巻号一覧
21 巻 (1968)
- 4 号 p. 259-
- 3 号 p. 169-
- 2 号 p. 89-
- 1 号 p. 1-
前身誌
21 巻, 1 号
選択された号の論文の9件中1～9を表示しています
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田治米 鏡二, 岡田 広1968 年 21 巻 1 号 p. 1-13
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーFollowing the previous papers [TAZIME (1966)], conformal mappings of group velocity U on frequency ω-plane are obtained at first. Saddle points exist on curves where the imaginary part of U is zero, whereas the real part of it means x/t. AIRY-phase is seen on ω-plane. The locus of saddle points continues to run from AIRY-phase to one of singular points in the complex domain where group velocity is smaller than “the minimum group velocity”, resulting in the coda of a seismogram. Paths of the steepest descent from saddle points are also found on ω(-)-plane. Next, the amplitude function is shown on ω-plane. It must be noticed that the absolute value of the amplitude function in the complex domain is not always smaller than that on the real axis of ω-plane. Although imaginary parts of wave number and frequency are not zero, if they are small, amplitudes may become considerably large in the complex domain. The present authors think that “organ pipe mode” named by GILBERT (1964) cannot play an important role in LOVE waves, but does in dispersive RAYLEIGH waves in layers having large POISSON'S ratio.抄録全体を表示PDF形式でダウンロード (857K) -
入山 淳1968 年 21 巻 1 号 p. 14-20
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーThe internal structures of Venus, Marss, and the asteroid are examined in the light of the thermal state. The angular velocity of rotation, surface magnetic field strength, and C/Ma2 are used as constrained conditions.
Results of calculations show that the model terrestrial planets with chondritic composition are consistent with the above constrained conditions, provided that the smaller the size of planets is, the lower the initial temperature is.
The internal structure of Venus is similar to that of the earth. From the thermal structure and the slow rotation, the initial temperature within Venus is about 300-400deg. higher than that of the earth.
The initial temperature of Mars should be below 600°K, provided that Mars is free of the metallic core.
The asteroid must have an iron core, a mantle, and a crust, provided that the initial temperature throughout within the asteroid was above 1, 300°K.抄録全体を表示PDF形式でダウンロード (572K) -
平面 Love 波小口 雄康, 竹内 均1968 年 21 巻 1 号 p. 21-31
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーThe dispersion of plane Love waves in a transversely isotropic heterogeneous medium is studied. For arbitrary anisotropic factors, phase velocities, group velocities and partial derivatives of the phase velocity with respect to changes of the physical parameters of the medium are obtained by integrating directly the equation of motion and variational method of energy equation as used in the calculation of dispersion of surface waves in the isotropic heterogeneous earth. These values are calculated for the CANSD model of anisotropic factor ξ=1.2, 0.8 and 1.0 (isotropic case). It is shown from these calculations that the present methods are as useful for the anisotropic medium as for the isotropic one.抄録全体を表示PDF形式でダウンロード (852K) -
渡辺 晃, 中村 正夫1968 年 21 巻 1 号 p. 32-53
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーCrustal structure in the southwestern region of Kinki District, Central Japan, was studied in some detail by using travel-time data obtained from the third observation of ultra-microearthquakes and the routine observations of microearthquakes in and near this region.
During the observation period, about two thousand shocks were observed at the observation stations spread widely over Kinki District. Among them about one hundred shocks, whose hypocenters were determined with satisfactory accuracy in interpretation of travel-time data, were selected for the determination of apparent velocities in the upper crust.
The main results of the observations and their analyses are summarized as follows:
(1) A structure with three-layer crust was proposed for this region on the basis of travel-time data. The velocities of P waves and the average thicknesses of the layers were estimated to be 5.5km/sec and 5km for the first layer, 6.0km/sec and 10-15km for the second layer and 6.7km/sec for the third layer respectively. (The thickness of the third layer could not be estimated for lack of data on the upper mantle.)
(2) The thickness of the first layer, however, should be modified from place to place in this region, according to deviations of apparent velocities from the mean velocity of 5.5km/sec for the first layer. With suitable modification, it was ascertained that the thickness of the first layer increased continuously with distance from the central mountain region in Kii Peninsula.
(3) Comparison of the velocities on both sides of the Median Dislocation Line suggested the existence of a thick upper layer on the north side and a rather thin layer on the south side.
(4) In order to explain a remarkable deviation of apparent velocities in the vicinity of Wakayama and Hidaka, a low velocity layer might be added on the first layer in these regions, but its average thickness will be merely 1km or less, if its velocity is assumed to be 4.3km/sec, according to the YOSHIZAWA'S experiment (1955).
(5) On the south side of the Median Dislocation Line, anisotropy in the velocity of P waves was observed (higher velocity; along the line). And the value of anisotropy, decreasing rapidly with distance from the line, amounted roughly to 3-10%.抄録全体を表示PDF形式でダウンロード (1762K) -
尾池 和夫, 三雲 健1968 年 21 巻 1 号 p. 54-66
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーA multipartite seismometer array with a span of about 1km has been set up at one of the temporary stations for the observation of microearthquakes in Wakayama region, to examine the effects of local underground structure.
The apparent velocity and direction of wave approach for about 200 microearthquakes were determined by means of least squares from arrival times of P waves at 5 recording sites, as well as from the conventional tripartite technique. Parameters computed from 4 selected tripartite nets show systematic deviations from the results of least squares in relation to the azimuth. A possible explanation for the azimuthal dependence and for average travel-time residuals for each of the recording sites would be that there exists an upward-warping interface in the shallow portion of the crust. Several kinds of later phases can be identified on seismograms between the initial P and S waves. Their apparent velocities and travel-times appear to be consistent with the interpretation that these phases may be SV waves converted from incident P waves or vice versa at the above interface.抄録全体を表示PDF形式でダウンロード (1067K) -
竹内 均, 西川 正名1968 年 21 巻 1 号 p. 67-71
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーThere is an observational fact that the more strongly metamorphosed chondrites tend to have lower porosity and shorter (U, Th)-He ages. Furthermore the relation between S-wave velocity and confining pressure for crustal rocks give the idea that the porosity becomes very small at about 2-3kb. It is intended here to determine the size of meteorites parent body from these facts. The largest size thus determined is about 300-400km in radius.抄録全体を表示PDF形式でダウンロード (366K) -
関東大震災をめぐつて三好 寿1968 年 21 巻 1 号 p. 72-74
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (339K) -
堀 実1968 年 21 巻 1 号 p. 74-76
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (346K) -
佐藤 泰夫, 佐藤 良輔1968 年 21 巻 1 号 p. 76-78
発行日: 1968/05/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (282K)
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