI-M 92-058, 79 Pages, 1992/04

JAERI-M-92-058.pdf:2.65MB

no abstracts in English

Observation of defect clusters in masked thin foil CU by He ion irradiation

*; *; *; ; ;

Proc.XIth Int.Cong.on Electron Microscopy, p.1281 - 1282, 1986/00

no abstracts in English

Effect of external stress on the microstructural change during electron-irradiation in nickel

; Katano, Y.; Shiraishi, K.

Journal of Nuclear Science and Technology, 21(9), p.671 - 677, 1984/00

https://doi.org/10.3327/jnst.21.671

no abstracts in English

Recent progress in safety-related applications of reactor noise analysis

; Shinohara, Yoshikuni; *; *; *; Nishihara, Hideaki*; *; *; Tamura, Seiji*; *

Nihon Genshiryoku Gakkai-Shi, 24(3), p.188 - 198, 1982/00

https://doi.org/10.3327/jaesj.24.188

no abstracts in English