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Volume 30 (1984)
- Issue 4 Pages 249-
- Issue 3 Pages 169-
- Issue 2 Pages 75-
- Issue 1 Pages 1-
Volume 30, Issue 4
Displaying 1-9 of 9 articles from this issue
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Naosuke SEKIGUCHI1984 Volume 30 Issue 4 Pages 249-253
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe decade fluctuation of the acceleration of the Earth's rotation is repeated almost periodically with period about 25 years. Its semi-amplitude is about 0.1 s⋅yr-2. The power spectrum of its variation has low values for the frequencies between (3 yr)-1=0.33 yr-1 and (12.5 yr)-1=0.08 yr-1. Therefore, we can imagine that the causes of the fluctuation are divided into two parts by this frequency interval.View full abstractDownload PDF (431K) -
Tsutomu SAITO, Yoichiro FUJII1984 Volume 30 Issue 4 Pages 254-263
Published: February 25, 1985
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSOn condition that row sums in the design matrix are exactly zero, formulas for the least squares adjustment of free levelling networks are established. The relationships between the adjustment of free and a-point-fixed networks are also discussed.View full abstractDownload PDF (816K) -
Masakuni HASHIDA, Kunihiro SHIGETOMI1984 Volume 30 Issue 4 Pages 264-273
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe length change of a rod of an extensometer, which is caused by a temperature change and force acting on an extensometer, produces an error in the measurement by an extensometer. The length change of a rod depends on its coefficient of linear expansion, its coefficient of elasticity and so on. Observations by the super-invar extensometer and the fused quartz extensometer installed on the common base have been carried out at Osakayama Crustal Deformation Observatory. The measurement by the super-invar extensometer (E4B) and one by the fused quartz extensometer (E5B) are in good agreement except the case of remarkable temperature changes. It is concluded that measurements by extensometers used in the present study are the sum of the ground strain and the length change of rods of extensometers, i.e. super-invar and fused quartz, caused by a temperature change. Coefficients of linear expansion of super-invar and fused quartz on the observational condition have been estimated by making use of the phenomenon that an adiabatic temperature change caused by a pressure change whose period is a few hours produces only the length change of the extensometer. The coefficient of linear expansion of super-invar is negative and its absolute value is about 1 × 10-7/°C. That of fused quartz is positive and its value is about 1 × 10-7/°C. These values are effective in case that periods of temperature changes are less than 1 day. In an analysis of Earth tidal strains, the combination of the measurement by the super-invar extensometer and one by the fused quartz extensomemeter, i.e. (E4B+E5B)/2 is free from temperature changes and indicates the ground strain. As a result of analyzing (E4B+E5B)/2, amplitude ratios to Body tidal strains (1=0.0832, h=0.6114) are constant of 0.5-0.6 for M2, S2, and O1: and the amplitude ratio for K1 varies during the period from October 1983 to March 1984.View full abstractDownload PDF (1076K) -
-Laboratory and Field Experiments-Michio YANAGISAWA1984 Volume 30 Issue 4 Pages 274-286
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSOur purpose is to measure crustal strain of the order of 10-9 using resistive strain gauge in the tunnel of the Nokogiriyama crustal movement observatory. In the experiments, we connect waterproof type strain gauges to an electronic bridge circuit. For glueing the strain gauges on the rock wall, epoxy resin was used together with moisture proof butyl rubber. Strain gauge observations of earth tide have been successed. By comparing extensometer results with the strain gauge ones, we see that both of them show a good coincidence each other.View full abstractDownload PDF (8322K) -
-Application do Kyuroku-shima Island-Ken'ichiro YAMASHINA, Takaaki FUKUDOME1984 Volume 30 Issue 4 Pages 287-296
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSA photographic method for surveying the vertical crustal deformation at coast is discussed. The elevation of a target can be obtained after estimating (1) the distance of the camera from the target (or the focal length of the camera), (2) the height of the camera (namely, height of the horizon) above the sea level at shooting time, and (3) the correction of the tidal height. For the present purpose, the pictures as follows are favorable. (1) The horizon lies across the picture. (2) The optic axis of the camera is horizontal. (3) There exist some scales of the distance on the picture. (4) A target is not too high in altitude. (5) There are some pictures taken successively in time, or else, (6) the camera should be kept from the target by several tens of meters.View full abstractDownload PDF (2517K) -
