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Volume 24 (1978)
- Issue 4 Pages 183-
- Issue 3 Pages 111-
- Issue 2 Pages 59-
- Issue 1 Pages 1-
Volume 24, Issue 4
Displaying 1-8 of 8 articles from this issue
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Hirokazu TAJIMA1978 Volume 24 Issue 4 Pages 183-190
Published: March 25, 1979
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSSimultaneous gravimetric observations of earth tides have been carried out by means of two LaCoste and Romberg gravimeters during the period of about three months from December 1977 to March 1978 at the Aburatsubo Crustal Movement Observatory . Anomalous drift amounting to 30 ?Egal appeared simultaneously in both the gravimeters about one week before the Izu-Oshima Kinkai Earthquake . However, the corre sponding anomalous changes have never been found in oceanic level and crustal inclination data. At the Nokogiriyama Crustal Movement Observatory, gravimetric drift has not appeared at the same time.View full abstractDownload PDF (571K) -
Hideo HANADA, Michio YANAGISAWA, Ichiro MURATA1978 Volume 24 Issue 4 Pages 191-201
Published: March 25, 1979
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSThe absolute gravimeter newly developed in the Earthquake Research Institute, University of Tokyo, uses a small-size cat's-eye as a falling object. As a relative accuracy of 1×10-9 is required for an absolute gravimetry, the angle of rotation of cat's-eye around its center of gravity is limited to about 15 seconds. In order to realize a non-rotating free fall, TSUBOKAWA et al. (1976) proposed a method of making use of a ceramic base as a cat's-eye supporter. The advantage of this method lies in the fact that, in a moment of separating from the supporting beam, the cat's-eye stays instantaneously in the air due to a rapid piezoelectric contraction of a ceramic base. Such a condition may be realized by controlling the delay time of separating the supporting beam from the electromagnet. In this experiment, in order to shorten the delay time, the starting motion of the supporting beam is accelerated by a spring and a reverse excitation current is fed immediately after cutting off the excitation current. It is found as a result, however, that about forty percent of trials has been unsuccessful due to unexpected elastic oscillations of the supporting beam. This percentage later has much improved by making a strong spring for accelerating the beam motion.View full abstractDownload PDF (5168K) -
—Comparison of data observed by extensometers at the OGA and the NIBETU stations—Toshiya SATO, Kenji TACHIBANA, Hiroshi ISHII1978 Volume 24 Issue 4 Pages 202-213
Published: March 25, 1979
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSData observed by the extensometers installed at the OGA and the NIBETU stations of the Akita Geophysical Observotary for the period of 1967 to 1975 are analyzed. The distance between the stations is apart about 39 km and a comparative study for the ground strain is performed. Short and long period strain characteristics are clarified using Chebychev function technique. It is found that the areal strain variations for both the stations are similar and variations of the maximum shear strain at the NIBETU station appears 2.5 years faster than those at the OGA station. An anomalous strain change at the end of 1973, recorded at many crustal movement observatories in Japan, was also observed by both the stations. It is noted that comparisons of the principal strains with data obtained from seismic and geodetic methods show good agreement.View full abstractDownload PDF (1050K) -
Katsumi NAKANE1978 Volume 24 Issue 4 Pages 214-225
Published: March 25, 1979
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSCrustal movements associated with the 1923 Kanto, Japan, earthquake have been studied by some investigators but reliable results using the second order triangulation stations are not yet obtained. The author newly adjusted the preseismic and postseismic second order triangulation network together with the preseismic and postseismic first order triangulation network in the Kanto district and obtained the coseismic horizontal crustal movements. In this report, the results of calculations are presented without any tectonic inter pretation.View full abstractDownload PDF (1314K) -
Hironori TSUKAMOTO, Ichiro NAKAGAWA1978 Volume 24 Issue 4 Pages 226-233
Published: March 25, 1979
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSEffects of oceanic tides on tidal variations of gravity at Kyoto and Mizusawa, Japan were estimated for two principal diurnal constituents O1 and K1. In the estimation, tidal charts which were newly drawn by the present authors were used for seas adjacent to Japan. The value of tidal factor of gravity for 01 constituent free from the oceanic effects is excellently coincident with that computed theoretically for the earth's model, taking the dynamic effects of liquid core into consideration . However, it seems that there still remain some inaccuracies of about 10 percent at present, due to incompleteness of the tidal charts employed in the estimation.View full abstractDownload PDF (781K) -
Paris, 11-16 September 1978Ichiro NAKAGAWA, Tetsuro HAYASHI1978 Volume 24 Issue 4 Pages 234-252
Published: March 25, 1979
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSDownload PDF (2909K) -
Chikara SUGAWA1978 Volume 24 Issue 4 Pages 253-256
Published: March 25, 1979
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSDownload PDF (657K) -
Seismological Mission to the People's Republic of1978 Volume 24 Issue 4 Pages 257-260
Published: March 25, 1979
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSDownload PDF (604K)
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