巻号一覧
27 巻 (1981)
- 4 号 p. 225-
- 3 号 p. 155-
- 2 号 p. 75-
- 1 号 p. 1-
27 巻, 1 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1981 年 27 巻 1 号 p. 1-10
発行日: 1981/06/30
公開日: 2010/09/07
ジャーナル フリーSecular ground tilts observed at Kishu Mine in Kui Peninsula, Japan from 1952 to 1979 can be represented as exponential functions with a relaxation time of 5.1 years. Assuming the stress-relaxation in a Maxwell body of μ=3×1011, we get the viscosity η=5× 1019 poise. Stress-relaxation in the rock around the tiltmeters is considered the origin of the secular tilts, though stress-relaxation in the metal consisting of the tiltmeters and/or in the concrete base on which the tiltmeters are installed cannot be excluded. No forerunning changes can be found on the secular tilts in periodic ranges longer than 10 days associated with two remarkable earthquakes occurred in Kui Peninsula on Nov. 25, 1973 (Δ=50 km, H=60 km, M=5.9, 5.8). A preliminary analysis of earth tides shows that both the M2 and O1 tilt tides observed at Kishu are well explained as the sum of the solid tides and the oceanic loading effect.抄録全体を表示PDF形式でダウンロード (1578K) -
橋田 匡邦, 重富 國宏1981 年 27 巻 1 号 p. 11-22
発行日: 1981/06/30
公開日: 2011/07/05
ジャーナル フリーTopographic effects on the earth tidal strains have been estimated quantitatively at the extensometer site. The observed M2 and O1 values obtained from four extensometers, installed at Osakayama Crustal Deformation Observatory near Kyoto, have been compared with the predicted ones. Topographic effects have been calculated by means of three dimensional finite element method based on two models. In Model I, the uniform boundary stresses have been applied to the region used in calculation of topographic effects. The amplitude ratios of the observed values to the predicted ones-Body tide corrected by ocean load effects and topographic effects calculated by Model I-are 0.5-0.7 for M2 and 0.5-0.8 for O1. The observed phase lags are almost in good agreement with the predicted ones. It is presumed that one of the possibilities to explain the small observed amplitudes is the crustal block structual effects proposed by Latynina (1973). In Model II, the lower boundary stresses as same as Model I and the upper ones decreasing to zero at the surface have been applied to the same region as Model I. The observed values are in good agreement with the predicted ones-Body tide corrected by ocean load effects and topographic and crustal structual effects calculated by Model II. In Model II, the problems of the depth that the boundary stresses become uniform and the block dimension still remain, but it is infered that the crustal block structure affects the earth tidal strains.抄録全体を表示PDF形式でダウンロード (1102K) -
野崎 京三1981 年 27 巻 1 号 p. 23-32
発行日: 1981/06/30
公開日: 2010/09/07
ジャーナル フリーA program for computation of spherical terrain correction was written, which was particularly intended to manage a large number of gravitational data in an extensive area of high relief. The computational precision stands on less than 1 mgal for round off error. Terrain data used are those of 250×250 m2 grid provided by the Geographical Survey Institute. By using this program and the terrain data, the area of correction can be spherically extended up to a few hundred kilometers or more from each gravity station. The value of terrain correction can, then, be computed more precisely than ever and the relative error associated with terrain and Bouguer corrections could be estimated quantitatively even in an extensive area of high relief. As an application, about 4, 000 gravitational data were adopted which had been available in and around the Central Ranges (Japan Alps), Honshu, Japan. When the terrain correction is made in a distance range 80 kms from each station, the relative error among all stations can be estimated as less than about 1.5 mgals, and the correspoding CPU time by FACOM M-200 computer is approximately 5 sec/station.抄録全体を表示PDF形式でダウンロード (813K) -
―変位ベクトルの誤差―中根 勝見, 藤井 陽一郎1981 年 27 巻 1 号 p. 33-39
発行日: 1981/06/30
公開日: 2011/03/01
ジャーナル フリーAfter net-adjustments of old and new triangulation networks in which the same fixed stations are assumed, we can obtain displacement vector (V) of an arbitrary station by subtracting the old coordinates (X″) from the new coordinates (X′) and the variances and covariances (Σx″, Σx′) of the station are
After rotating the coordinate system with the angle 6, we obtain the following vari-ances
σ2θ″=TΣx″Tt, σ2θ′TΣx′Tt
where T is [cos θ sin θ] and Tt is transpose of T.
Because the new and old observations are uncorrelate, variance of V(σ2v) in the direction θ is given by (σ2θ″+σ2θ′). Substituting the proper values of θ gives the maximum or minimum values of σ2v, which may be reduced to
maximum=1/2(σ2x+σ2y+ω)
minimium=1/2(σ2x+σ2y-ω)
ω-{(σ2x-σ2y)2+4σ2xy}1/2,
where
Direction of principal axis ψ is given by
φ=1/2 tan-12σxy/(σ2X-σ2Y)
By using this method, we estimate the errors of the displacement vectors in KANTO-TOKAI district. As a result of the estimation we fined that the obtained dis-placement vectors are reliable. But we do not consider error of the displacement vector due to error of the fixed stations in this paper.抄録全体を表示PDF形式でダウンロード (435K) -
山内 常生1981 年 27 巻 1 号 p. 40-49
発行日: 1981/06/30
公開日: 2010/09/07
ジャーナル フリーA tank model with three tanks is proposed to simulate strain responses to rainfall, at Mikawa Crustal Movement Observatory, Toyohashi City, Central Japan . The data analyzed are the ground strains observed for the period of three years from 1974 to 1976, and the variation of 222Rn concentration in the same observatory from June to November, 1977. We can calculate accurately strain responses by the proposed tank model from precipitation at the observatory. The error of this tank model roughly amounts to 10% of observed ground strains, and residuals are less than ±1.5 × 10-8. It is found that observed ground strains caused by rainfalls show remarkable disagreements with the calculated values before and after the occurrence of earthquake of Aichi-Gifu Border (M=5.3, Δ=85 Km, H=50 Km) March 14, 1975.抄録全体を表示PDF形式でダウンロード (817K) -
高嶋 重雄1981 年 27 巻 1 号 p. 50-60
発行日: 1981/06/30
公開日: 2010/09/07
ジャーナル フリーIt is already confirmed with calculation that the ideal angle observations are reduced strictly to the equivalent direction observations by the station-adjustment. [1] Author proved theoretically it by comparison of the angle observation equations and the direction observation equations, and the proof holds any figure of triangulation and number of directions.抄録全体を表示PDF形式でダウンロード (568K) -
萩原 幸男1981 年 27 巻 1 号 p. 61-69
発行日: 1981/06/30
公開日: 2010/09/07
ジャーナル フリーPhysical meaning of the Bouguer reduction is reconsidered with respect to the vertical gradient of gravity anomaly. An iterative method is proposed for deriving the sealevel Bouguer anomaly and its vertical gradient from the conventional Bouguer anomaly at ground level. Actual computation results from gravity and topographic data of mountainous areas remind us of the significance of vertical gravity gradient for reducing the Bouguer anomaly to sealevel.抄録全体を表示PDF形式でダウンロード (1961K)
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