Teruyuki KATO, Satoru HONDA1984 Volume 30 Issue 4 Pages 297-306
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSVLBI technique serves us with a very useful tool in finding relative plate motions. The accuracy of distance determination by the technique is now reaching to a few to several centimeters. Therefore, even a few years of repeated VLBI observations may detect plate motions, if station locations are adequate. The present paper examines the capabilities of VLBI technique in monitoring plate motions in case that one of two stations is located in Japan. Numerical simulations are conducted for this purpose based on simple assumptions on the plate motions as follows; 1) Plates move as rigid materials. 2) Relative motions of plates are subject to Minster and Jordan (1978) and Seno (1977). 3) Two different cases are considered as for the plate boundary close to Japan. Three representative locations are considered as for a VLBI station in Japan: they are 1) Hokkaido, 2) Central Honshu, and 3) Kyushu. Simulations are carried out under the condition that the relative plate motion should be recognized by a twice of successive VLBI observations, within ten years and for distances between two stations less than 8000 km. After some numerical simulations, we found several possibilities on the detectabilities of relative plate motions surrounding Japan as follows: 1) If we put stations in Japan, relative plate motions between Eurasian, Pacific, Philippine Sea, North American, Indian and Arabic plates are detectable, while those between a Japanese station and stations on African, Antarctic, Cocos, Nazca and Caribbean plates are not detectable. 2) Motion of Pacific plate can be detected within one year, if we put an accompanied station at Hawaii. 3) Fiducial station in Kyushu would have some advantages in watching Philippine Sea and Arabic plates, 4) Kashima is not a suitable location to watch Philippine Sea plate. 5) It takes three to four years to find relative motion between Eurasian and North American plates, if we put stations in Hokkaido and Kyushu. 6) Indian plate motion could be detected in a few years, if station locations are suitable. These suggestions could be usefully considered when we plan the VLBI station net-work in Japan, although we should be careful in direct applications of these results because of oversimplifications in assumptions.View full abstractDownload PDF (1142K) -
Eiki ONODERA1984 Volume 30 Issue 4 Pages 307-312
Published: February 25, 1985
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSWe investigate the Southern Oscillation, one of large-scale atmospheric phenomena, in relation to variations of the rate of the Earth's rotation. The results show that the variation of the former appears by 2-3 years in advance of the variation the latter. This fact suggests that there is some correlation between the two variations .View full abstractDownload PDF (451K) -
Toshio FURUTA, Hiromi FUJIMOTO, Yoshibumi TOMODA, Kazuo KOBAYASHI, Hid ...1984 Volume 30 Issue 4 Pages 313-322
Published: February 25, 1985
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSA handy acoustic transponder navigation system using the long-baseline method has been newly developed and operated by the research vessel Tansei-Maru and Hakuho-Maru on their cruise KT 83-19, KT 84-2 and KH 84-2, The results of position fixing were sufficiently accurate for usual scientific purposes. The system will be useful for detailed topographic and geophysical mapping as well as dredge hauls, coring and installation of ocean-bottom instruments, after some minor problems in the specification are improved.View full abstractDownload PDF (1014K) -
Ichiro NAKAGAWA, Toshihiro HIGASHI1984 Volume 30 Issue 4 Pages 323-324
Published: February 25, 1985
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSPrecise gravity measurements were carried out by means of three and two LaCoste & Romberg gravimeters on December 1973 and December 1983, respectively, in the southeastern part of Shikoku District, in order to detect the secular change of gravity. The results obtained show that the gravity value has been increased a few tens of microgals during the period concerned, but its amount was less than that prospected from the results of levelling surveys which were performed during the almost corresponding period.View full abstractDownload PDF (254K)
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