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, 3 号
選択された号の論文の11件中1～11を表示しています
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梅田 康弘1968 年 21 巻 3 号 p. 169-177
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーThe Matsushiro earthquake swarm gave us a chance to study the attenuation of seismic waves in short hypocentral distances.
During the observation periods (Jun. 1966-Aug. 1966 and Nov. 1966-Mar. 1967), four and five observation stations were temporarily arrayed along two lines which were respectively oriented toward the southeast and southwest directions from Matsushiro, so as to be parallel to nodal lines derived from the quadrant type pattern of initial P waves. At each station, we installed a horizontal seismograph having a natural period of 0.6 sec to be sensitive perpendicularly to the observation line. Magnification of the seismographs ranged from 50 to 135 according to the distances from Matsushro in order to prevent going off scale or disturbances of background noises on recording.
In the present study, attenuation of maximum amplitude with distance is mainly treated and a result of analyses shows that the maximum amplitude observed at each station along the observation array does not monotonously decrease with focal distance, but it abruptly increases at distances between about 30km to 40km and again decreases steadily beyond this range. The ratio of the mximum amplitudes at distances of about 40km to about 30km is averagely 1.4, and accordingly the attenuation coefficient should be determined for both of the two ranges.
By use of recordings of fifty three shocks, the attenuation coefficient h in the equation A=A0/r·exp (-hr) was calculated and its average value was 0.059km-1 for the range of r<30km, where r is the hypocentral distance and A is the maximum amplitude. The value of h for the range of r>40km was also estimated to be 0.047km-1, though with doubtful accuracy due to the lack of data. According to these observed data and Richter's definition of magnitude, we were able to derive the following equation among magnitude M, hypocentral distance r in kilometer and maximum amplitude A in micron.
M=logA+logr+0.026r-0.19 for r<30km
M=logA+logr+0.020r-0.59 for r>40km.抄録全体を表示PDF形式でダウンロード (708K) -
小林 芳正1968 年 21 巻 3 号 p. 178-189
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーThis study is intended to clarify the mechanism of earthquake damage to embankments and slopes. Mechanisms, including 1) sliding of a mass, 2) collapse of an embankment, 3) failure of a slope of cohesive and of non-cohesive materials, 4) fissures on an embankment, 5) settlement of an embankment and 6) phenomena related to liquefaction of soil, are studied referring to examples of actual damage of the type. Sliding of a mass can most appropriately be explained by the block sliding theory by NEWMARK. The collapse of an embankment may also be explained by the theory with a little modification in the assumption for mechanical properties of soils. The mechanism of failure of a cohesive material is essentially the same as that of 1) or 2); that of a slope of a cohesionless material is, however, different and is correlated with the acceleration of the ground motion. The fissures on an embankment can be divided into three groups which are connected with either sliding or displacement of a part adjacent to the slope of the embankment or a local subsidence of the embankment. The settlement of an embankment occurs in regions of earthquake intensity of higher half of IV to V in the J. M. A. scale. In case of liquefaction of soils, flow of materials of an embankment as a liquid or subsidence due to decrease in volume of an embankment or an underlying layer may occur.
One of the most important factors which may influence the damage is the unbalance of acting forces due to the gravity, and the resistance to failure decreases noticeably with increase in inclination of the slope of an embankment or a cutting. The change in mechanical properties of soils during vibration or failure is another important factor for the damage and it should be taken, in general, into consideration to understand the damage. The number of effective pulses for damage is also important in estimating the extent of the damage. The number is estimated in the paper as 7-40 or moreover based on considerations on the mechanism of the damage or seismograms of destructive earthquakes.抄録全体を表示PDF形式でダウンロード (1082K) -
池上 良平1968 年 21 巻 3 号 p. 190-201
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーThe writer tried to find out whether any secular variations occur in the value of β in the expression of relation between the number N of earthquakes and their magnitude logΔ, log N=α-β logΔ, using, in place of magnitude M, the value logΔ, a common logarithm of the maximum felt distance of the earthquake.
