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Volume 39 (1993)
- Issue 4 Pages 327-
- Issue 3 Pages 263-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 39, Issue 3
Displaying 1-8 of 8 articles from this issue
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Toshiya Sato, Satoshi Miura, Kenji Tachibana1993 Volume 39 Issue 3 Pages 263-274
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe Geographical Survey Institute has repeated the first order triangulations and trilaterations with high precision and high density since Meiji era in Japan . Many studies have been done in regard to horizontal strains of the crust by using these data. In those papers, they assume homogeneous strain fields in each triangle formed by three neighbouring triangulation stations. As a result, these triangles produce apparently discontinuous strain fields and are not convenient to elucidate spatial patterns and regional features. In this paper, we present a method to obtain continuous distributions of horizontal displacements and strains of the crust by means of triangulation and trilateration data in order to compare with other geophysical data sets. Weemploy two-dimensional Chebychev polynomials to interpolate horizontal displacements and strains at regularly distributed grid points. We applied the method for the first order triangulation and trilateration data in two regions in Japan to clearly reveal the regional features.View full abstractDownload PDF (5053K) -
Katsumi Nakane1993 Volume 39 Issue 3 Pages 275-281
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe differences between side lengths derived by the projection method and the development method are calculated to estimate the effect of deflections of the vertical on side length of the first order triangulation network of Japan. Better than 99% of side length differences of the net do not exceed 5 ppm. This means that the effect of deflections of the vertical on the side length is negligible in the first order triangulation network of Japan. Deflections of the vertical are precisely estimated at every first order triangulation station of Japan. In this precise estimation, topographic masses are computationally removed to eliminate the interpolation error due to the effect of the topographic irregularity. The accuracy of estimated deflections of the vertical is better than 3 seconds.View full abstractDownload PDF (612K) -
(An Attempt to Study Historical Earthquakes Through Fault Model)Zhang Tongyao, Hiroshi Sato1993 Volume 39 Issue 3 Pages 283-292
Published: September 25, 1993
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSA static fault model of the historical earthquake, the Noshiro-Tsugaru earthquake of 1704, has been studied. The quake occurred along the Japan sea coast of northeast district, Honshu Japan, where many damaging earthquakes took place during the period from the 17th to 19th century, and some of those quakes left the traces of coastal up lift. These traces have been investigated in detail by seismologists and geologists. Using these data, we attempt to study historical earthquakes through static fault model. The problem of such study is that sufficient data for modeling are generally not avail able. To overcome this problem, a similarity law between fault parameters, seismo tectonics in the area and theory of rock fracture are used. To check the pertinence of the model, seismic-moment and stress-drop are calculated from the obtained fault parameters, and these values are ascertained to be reasonable from the view point of seismology.View full abstractDownload PDF (1106K) -
Ping Shi, Jiro Segawa, Yoichi Fukuda1993 Volume 39 Issue 3 Pages 293-311
Published: September 25, 1993
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThis paper deals with the atmospheric effects involved in the time variations of grav ity measured by asuperconducting gravimeter. The atmospheric effects on the gravity changes are two-fold, i.e., the effect from the Newtonian attraction caused by the mass of the atmosphere and that from the loading effect caused by the deformation and density change of the Earth. The former effect was evaluated by assuming that the density change of the atmosphere with altitude follows an exponential function. The latter effect was evaluated using Farrell's Green function. One problem is that there is a singular point in the Green's functions of both effects at the angular distance ψ=0 measured from the gravimeter site. However, we proved that the both gravity changes converge at ψ=0. We obtained a closed formula for the Newtonian attraction, and a linear asymptotic solution for the loading effect. The total atmospheric effect thus ob tained is about 12 Fugal: Its 90% is caused by the atmosphere between ψ=0 and 0°43, the effect from the atmosphere between 0°43 and 2°7 is zero in all because the two effects cancel one another, and the global effect from outside ψ=2°7 is about 1 Fugal. Our superconducting gravimeter is installed at the past geophysical facility attached to the Faculty of Sciences, University of Tokyo, located at Kakioka, Ibaragi Prefecture (36°D233 N, 140°183 E, Elevation 31.7 m). The data used for evaluating the atmospheric effects are the pressure at the gravimeter site at the interval of 30 minutes, the local pressure data reported by the Japan Meteorological Agency, at the interval of 3 hours, and the global data distributed by the same agency at the interval of 24 hours. In this study the gravity data for one month in January 1990 were processed and corrected for the atmospheric effects. The result shows that the residual gravity change after corrections were made is 1 μgal in amplitude. When this correction was made assuming Non-Inverted Barometer Model the standard deviation of the residual was 1.07 μgal, whereas, when it was made assuming Inverted Barometer Model the standard deviation was somewhat lowered to 0.78 μgal.View full abstractDownload PDF (1654K) -
Tsuneji Rikitake1993 Volume 39 Issue 3 Pages 313-315
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSAnnual rates of maximum shearing strain are estimated for the geodetic triangles covering the Sagami Bay which was the epicentral area of the 1923 Kanto earthquake of magnitude 7.9. The mean rate amounts to 4.7×10-7/year fora period from 1925 to 1991. The increase in the probability of earthquake occurrence is evaluated from the strain rate thus obtained. It is evaluated that the proba bility of an earthquake occurring there within 10 year's period from 1993 amounts to 11 percent.View full abstractDownload PDF (353K) -
Fumiaki Kimata, Yumi Hirose, Yoshimi Sasaki1993 Volume 39 Issue 3 Pages 317-319
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSExcess pass delay (EPD) in the troposphere on Takayama-Nagoya and Takayama-Hachijo baselines was estimated from the surfacemeteorological condition using with the Hopfield model in February, May, August and November 1992. Longterm repeatability of the horizontal vectors on the two baselines is improved by 3 to 6 mm by the correction of EPD. North-South components of the baseline vectors show a seasonal variation of 10 to 32 mm in August 1992. It is clear that the correction of EPD is necessary to discuss GPS measurements with an accuracy of 1×10-7.View full abstractDownload PDF (399K) -
Torao Tanaka1993 Volume 39 Issue 3 Pages 321-322
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSDownload PDF (283K) -
[in Japanese]1993 Volume 39 Issue 3 Pages 323-324
Published: September 25, 1993
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSDownload PDF (243K)
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