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Volume 20 (1974)
- Issue 4 Pages 153-
- Issue 3 Pages 107-
- Issue 1-2 Pages 1-
Volume 20, Issue 4
Displaying 1-14 of 14 articles from this issue
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Hirokazu TAJIMA, Sadakatu IZUTUYA1974 Volume 20 Issue 4 Pages 153-168
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSGravity change measurements may be one of the easier ways of detecting tectonic changes induced by an earthquake. In this paper, the gravity data measured during and after the Matsushiro Earthquake Swarm are compiled, and the relationship between gravity and elevation changes is discussed. It is concluded that the elevation of the epicentral area lifts up without any change in subsurface apparent density but sinks with a density increase. We have recently observed density decrease there again, but a possible cause of the decrease remains still unknown.View full abstractDownload PDF (1440K) -
Michio YANAGISAWA1974 Volume 20 Issue 4 Pages 169-177
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSIn the TEM tiltmeter [1] [2] [3], variation of tilt is mechanically amplified with a cross suspended pendulum whose deflection is transformed to electric signal through a differential transformer. In this instrument, a small effect due to variation of the geomagnetic field still; remained in spite of magnetic shield of the transformer. This was eliminated by using a case of steel of high permeability. Small inclination of the mounting table is given by a micrometer screw incorporated with a lever and two parallel plate spring system as a reduction mechanism. In the oldtype instrument, the turn values of the micrometer head were calculated from the dimensions of the reduction mechanism. It is found, however, that these calculated values are somewhat different from the experimental values measured with a precise dial-gauge (several per cent). It is ascertained that the drift rate may become smaller than 1×10-6(0"2) per year. The author also analysed the both data obtained with VM and TEM tiltmeters installed in the Akagane Station (Mizusawa) by the method of least squares.View full abstractDownload PDF (3108K) -
Izuo OZAWA1974 Volume 20 Issue 4 Pages 178-187
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSComponents of earth tides can be classified into three types. The first type is expressed by a product of a constant term F1(h, k, l) which consists of the tidal numbers h, k, 1 and does not contain functions of latitude and the potential W2 of the tide generating force. The second type is expressed by a product of a constant term F2(h, 1) which consists of the tidal numbers h, l and does not contains a function of latitude, and the potential W2 of the tide generating force. The third type is expressed by a product of a constant term F3(h, l, θ) which consists of a combination of products of the tidal numbers h, 1, and a function of co-latitude, θ, and the potential W2 of the tide generating force. Patterns of the latitudinal and the azimuthal distributions of these types' components are calculated. Then, a possibility to obtain the ratio h/l is shown from the patterns of the latitudinal and the azimuthal distributions of the tidal extension which belongs to the third type.View full abstractDownload PDF (887K) -
Sadakatu IZUTUYA, Hirokazu TAJIMA, Yukio HAGIWARA, Ichiro MURATA1974 Volume 20 Issue 4 Pages 188-192
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSA locally destructive earthquake occurred on the coast of Izu peninsula (λ=138°48', p=34°34', M=6.9) on May 9th, 1974. The route of bench marks around the epicentral area had been established and surveyed at the level of the third order (closing error 47 mm) by Minami-Izu Town Office in June, 1973. In order to evaluate the coseismic land-deformation, the writers have carried out the resurvey of the first order levelling along the route of bench marks from Shimogamo (B.M. No. 9364) to Iruma Village, in September, 1974. The total length of the route amounts to about 28 km. Comparing the levelling with relevelling results, the relative vertical displacement of bench marks during 14 months are listed in Table I, where B.M. No. 9634 is assumed to be fixed. According to the analysis by means of the "sine-method", we find the coseismic land-tilting having the maximum inclination of 2" to 3" in the direction parallel to the Irozaki Fault which moved actively with a right rateral slip. The vertical displacement previously expected from the fault motion has not been explicitly detected.View full abstractDownload PDF (519K) -
Minoru TANAKA, Taketsune HOSONO, Tadao KUBOKI, Shinichi OWADA, Toru TA ...1974 Volume 20 Issue 4 Pages 193-208
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSGeomagnetic and gravity surveys in the Bonin island (Chichijima), located in the central part of Izu-Bonin island arc were carried out by the Geographical Survey Institute in December 1973 and March 1974, respectively. The recent first geomagnetic and gravity surveys in this island have been done by the members of the Kakioka Magnetic Observatory since January 1971 and the Geographical Survey Institute from January to February in 1971. From these two surveys, the following results are obtained, (1) Geomagnetic secular change of declination at the first order geomagnetic point of Mt. Shigureyama (No. 98) shows the consistent tendency of west increasing in parallel with the extension line of the secular change of declination obtained by the repetition surveys of Hydrographic Department followed after Tanakadate's results at Ogiura. (2) Free air anomaly shows the value of +360 mgal near the central part of the island. Bouguer anomaly shows the value of +340 mgal in the central and the northern parts of the island. This value may be the most maximum one in the island arcs. (3) Geomagnetic anomalies both total (F) and vertical (Z) intensities show the patterns of the distribution due to a underground dipole though these patterns show the inverse correlation in comparison with the intensities of geomagnetic and Bouguer anomalies. These results are compared with the survey results of Oshima (7) island and discussed about the island arc.View full abstractDownload PDF (2584K) -
Ietsune TSUBOKAWA, Michio YANAGISAWA, Chikara SUGAWA, Kennosuke HOSOYA ...1974 Volume 20 Issue 4 Pages 209-220
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe results of a comparison between electromangnetic tiltmeters (TEM) and quartz pendulums (VM) at the Laboratory of Geodynamics of Walferdange have been analysed by a global method. The mean result of all instruments fits very well with those obtained in Western Europe, but the EW component of TEM 16 gives a significantly lower value for M2 than those given by VM pendulums. This may be due to a cavity effect. Diurnal waves for the EW component are in very good agreement between themselves as well as with the Molodensky model 2 introducing the dynamic effects of the Earth's liquid core. The results at Walferdange have a particular importance because instruments working upon basically different principles give the same resonance effects .View full abstractDownload PDF (1131K) -
Tadao WAKASUGI, Keichi KASAHARA1974 Volume 20 Issue 4 Pages 221-224
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
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Syujiro NISHI, Minoru TANAKA1974 Volume 20 Issue 4 Pages 225-226
Published: March 25, 1975
Released on J-STAGE: July 05, 2011
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Noriaki SUDA1974 Volume 20 Issue 4 Pages 227-230
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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Naomi FUJITA1974 Volume 20 Issue 4 Pages 231-232
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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Yoshihide KOZAI1974 Volume 20 Issue 4 Pages 233-235
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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Chikara SUGAWA1974 Volume 20 Issue 4 Pages 236-237
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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Presented to the 7th Meeting of the International Gravity Commission1974 Volume 20 Issue 4 Pages 238-241
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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1974 Volume 20 Issue 4 Pages 242
Published: March 25, 1975
Released on J-STAGE: March 01, 2011
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