巻号一覧
18 巻 (1972)
- 4 号 p. 161-
- 3 号 p. 99-
- 2 号 p. 49-
- 1 号 p. 1-
18 巻, 2 号
選択された号の論文の7件中1～7を表示しています
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田中 寅夫1972 年 18 巻 2 号 p. 49-57
発行日: 1972/09/30
公開日: 2011/07/05
ジャーナル フリーEarth tilts and strains due to oceanic tides at two stations, Akibasan and Oura, in Wakayama, Japan have been estimated. The effects produced by the neighbouring sea have been calculated according to the theory of deformation of a multi-layered halfspace by J. T. Kuo. For the effects of the distant sea, Green's function method by I, M. Longman for the Gutenberg earth model has been used. Tilts and strains observed at Akibasan can be explained successfully by summing the direct earth tides expected from the Gutenberg model and the indirect effects due to oceanic tides expected from a similar model (The Gutenberg crust is replaced by a structure determined by local seismological observations). The surface tilt on this multi-layered model can be roughly expressed by the Boussinesq solution multiplied by the factor 12.6/(3.0+r) introduced by E. Nishimura. Decreasing rates of the tilt and strain to distance r are approximately proportional to r-2.4, which is equal to the decrease of strain steps with distance from moderate earthquake sources found by S. Takemoto et al. It is also nearly equal to the decreasing rate of an anomalous ground strain observed before and after the Yoshino Earthquake in 1951 by M. Takada.抄録全体を表示PDF形式でダウンロード (1026K) -
藤井 陽一郎1972 年 18 巻 2 号 p. 58-61
発行日: 1972/09/30
公開日: 2010/09/07
ジャーナル フリーThe author attempts to explain the high gravity anomalies which are found near the points of seismic upheavals along the boundary of Philippine Sea Plate in Southwestern Japan in terms of plate tectonics. The continental lithosphere is collided, contracted and pulled down by the oceanic lithosphere and after elastic rebound which is nothing but the occurence of an earthquake, some amount of strain may be remained. This means increase of density. Thus, after so many recurrence of earthquakes, high gravity anomalies are formed, and this can be estimated asΔg=2πkΔph, where k is universal constant of gravitation, Δp change of density of slab and h thickness of slab (Fig. 3). Yearly rate of Δp, Δp/Δt, is estimated as 3.25X0.6X10-7/year based on the horizontal deformation of the crust found by geodetic works. Putting h=100 km, yearly change of gravity isΔg/Δt =0.817 μgal/year. It has elapsed about 12.5x104 years after the beginning of convergence of oceanic lithosphere. Therefore, present anomalies areΔg =102.1 mgal. The average of Bouguer anomalies near the five points of seismic upheavals is 90 mgal (see Fig. 1 and Table 1). This coincidence shows that the mechanism of formation of high gravity anomalies can be explained in terms of convergent plate. Finally, the author points out that the detection of gravity change associated by the convergence of plate can be possible by means of modern gravity meter with special observation techniques or available apparatus for absolute measurement of high precision.抄録全体を表示PDF形式でダウンロード (370K) -
萩原 幸男1972 年 18 巻 2 号 p. 62-71
発行日: 1972/09/30
公開日: 2010/09/07
ジャーナル フリーThe truncation errors for the geoidal height and the deflection of the vertical were first investigated by Cook [2]. Molodenskii et al. [3] later derived the truncation error formulas by using the truncation coefficient Qn. In the present paper, the author gives the general formula of Qn and the mathematical relationship between Qn and Cook's truncation function qn. de Witte [1] pointed out that the truncation error formula for the deflection of the vertical introduced by Hirvonen & Moritz [4] was invalid in contrast with Cook's treatment. It is proved in the present paper that Molodenskii's truncation formula is equivalent to Cook's. The truncated gravity anomaly is based on a mass distribution different from the "real" mass distribution which causes the global geoidal -height, so that the truncation yields the apparent mass-transport. The center of the "real" geoid does not coincide with one of a geoid calculated from the truncated gravity anomaly. The local geoid which best fits the truncated gravity anomaly is discussed in relation to the masscenter dislocation.抄録全体を表示PDF形式でダウンロード (911K) -
志知 龍一1972 年 18 巻 2 号 p. 72-77
発行日: 1972/09/30
公開日: 2010/09/07
ジャーナル フリーIn order to find a forerunner of earthquake in the continuous recording of crustal movement, the elimination of various noises such as due to the earth tides and meteorological changes must be taken into consideration. Digital band pass or high cut filters in common use, however, have their own merits and restrictions. There are yet rooms for the improvement in digital filter technique for this purpose. An effective method which minimized the waste of data at the both ends. of the record was devised for the repeated operation of suitable filters, in order to achieve a sharp cutoff of fluctuations with periods shorter than that of diurnal components of the earth tides . The method was successfully applied to the extensometric records obtained at the Inuyama Crustal Movement Observatory for the period containing two remarkable earthquakes, one occurred in the central part of Gifu prefecture on Sept . 9, 1969 (M=6.6, Δ=50 km) and the other, off the Atsmi Peninsula on Jan. 5, 1971 (M=6.3, Δ=90 km). However, no significant signal which could predict the earthquake was found in the period from 1 day to 1 month before the earthquake, and the ground deformations were considered to be mainly associated with the changes due to atmospheric pressure and discharged water from the observational vault.抄録全体を表示PDF形式でダウンロード (541K) -
鍋谷 祐夫, 鈴木 正芳, 野沢 保, 田結庄 良昭1972 年 18 巻 2 号 p. 78-88
発行日: 1972/09/30
公開日: 2010/09/07
ジャーナル フリーBouguer gravity anomalies were studied on Ibaragi district near Osaka, Japan, with regards to emplacement structure of granitic complex intruded into the paleozoic sediments. The gravity anomalies observed seemed to finely correspond to the distribution of granitic rocks over the area. Rock facies of the complex are changed from adamellite at the central zone to quartz diorite in the marginal shell, but the most parts of it are coarse-grained granodiorite whose density is considerably smaller than the quartz diorite or paleozoic rocks, and obviously give a negative anomalous zone of gravity in the surveyed area. Gravity anomaly was analytically explained with two or three dimensional models of subsurface structures in which the complex had a light central mass under the southwestern area and extended toward northwest at the deeper horizons. Continuated gravity fields suggest that the Myoken pluton is not isolated in place, but get emplacement near the northern part of the Nose.抄録全体を表示PDF形式でダウンロード (1093K) -
住友 則彦1972 年 18 巻 2 号 p. 89-91
発行日: 1972/09/30
公開日: 2011/07/05
ジャーナル フリーPDF形式でダウンロード (1228K) -
地球回転に関する国際シンポジウム(盛岡1971)弓 滋1972 年 18 巻 2 号 p. 92-96
発行日: 1972/09/30
公開日: 2010/09/07
ジャーナル フリーPDF形式でダウンロード (571K)
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