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.

Fission-track ages of late Pliocene to Pleistocene strata around the eastern margin of the Yokote Basin active fault zone, northeast Japan

Kosaka, Hideki*; Kagohara, Kyoko; Miwa, Atsushi*; Imaizumi, Toshifumi*; Kurosawa, Hideki; Nohara, Tsuyoshi

Chigaku Zasshi, 117(5), p.851 - 862, 2008/10

https://doi.org/10.5026/jgeography.117.851

To understand the development process of the fault zone, fission-track ages of rocks and rock facies are investigated in western margin of the Ou Backbone Range of Northeast Japan. Fission-track dating was carried out for 5 acid volcanic rocks from the late Pliocene to Pleistocene strata which were deposit associated with mountain belt growth. Statistically significant ages obtained are 1.50.1 Ma (OB-03) and 1.850.1 Ma (YG-01) for the Tazawa Formation, 1.60.3 Ma (FT-01) for the Kurisawa Formation,0.930.14 Ma (FT-02) and 2.70.3 Ma (FT-03) for the Senya Formation. According to the fission-track dating in this study, ages of the mountain belt growth with acid volcanic activity are estimated to before 1 Ma.

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.

Examination of H gas emission due to fault activity

Kurosawa, Hideki; Ishimaru, Tsuneari; Niwa, Masakazu; Shimada, Koji; Kagohara, Kyoko

no journal, , 

no abstracts in English

Examination of an investigation technique for activity on a fault-related fold in the Tenpoku region, northern Hokkaido, Japan

Nohara, Tsuyoshi; Kosaka, Hideki*; Kagohara, Kyoko*; Miwa, Atsushi*; Tokiwa, Tetsuya; Imaizumi, Toshifumi*

no journal, , 

Activity in the fault-related fold zone in the Tenpoku region, where the influence of the interplate coupling is comparatively small, has been investigated to explain the contradiction between geomorphological and geodetic information. Moreover, the actual average shortening rate of the Sarobetsu fault zone was investigated using the balanced cross section analytical method that used 2D Move. The results of this study show that the estimation of the long term crustal shortening rate in a fault-related fold zone, based on information from the geological structure, is important. In this study, it has been confirmed that information on the deformation of the geological structure is consistent to information on the tectonic landform. A multiple lines of evidence approach, including geomorphological, geological and geodetic investigation methods, will reduce uncertainty related to the average shortening rate along the fault of the fault-related fold.

Significance of exposure of the Taie Fault at Sugisaki, central Japan, 1

Kagohara, Kyoko; Kurosawa, Hideki; Kosaka, Hideki*; Ishimaru, Tsuneari

no journal, , 

no abstracts in English

Hydrogen gas concentration dependent on the structure of fracture zones

Kurosawa, Hideki; Ishimaru, Tsuneari; Kagohara, Kyoko; Kosaka, Hideki*; Shimada, Koji

no journal, , 

no abstracts in English

Technique for underground survey on thrust fault zone

Kagohara, Kyoko; Kurosawa, Hideki; Ishimaru, Tsuneari; Nohara, Tsuyoshi

no journal, , 

Assessment of the effects of earthquakes and faulting on the deep geological environment is absolutely essential for site selection and design of high-level radioactive waste repositories in Japan. For thrust faults, there are widely deformations in strata or surface, complex geological structure caused by blind thrust, and lateral propagation and growth. Thus, it is important to understand the morphic character and history of thrust faults, based on the tectonic landforms and underground structures. Here, we presented the results of the case study at the Yokote basin fault zone that is a typical thrust fault of Japan. It reports on the relation between geographical features and underground structure of the Yokote basin fault zone.