A Catalog showing distribution and features of lineaments and related landforms in an active shear zone with unclear fault displacement topography; An Example of an active left-lateral shear zone in southern Kyushu Island, southwest Japan (Contract research)

Goto, Akira; Sasaki, Akimichi*; Komatsu, Tetsuya; Miwa, Atsushi*; Terusawa, Shuji*; Kagohara, Kyoko*; Shimada, Koji

JAEA-Research 2020-013, 88 Pages, 2020/11

JAEA-Research-2020-013.pdf:22.86MB
JAEA-Research-2020-013-appendix(CD-ROM).zip:0.18MB

Improvement of the investigation techniques to identify active faults is important for the implementation of geological disposal projects from the viewpoint of avoiding locations where permeability increases due to fault displacement. Generally, the existence of active faults is confirmed by aerial photography interpretation of fault displacement topography, which is a topographical trace of fault movement, and on-site geological surveys. However, the investigation method for cases where the topographical traces are unclear is not sufficiently developed. Therefore, to improve existing topographical methods, this study deciphered lineaments up to the rank of poorly defined features, which are almost neglected in general active fault research. The investigation area is one of the geodetic strain concentration zone, called the southern Kyushu shear zone, where the seismogenic faults of the 1997 Kagoshima northwest earthquakes are concealed. We conducted aerial photography interpretation of 62 sheets of 1/25,000 topographic maps, and obtained 1,327 lineaments. Distribution density, direction and length of lineaments were also investigated with topographic and geologic information. As a result, it was clarified that the east-west lineaments in the south Kyushu shear zone predominate in the western part, and the lineaments are densely distributed in the aftershock distribution area of the Kagoshima northwest earthquake. Along with these results, we have compiled a catalog of typical 13 lineaments based on combinations of clarity, direction, length and geomorphic characters of lineaments.

Subsurface geometry and structural evolution of the eastern margin fault zone of the Yokote basin based on seismic reflection data, northeast Japan

Kagohara, Kyoko; Ishiyama, Tatsuya*; Imaizumi, Toshifumi*; Miyauchi, Takahiro*; Sato, Hiroshi*; Matsuta, Nobuhisa*; Miwa, Atsushi*; Ikawa, Takeshi*

Tectonophysics, 470(3-4), p.319 - 328, 2009/05

https://doi.org/10.1016/j.tecto.2009.02.007

Seismic reflection profiles across coseismic fault scarps of the A.D. 1896 Rikuu earthquake along the eastern margin of the Yokote basin fault zone (EYBFZ), correlated with borehole stratigraphy and geologic mapping, provide insights into its detailed structural evolution. In spite of along-strike variations of thrust geometries both at ground surface and at shallow depth, the EYBFZ has commonly formed as forward breaking imbricate thrust systems. Spatial variations in the long-term uplift rates estimated from cross-section balancing are consistent with mountain topography, in contrast to their weak coupling with the magnitudes of short-term uplift rates and coseismic uplift during the A.D. 1896 earthquake. This suggests that mechanical decoupling of Miocene mudstone that formed frontal emergent thrust faults may have enhanced the slip at shallowest structural levels at shorter timescales.

Crush zone structure in a compressional step; An Example of the western part of the Atotsugawa Fault, Hida City, Gifu Prefecture of Japan

Niwa, Masakazu; Shimada, Koji; Kurosawa, Hideki; Miwa, Atsushi*

Chishitsugaku Zasshi, 114(10), p.495 - 515, 2008/10

https://doi.org/10.5575/geosoc.114.495

This paper provides a geological description of crush zones in the western part of the active Atotsugawa Fault, Gifu Prefecture of Japan, to understand crush zone structures in steps of strike-slip faults. By means of aerial photograph interpretation, we recognized that the occurrence of a step is suggestive in the Sangawara area, and that a long strand of the Atotsugawa Fault with ENE-WSW trend is traced in the Itani Area. On the Basis of the detailed geological observation, attitude and sense of shear planes, and thickness and clay mineral composition of fault gouge are different between crush zones of the Sangawara and Itani areas. In the Sangawara area, shear planes with NNE-SSW and NW-SE strikes, high-angle oblique to the trend of the Atotsugawa Fault, are characteristically developed. These shear planes can be a part of the composite planar fabric such as R2 surfaces which are dominantly developed within compressional steps.

