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Volume 40 (1994)
- Issue 4 Pages 301-
- Issue 3 Pages 215-
- Issue 2 Pages 101-
- Issue 1 Pages 1-
Volume 40, Issue 1
Displaying 1-8 of 8 articles from this issue
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Shuhei Okubo1994 Volume 40 Issue 1 Pages 1-16
Published: March 25, 1994
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSGravity field suffers perturbation when a dislocation source excites deformation, which perturbs the density field. We discuss the gravity and its potential changes for three cases: (1) a point dislocation in a homogeneous half-space, (2) faulting on a finite rectangular plane in a homogeneous half-space, and (3) faulting in a spherically symmetric earth. We will present analytic formulas of the gravity and potential changes for the first two cases, and present a series expression for the third case. They enable us to evaluate coseismic changes in surface gravity and geoid height.View full abstractDownload PDF (1394K) -
Athanasios Dermanis1994 Volume 40 Issue 1 Pages 17-32
Published: March 25, 1994
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSA method is presented for the direct computation of invariant deformation parameters such as dilatation, maximum shear strain and direction of maximum shear from the distances between three points, under the usual assumption of a homogeneous deformation field within the relevant triangular finite element. In addition equations are presented for the evaluation of the accuracy of the deformation parameters (variances and covariances) from the accuracy of the used distances, which may either be observed directly, as e.g, in the case of GPS observations, or computed in the adjustment of a geodetic network. An illustrative example for the case of an equilateral triangle gives an insight into the expected accuracies under different deformation situations. Equations for the determination of deformation parameters and their accuracy are also presented, without the usual infinitesimal approximations, for the coordinate (finite element) method and the method of "multi-side lengths" .View full abstractDownload PDF (1177K) -
Takao Tabei, Shigeo Watanabe, Tomoaki Satake1994 Volume 40 Issue 1 Pages 33-44
Published: March 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSGeoid undulation differences were determined at 13 sites in Shikoku region, Southwest Japan, by combining ellipsoidal height obtained by GPS measurement with normal orthometric height by leveling. Main error factors were evaluated, one of them was the determination error of ellipsoidal height by GPS measurement and another was the vertical crustal movement during the time gap between GPS measurement and leveling. The total error was estimated to be smaller than 10 cm. The results were compared with the ORI-89 geoid model derived from satellite altimeter data and surface gravity data. Two types of geoid undulation differences were generally in agreement with each other. The discrepancy between them was about 32 cm in root mean square. Characteristic features of the geoid undulation obtained are the upheaval in the eastern part of Shikoku and the downward steep slope in the western part. Peak-to-peak amplitude of the geoid undulation difference exceeds four meters in the region extending over a few hundreds kilometers in a horizontal scale.View full abstractDownload PDF (1406K) -
Tsutomu Saito1994 Volume 40 Issue 1 Pages 45-62
Published: March 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe newly developed method for adjusting a traverse network through transforming the observation of the traverses into equivalent fictitious observations of a network of sides and directions between the junctions of the net, is described. In addition to this, related formulas to Schreiber's rule used in this adjustment are derived by means of the theory of the generalized inverses together with a numerical example .View full abstractDownload PDF (1507K) -
Shigeaki Otsuka1994 Volume 40 Issue 1 Pages 63-79
Published: March 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSContinuous observations of crustal deformation have been carried out at Rokko-Tsurukabuto observation station since 1970, in order to study the behavior of crustal deformation in and around the fracture zone of an active fault. The station is located at Tsurukabuto incline of the Rokko tunnel of San'yo Shinkansen in Kobe City, southwestern Japan. An observation tunnel of the station was excavated across Otsuki fault that is typical of active faults with a strike of NE-SW in the Rokko mountain area . The following results were deduced from the observations with extensometers during the period of 1977-1984. The secular strain rates observed were about one order of magnitude greater than those observed at other stations. The largest one was nearly 1 ×10 -5/ year . The direction of the maximum compressive axis of average strain rates outside the fracture zone, on the north of the main fault-gouge layer of the Otsuki fault, was WNW-ESE. This direction was almost coincident with that of horizontal stress obtained through in situstress measurements at the Rokko-Suwayama site. On the other hand, the direction of the maximum compressive axis in the fracture zone, on the south of the main faultgouge layer of the Otsuki fault, was nearly perpendicular to that outside the fracture zone. The absolute values of average strain rates inside and outside the fracture zone decreased 30-70% after the end of 1980. Seismic activity in the region around Osaka Bay became active almost simultaneously. It seems that the strain rate changes observed at the Rokko-Tsurukabuto station reflect the tectonic activity of the crustal block that is bounded by active fault systems such as Arima-Takatsuki Tectonic Line, Median Tectonic Line, active faults in the region from the Ikoma to the Kongo mountains and an active fault system from the Rokko mountains to Awaji Island.View full abstractDownload PDF (2492K) -
Hiroshi Sato1994 Volume 40 Issue 1 Pages 81-85
Published: March 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSActive fold, discovered first by Otuka in the beginning of 1940's along the Yoneshiro River by the analysis of leveling data, has a important significance that the tectonic stress yielded such folding is still active today. After his discovery, several findings of such active fold were reported in the Fossa-Magna fold zone. It was, however, pointed out by some reseachers that no sure evidence of active fold had been yet found. The author analysed the recent leveling data along the Yoneshiro River, and obtained the crustal movement that supports Otuka's discovery of active fold.View full abstractDownload PDF (421K) -
Sun Tian-xi1994 Volume 40 Issue 1 Pages 87-88
Published: March 25, 1994
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSThe author proposed a model of plate breakup in the Japan Sea in 1983 (Sun, 1983), and predicted that shallow earthquake of M.7 or over will occur before 1993 off the west coast of Central Japan, from the model of plate breakup and migration of epicenters in the shallow earthquakes in the Japan Sea, at the international symposium in 1987 at Beijing, China (Sun, 1987). The occrrence of the Off Noto Peninsula Earthquake on 7th, Feb. 1993 demonstrated that the medium-term prediction made by the author in 1987 came true. The success of this prediction should provide an impetus to the researches on earthquake prediction elsewhere.View full abstractDownload PDF (295K) -
Jiro Segawa, Yoshiaki Tamura, Kazuo Shibuya, Seiichi Shimada, Kosuke H ...1994 Volume 40 Issue 1 Pages 89-96
Published: March 25, 1994
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSDownload PDF (889K)
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