Analysis of the stress field around concealed active fault from minor faults-slip data collected by geological survey; An Example in the 1984 Western Nagano Earthquake region

Nishiyama, Nariaki; Nakajima, Toru; Goto, Akira*; Hakoiwa, Hiroaki; Nagata, Mitsuhiro; Shimada, Koji; Niwa, Masakazu

Earth and Space Science (Internet), 11(6), p.e2023EA003360_1 - e2023EA003360_15, 2024/06

https://doi.org/10.1029/2023EA003360

Earthquakes with magnitudes of 6-7 have been reported even in various active tectonic settings where fault deformation topography have not been detected. Therefore, delineating concealed active faults generating such earthquakes is necessary to reduce earthquake damage; however, few studies exist to provide its clues regarding such faults. The 1984 Western Nagano Earthquake in Japan was a main shock with a magnitude of Mj 6.8 and a depth of 2 km at the source. Solid bedrocks are well-exposed in the earthquake source region; however, no surface rupture have been identified, and the active fault is known to be concealed. In this study, we collected data on striations observed in fractures by geological survey around the source area of the 1984 Western Nagano Earthquake. Using the collected data, the multiple inverse method was used to estimate the stresses that affected the striation formation. Consequently, stresses similar to acting faults in this area were detected in minor faults around the known concealed active fault. This suggests that the minor faults might be part of the damage zone that has been developed around the concealed active fault. Some minor faults were recognized in Quaternary volcanic rocks, confirming that they experienced displacements recently. This study indicates the possibility of detecting concealed active faults in the bedrock by geological survey.

Gas Permeability in Graphite used in Seal Performance Test for the Experimental VHTR Core

; Takizuka, Takakazu;

JAERI-M 84-234, 42 Pages, 1985/01

JAERI-M-84-234.pdf:1.62MB

no abstracts in English

Theoretical study for accelerated two-phase flow, 1; Constant-area flow

Bull.JSME, 23(178), p.536 - 544, 1980/00

http://ci.nii.ac.jp/naid/110002359226

no abstracts in English

An Analysis of CSNI Standard Problem No.6 by ALARM-B1 Computer Code

JAERI-M 8483, 74 Pages, 1979/10

JAERI-M-8483.pdf:1.57MB

no abstracts in English

Theoretical analysis for accelerated two-phase flow, 1; Flow in constant-area

Nihon Kikai Gakkai Rombunshu, B, 45(396), p.1169 - 1178, 1979/00

https://doi.org/10.1299/kikaib.45.1169

no abstracts in English

Frictional energy dissiparion in two-Phase Flow

;

Nihon Genshiryoku Gakkai-Shi, 18(12), p.786 - 795, 1976/12

https://doi.org/10.3327/jaesj.18.786

no abstracts in English