Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
Volume 33, Issue 4
Displaying 1-6 of 6 articles from this issue
  • Implications of Hanaore-Kongo Fault and Tsurugawan-Isewan Tectonic Lines
    Yuji KANAORI, Shin-ichi KAWAKAMI, Kenji YAIRI
    1992 Volume 33 Issue 4 Pages 187-201
    Published: October 10, 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Dating back to 599 A. D., 26 destructive earthquakes of magnitude 6.4 or greater in the Kinki district of central Japan have been documented. A number of extensively developed active faults have been found in the Kinki district. Two major tectonic lines, the Hanaore-Kongo fault line (HKFL) and Tsurugawan-Isewan tectonic line (TITL), can be identified as lines linking these active faults. The region north of the Median Tectonic Line, occupying the area between the two tectonic lines is defined as the intra-Kinki triangle (IKTA), where N-S aligned mountain ranges are separated by basins, forming a basin/range province. Steeply dipping reverse faults separate the mountain ranges from the basins. Since it was found that the epicenters of most of the destructive earthquakes were located along the two major tectonic lines, these earthquakes were probably caused by the movement of active faults which constitute the tectonic lines.
    The average rate re of the seismic moments released by the destructive earthquakes was compared with the average rate rs calculated from average slip rates of the active faults constituting the HKFL, TITL and IKTA. The average rates rs of the HKFL, TITL and IKTA were found to be in good agreement with the corresponding values of of re. The values of rs and re for the HKFL and TITL range from 0.015 to 0.030×1026 dyne-cm/yr, and are significantly greater than those of the IKTA, that is, 0.001 to 0.004×1026 dyne-cm/yr. These results imply that the seismic moments were mainly released along the tectonic lines.
    The examination of space-time distribution patterns of the destructive earthquakes clarified that active periods of seismic activity cyclically occurred on the HKFL and TITL. A scary earthquake of magnitude 7.5 or 7.4 was generated on the HKFL at the end of one such active period. When fault activity covers the entire length of a tectonic line, the active period ends. The HKFL and TITL are presently in the active periods, since three seismic gaps over which no destructive earthquakes have been detected during the present active period. One gap is on the TITL while the other two are located on the HKFL. Using the average rates re of seismic moment release of the tectonic lines, dates of earthquake generation are tentatively predicted for seismic gaps.
    Download PDF (2717K)
  • Oumai TSUJI, Yoji ISHIJIMA
    1992 Volume 33 Issue 4 Pages 202-211
    Published: October 10, 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    To investigate the fracture process and to interprete the strength parameters of the homogeneous soft rock mass obtained by the in-situ block shear test, two dimensional finite element simulation study has been conducted under the assumption that the rock mass behaves as the strain softening material. At the same time, three dimensional physical model experiment has been performed using plaster as the modeling material. Main results are as follows:
    (1) Results of the in-situ shear test obtained both by the simulation and model study were expressed as the linear curve in the σ-τdiagram, and the value of the shear strength indicated from these data lay between the peak shear strength and the residual shear strength esitimated from the triaxial tests.
    (2) In the model study, three types of shape on the shear load versus vertical displacement curve, depending on the vertical stress level, were recognized.
    (3) In the simulation study, progressive failure has started from the early stage of loading and in accordance with this, load-displacement curve bent from the straight line observed in the inital loading stage. Similar tendency for the corresponding curve was recognized both in the field tests and in the model study.
    (4) The corrugated shaped fracture surface located deeper than the assumed shear plane was observed in the field experiment as well as in the model study. It was also found in the model and in the simulation study that the thickness of the yield zone developing under the fracture surface was not uniform.
    Download PDF (1596K)
  • Part 1: The Devision of the Objective Area into the Modelling Areas and the Division of a Joint System into Joint Sets
    Kokichi KIKUCHI, Yoshitada MITO, Makoto HONDA
    1992 Volume 33 Issue 4 Pages 212-219
    Published: October 10, 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Generally, even if joint distribution has a regularity, the regularity is not uniform from the view of wide area. In order to generate the rock joint disutribution-model, therefore, it is necessary to classify previously the survey area into regions for which statistical properties of distribution characteristics are similar as much as possible. The authors suggest such area-division method in this paper
    Furthermore, a joint system is composed of several joint sets, and each joint set has its own distributional character. In this paper the authors also suggest the division method of joint system into several joint sets.
    Download PDF (1442K)
  • Akira IWAMATSU
    1992 Volume 33 Issue 4 Pages 220-226
    Published: October 10, 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Download PDF (1326K)
  • Shigeru NAGAI
    1992 Volume 33 Issue 4 Pages 227-236
    Published: October 10, 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Download PDF (1309K)
  • 1992 Volume 33 Issue 4 Pages 241
    Published: 1992
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Download PDF (88K)
feedback
Top