Active tectonics of the Senya Hills and evolution of the Senya Active Fault, Eastern margin of the Yokote Basin Fault Zone, Northeast Japan

Kagohara, Kyoko*; Imaizumi, Toshifumi*; Miyauchi, Takahiro*; Sato, Hiroshi*; Uchida, Takuma*; Echigo, Tomoo*; Ishiyama, Tatsuya*; Matsuta, Nobuhisa*; Okada, Shinsuke*; Ikeda, Yasutaka*; et al.

Chigaku Zasshi, 115(6), p.691 - 714, 2006/12

https://doi.org/10.5026/jgeography.115.6_691

The eastern marginal fault zone of the Yokote Basin is one of seismogenic reverse faults developed in Northeast Japan, generating the 1896 Riku-u Earthquake (M7.2). We discussed the relationship among fault traces, geomorphic displacements and fault geometries on the Senya fault, based on a data from high-resolution seismic reflection profiling, investigations in tectonic geomorphology and structural geology, with the help of the balanced cross section method. By the restoring the balanced cross sections, the horizontal shortening amount is estimated to be totally 3 km through the thrust system, and the thrusting is retroactive to 2.4 Ma. Depending on the strike of fault traces and the morphotectonic features, the Senya fault is subdivided into three, the northern, central and southern portion. The initiation of thrust front migration is ca.1.6 Ma at the central portion and 0.6 Ma at the northern portion. This means that the central portion preceded the northern portion as an emergent fault, and suggests that the initial propagated fault extends from the fault end to the boundary fault.

Investigation about long-term change of the water vein geological structure of the focus dislocation circumference

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-122, 176 Pages, 2004/03

JNC-TJ7420-2005-122.pdf:54.84MB

In this study, we have investigated around the earthquake source fault of the Western Tottori Prefecture Earthquake 2000 in order to presume a long-term change of the groundwater structure.

Beam-palarization asymmetries for the (,) and (,) reactions for =1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

https://doi.org/10.1103/PhysRevLett.91.092001

no abstracts in English

Groundwater behavior around of The Western Tottori prefecture Earthquake Source Fault in 2000

Miwa, Atsushi*; Kurosawa, Hideki*

JNC TJ7420 2005-121, 81 Pages, 2003/03

Drastic water level changes in wells near the epicenter were often observed with comparatively large inland earthquakes. Some mechanisms of the co-seismic groundwater level changes were reported. Rojstaczer, (1992) suggested that the earthquake increased rock permeability and temporarily enhanced ground-water flow rates. Sibson (1992) suggested that increase of the crustal strain causes the increase in pore water pressure. In this study, we have investigated the groundwater behaviors in and around the earthquake Source Fault of the Western Tottori prefecture earthquake 2000 by interview and analysis of observed values of the ground water level and of river level.

The Research of chemical composition in the rock near the fault

Miwa, Atsushi*; Kurosawa, Hideki*; Ichikawa, Yasuo*

JNC TJ7420 2005-097, 60 Pages, 2002/03

JNC-TJ7420-2005-097.pdf:18.2MB

Macro- and microscopic structures of the fault rocks included in the core from the 389.52m borehole across the Nojima Fault are described to show the groundwater flow model around the underground fracture zone.

None

Miwa, Atsushi*; Takahashi, Nao*

JNC TJ7420 2005-065, 153 Pages, 2001/03

no abstracts in English

Distribution of active faults

Miwa, Atsushi*; Sasaki, Tatsuya*; Takahashi, Nao*

JNC TJ7420 2005-027, 334 Pages, 2000/03

JNC-TJ7420-2005-027.pdf:53.45MB

It is important study to seize fault activity in order to clarify how effects the active faults influence geo-environment. In this paper, we investigated the distributive character and the activity of active faults with precise aerial photograph interpretation of tectonic landforms. And we prepared fault parameters for this new data by compiling previous results. A number of active faults exist particularly in central Japan. There is a marked regularity in the fault systems between the trend of faults and the sense of the displacement: the reverse fault system distributes in the Northeast Japan with NS-trending, the lateral faults distribute in the Southwest Japan. In particular, NW-trending faults are left-lateral, whereas NE-trending faults are right-lateral. Normal faults are in the central Kyusyu. This implies that the earth's crust of the region is under the same stress system having the maximum principal axis of approximate east-west. Activity of most of the active faults in Japan is class B(10-4 meters per one year). It is limited the distribution of active faults of class A. We presumed when active faults started to move from fault parameters. Active faults in Japan have started at least through a few hundreds thousand years ago.