In the previous paper Regions A and B in Fig. 1 were treated, and in the present paper Regions C and D in same figure are treated.
The maximum felt distances, Δ, of the earthquakes occurred in these regions were sorted out for the years 1925-1966 and were divided into four groups: Δ=150km (100km≤Δ<200km), 250km (200km≤Δ<300km), 350km (300km≤Δ<400km) and 450km (400km≤Δ<500km). With regard to the number N of earthquakes during the period of every seven years, the coefficients α and β in each region were determined by the method of least squares.
The obtained values of α and β are shown in Table 3, together with their probable errors, and the variations of the value of β are shown in Figs. 3a (Region C) and 3b (Region D), respectively. From these diagrams it is certain that the value of β in each region shows secular variation as the previous results in regions A and B. On the abscissae of these diagrams the arrows show the years for which the annual seismic energy exceeded about 1022 ergs, and it is noticeable that release of great seismic energy took place when the value of β was becoming minimum.抄録全体を表示PDF形式でダウンロード (836K) -
低速度層を中心に角田 寿喜1968 年 21 巻 3 号 p. 202-221
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーDiscontinuities of S travel time curves in the earthquakes, that occurred off east coast of Hokkaido and near the Kurile Islands, are observed at an epicentral distance of about 10 degrees. The most probable cause of this phenomena is thought to be a low velocity layer.
In the case when a low velocity layer exists, the Herglotz-Wiechert method cannot be applied to below the uppermost part of the low velocity layer. Many trials have been made to supply the deficiency of this method, but there has never been a complete methcd in the principle.
In this paper, the author gives a method to determine the velocity distribution of S waves in the upper mantle when a low velocity layer exists. This is the method of using the discontinuous points of S travel time curves.
The results are that the low velocity layer for S waves in this area begins at a depth of about 50km having a velocity minimum at about 150km, and that S wave velocity decreases gradually from the neighborhood of the Mohorovicic discontinuity to the low velocity layer.
The quantitative results are not satisfactory because of incompleteness of data, but the pattern of this velocity distribution seems trustworthy.抄録全体を表示PDF形式でダウンロード (1633K) -
笠原 順三, 鈴木 功, 熊沢 峰夫, 小林 洋二, 飯田 汲事1968 年 21 巻 3 号 p. 222-228
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーCompressional wave velocity and the preferred orientation of olivine of Hidaka Horoman dunite (sample name HD 20 A) were measured. Fabrics of compressional wave velocity of the dunite and preferred orientation of olivine in the dunite are shown. These fabrics are closely related to each other. Olivine crystallographic “a” axis concentrated about the tectonic X axis. Maximum compressional velocity is 8.8km/s and minimum one is 7.9km/s.抄録全体を表示PDF形式でダウンロード (522K) -
笠原 順三, 鈴木 功, 熊沢 峰夫, 飯田 汲事1968 年 21 巻 3 号 p. 229-236
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーShear wave velocity of Hidaka Horoman dunite (HD 20 A) was measured. Fabrics of two shear velocities at same path, VSI, VSII, velocity difference, ΔVs=VSI-VSII, and particle motion are shown. These fabrics are closely related to fabrics of compressional wave velocity and preferred orientation of olivine. Maximum shear velocity is 4.86km/s and minimum one is 4.54km/s. Maximum velocity difference is 0.34km/s.抄録全体を表示PDF形式でダウンロード (1884K) -
長宗 留男1968 年 21 巻 3 号 p. 237-240
発行日: 1968/11/30
公開日: 2010/03/11
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大塚 道男1968 年 21 巻 3 号 p. 240-242
発行日: 1968/11/30
公開日: 2010/03/11
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2. ヨシュア記－詩篇尾崎 郁子, 佐藤 泰夫1968 年 21 巻 3 号 p. 243-246
発行日: 1968/11/30
公開日: 2010/03/11
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佐藤 良輔1968 年 21 巻 3 号 p. 247-248
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (254K) -
地球物理理論と計算機国際シンポジウム準備委員会1968 年 21 巻 3 号 p. 248-251
発行日: 1968/11/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (359K)
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