Journal of the Geodetic Society of Japan
Online ISSN : 2185-517X
Print ISSN : 0038-0830
ISSN-L : 0038-0830
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Volume 49, Issue 4
Displaying 1-6 of 6 articles from this issue
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  • Crustal Strain Observation with a Laser Extensometer in a Shallow Tunnel
    Shuzo Takemoto, Hideo Momose, Kunio Fujimori, Toshihiro Higashi
    2003 Volume 49 Issue 4 Pages 215-225
    Published: December 25, 2003
    Released on J-STAGE: September 07, 2010
    DOIhttps://doi.org/10.11366/sokuchi1954.49.215
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    A laser extensometer was installed in a shallow observation room at Kwasan Astronomical Observatory, Graduate School of Science, Kyoto University in 1999. Since then, we have carried on precise observation of crustal strains with the laser extensometer. The purpose of this paper is to estimate the effect of meteorological changes (e.g. ambient temperature change, atmospheric pressure change, etc.) upon observation of crustal strains using a laser extensometer installed in a shallow tunnel. Results obtained are as follows; (1) Before closing the vacuum valve of the stainless steel pipe covering the light path of the laser interferometer, the strain data obtained from the laser extensometer showed significant influence of the atmospheric pressure change of 2.6×10-7/hPa. This can be explained by the refractive index change in the light path caused by atmospheric pressure change. (2) After evacuating the air in the light path and closing the vacuum valve, long-term strain changes corresponding to ambient temperature changes were observed in the order of 1×10-5/K. These changes can be fully explained by the thermal expansion coefficient of bedrock around the observation room, because linear thermal expansion of bedrock consisting of weathered granite is estimated to be (0.4-1.0)×10-5/K. (3) We then performed tidal analysis by applying FFT and BAYTAPG programs to one-year strain data obtained from the laser extensometer. As a result, there exist significant discrepancies between the observed and the calculated tidal amplitudes. The discrepancy is caused by non-sinusoidal daily temperature changes around the observation site due to sunshine from the east direction in the morning.
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  • Temporal Variations of Tidal Constituents in Strainmeter Records Prior to the Occurrence of Two Large Earthquakes
    Issei Hirose, Ichiro Kawasaki, Shuzo Takemoto, Yoshiaki Tamura
    2003 Volume 49 Issue 4 Pages 227-242
    Published: December 25, 2003
    Released on J-STAGE: September 07, 2010
    DOIhttps://doi.org/10.11366/sokuchi1954.49.227
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    We search for temporal variations of principal tidal constituents in strainmeter records, for instruments which are closely located to the source regions of large earthquakes in Japan. To obtain temporal variations, we apply the BAYTAP-G (Bayesian Tidal Analysis Program- Grouping Model) to data sets of 30 day lengths with time lags of 1 day. For the 01 constituent of the laser strainmeter record at the Rokko-Takao station, characteristic changes are observed in its amplitude-phase diagram a few years prior to the 1995 Kobe Earthquake (Mw6.9). Although the observed values are narrowly distributed in the amplitude-phase diagram before 1992, they become broader and a doughnut-pattern appears prior to the occurrence of the earthquake. For the case of the 1994 Far Off Sanriku Earthquake (Mw7.7), the same pattern is also noted at the Esashi station. There are no similar significant patterns in the M 2 constituent. Temporal correlation with the changes of b-values and micro-earthquake seismicity are also suggeste.
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  • Resultants Approach to the Triple Three-dimensional Intersection Problem
    Joseph L. Awange, Yoichi Eukuda, Shuzo Takemoto, Erik W Grafarend
    2003 Volume 49 Issue 4 Pages 243-256
    Published: December 25, 2003
    Released on J-STAGE: July 05, 2011
    DOIhttps://doi.org/10.11366/sokuchi1954.49.243
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    The resultant algebraic approach is here applied to solve the triple three-dimensional intersection problem vital in Photogrammetry and Computer vision. From the observations of type horizontal directions T and vertical directions Bi, with i = 1, 2, 3, we demonstrate that the three nonlinear system of equations can be decomposed using Strumfel's resultant method to three quartic polynomials whose roots are obtainable via MA TLAB-solve command. The advantage here is that when one is faced with the minimum number of known points, here three, one can still carry out an intersection to obtain the coordinates of the desired point. In Photo-grammetry, the procedure could be used to obtain the coordinates of pass points where known stations are limited only to the minimum number.
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  • Geodetic Survey of Japan in the Past 50 Years
    Minoru Tajima
    2003 Volume 49 Issue 4 Pages 257-263
    Published: December 25, 2003
    Released on J-STAGE: September 07, 2010
    DOIhttps://doi.org/10.11366/sokuchi1954.49.257
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  • Evolution of Geodetic Research Seen in the Session Programs of the Past Meetings of the Geodetic Society of Japan
    Yukio Hagiwara
    2003 Volume 49 Issue 4 Pages 265-268
    Published: December 25, 2003
    Released on J-STAGE: September 07, 2010
    DOIhttps://doi.org/10.11366/sokuchi1954.49.265
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  • A Report of the XXIII General Assemblies of IUGG and IAG in Sapporo
    Shuzo Takemoto, Hiromichi Tsuji, Yoichi Fukuda, Yuki Kuroishi, Peilian ...
    2003 Volume 49 Issue 4 Pages 269-287
    Published: December 25, 2003
    Released on J-STAGE: September 07, 2010
    DOIhttps://doi.org/10.11366/sokuchi1954.49.269
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