All issues
Volume 28 (1982)
- Issue 4 Pages 193-
- Issue 3 Pages 121-
- Issue 2 Pages 73-
- Issue 1 Pages 1-
Volume 28, Issue 3
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
-
Tsuneya TSUBOKAWA, Sinzi NAKAI1982 Volume 28 Issue 3 Pages 121-133
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe high resolution and good linearity of the readout system of the LaCoste & Romberg gravimeter justify both a better method for setting the beam position and a better measuring procedure than those described in the manufacturer's instruction manual. The effects of hysteresis following unclamping are reduced if the tilt angle in the direction of the long level is increased, so long as the beam remains horizontal. Moreover, the remaining effects are eliminated by our reading procedure. In this procedure, the output voltage corresponding to the beam position, with a dial setting which does not correspond to the null position, is recorded one minute after unclamping. The dial setting is then changed to bring the beam to the other side of null and the beam position voltage is again recorded one minute later. Finally, the dial is returned to its first position and, after one minute, the beam position is again recorded. The null dial setting can then be determined by interpolation. A new data processing system has been developed to implement the above procedure; this system can also be used for tidal observations. The analog signal from the beam position readout is digitized with an adjustable sampling interval. 101 consecutive digitized values are filtered using a digital low pass filter with trigonometric weights designed by Akaike; this filter has no phase lagg which is an advantage for recording the tides. Its purpose in both field and tidal measurements is to eliminate the effect of microseisms. The following features make the system suitable for field use :1) it is battery operated and has a digital printer.2) all the necessary computations are performed by a built-in microprocesser.3) the print-out includes the environmental factors of temperature, air pressure and level of background vibrational noise. For tidal observations, the system has a D/A converter so that the filtered output can be monitored with a chart recorder. Tests have shown the system to work well both for field gravity measurements and for tidal observations.View full abstractDownload PDF (4639K) -
Shigeaki OTSUKA, Yoshiaki TAMURA, Kunio FUHMORI, Yutaka TANAKA1982 Volume 28 Issue 3 Pages 134-151
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSIn order to investigate crustal movements of an active fault and its vicinity, continuous observations by many extensometers and tiltmeters have been going on at the Ootsuki Fault since 1970 except the interrupted period from 1972 to 1975. The Rokko-Tsurukabuto observation station is located at the Tsurukabuto Incline leading into the Rokko Tunnel of the Sanyo-Shinkansen of Japanese National Railways. Results of observation by six extensometers for the period from July 1977 to February 1980 are described in the present paper. It seems that observed curves are caused by secular change with linear trend, annual variation and the changes corresponding to the rainy season. Average strain rates during about 2.5 years show the large values of 1-10μ strain/year. The direction of principal axis of the secular strain rate at the north side of the fault is in WNWESE. It almost coincides with the direction of the regional tectonic stress inferred from some other researches. On the other hand, that at the south side is perpendicular to one at the north side. The features of annual variation and effects of the rainy season have much in common. Both the phenomena could be caused by the pressure changes of the ground water due to the precipitation. It is found that there are considerable differences between the north and south sides of the fault in all these phenomena. These analyzed results may suggest the characteristics of the crustal deformation in the vicinity of the fault.View full abstractDownload PDF (2916K) -
-Result of Calculated Earth Strains-Katsumi NAKANE, Yoichiro FUJII1982 Volume 28 Issue 3 Pages 152-161
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe characteristics of earth strain in the KANTO-TOKAI district calculated from the displacement vector are summarized as follows:1) The elongation with almost NNW-SSE direction is quite remarkable during for the coseismic earth strain of the 1923 KANTO earthquake.2) The principal axis of the postseismic compression is quite reverse as compared with the coseimic one.3) The principal axes of compression during the interseismic period are directed toward NW-SE in the TOKAI district, NNW-SSE in the KANTO district, and N-S in the BOSO peninsula.4) The maximum shear strain rates during the interseismic period are 2×10-7/yr. in the TOKAI district and 4×10-7/yr. in the KANTO district. In the KANTO district the calculated strain rate will be affected by the after effect of the 1923 KANTO earthquake.View full abstractDownload PDF (825K) -
-Geoid around Antarctica-Jiro SEGAWA, Tatsushi ASAOKA1982 Volume 28 Issue 3 Pages 162-171
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSMeasurements of sea surface height provided by SEASAT-1 altimetry are thought to be as accurate as ±10 cm from the engineering viewpoint only. However, actual altimeter data involve errors to the amount of ±5 m because of errors in satellite orbit prediction. In this paper, by considering the height differences at numerous orbital crossings as randomly distributed, the predicted height of SEASAT has been corrected using the standard deviation of the height differences. After this correction the marine geoid in the area from 45°S to the margin of Antarctica has been evaluated on the basis of the improved sea surface height. The geoid thus obtained has a relative accuracy to the order of ±60 cm.View full abstractDownload PDF (1146K) -
Yoshihiro NISHIMURA, Ichiro NAKAGAWA, Toshihiro HIGASHI, Junichiro MIY ...1982 Volume 28 Issue 3 Pages 172-173
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSGravity survey was carried out as densely and precisely as possible around Togo-ike, northwest Japan, in 1981.It was found that the area swarming with hot spring resources corresponds to the locally thick alluvium at Togo Spa.View full abstractDownload PDF (308K) -
Kazuaki NAKAMURA1982 Volume 28 Issue 3 Pages 174-176
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESS -
Yukio HAGIWARA1982 Volume 28 Issue 3 Pages 177-178
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe vertical gradient of normal gravity usually taken as -0.3086 mgal/m everywhere on the earth's surface. This value is obtained on the assumption that the shape of the earth is sphere and its entire mass is concentrated on its gravity center. The rigorous expression of the vertical gradient of normal gravity can be obtained from the normal gravity potential. In this case, the mathematical formulation is made in the spheroidal coordinate system on the basis of the fact that the shape of the earth is approximately an ellipsoid of revolution. The obtained results indicate that the vertical gradient of normal gravity ranges from -0.3083 mgal/m (high latitudes) to -0.3088 mgal/m (low latitudes).View full abstractDownload PDF (202K) -
Tadao WAKASUGI, Tatsutoshi TAKAHASHI1982 Volume 28 Issue 3 Pages 179-180
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe purpose of the observations is to clarify secular variation of ground tilt at the Ogi Peninsula, Sado Island. It is noticed for uplifting and northward tilting of the Ogi Peninsula at the time of the 1802 earthquake. Automatic level measurements indicate that the variation of ground tilt has been very small during the period from 1972 to 1982.View full abstractDownload PDF (205K) -
Shuhei OKUBO1982 Volume 28 Issue 3 Pages 181-182
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSPartial derivatives of Love numbers include Dirac's delta functions, which become infinite at the solid/liquid interfaces. 100% change in liquid density at the mantle-core boundary induces significant variations in Love numbers; 40% change in h2", 20% change in h2', 10% change in l2' and 7% change in k2'. Precise measurements of Love numbers pose a strong constraint on liquid density at the top of core. Taking 1% uncertainty in the liquid core density into account, we expect 0.1-1% uncertainty in Farrel's Green function.View full abstractDownload PDF (179K) -
[in Japanese]1982 Volume 28 Issue 3 Pages 183-184
Published: 1982
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSDownload PDF (265K)
- |<
- <
- 1
- >
- >|