巻号一覧
26 巻 (1973)
- 4 号 p. 305-
- 3 号 p. 223-
- 2 号 p. 107-
- 1 号 p. 1-
前身誌
26 巻, 3 号
選択された号の論文の10件中1～10を表示しています
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坂田 正治1973 年 26 巻 3 号 p. 223-229
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーThe actual crust is a rock system composed of numerous rock elements. Each rock element has its own strength and elastic coefficient. In order to discuss the occurence of an earthquake and the succeeding failure process it is important to consider the strength distribution and the elasticity distribution of a rock system.
In this paper a simple one-dimensional model of string-spring system which represents an actual earthquake with a reverse dip slip fault is discussed. Three types of basic failure process are got according to three types of strength distribution respectively. In case of the first and the second types there seems to be a period of relatively slow faulting movement which would not radiate any “ordinary seismic waves” before the steep movement which radiates “ordinary seismic waves”. Therefore these types have good possibility to explain the discrepancy between slip amplitudes derived from the geodetic survey data and the seismological data respectively in case of earthquakes such as the Great Kanto Earthquake or the Nankaido Earthquake. On the other hand in case of the third type there is no abrupt discharge of elastic strain energy.抄録全体を表示PDF形式でダウンロード (538K) -
中野 迪夫, 中村 孝一郎, 小林 直太, 竹内 均1973 年 26 巻 3 号 p. 230-240
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーWe measured bulk density and elastic wave velocities of composite materials, matrix and inclusions of which are epoxy resins and small iron balls, air bubbles and water drops, respectively.
Using the measured data, we calculated elastic constants and compared them with the Eshelby's theory on the elastic constants of composite materials.
We found that the agreement between the experimental and theoretical results are strongly effected by the shapes and distribution of the inclusions.抄録全体を表示PDF形式でダウンロード (2639K) -
小山 順二, 堀内 茂木, 平沢 朋郎1973 年 26 巻 3 号 p. 241-253
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーAn attempt is made to estimate regional earthquake generating stresses in the northeastern part of Japan. It is known from previous studies that mechanisms of earthquakes occurring in a small region are similar to one another, if the division of seismic region is appropriate. In virtue of this fact, we superpose all the data of initial motions of P-waves obtained from earthquakes that occurred in a subdivided region, and project them on the same focal sphere. The distributions of P-wave initial motions thus obtained are analyzed to determine the fault types, that is, normal faulting or reverse faulting.
The results obtained are summarized as follows:
1) Shallow earthquakes which occurred off the coast of Sanriku (west of 143.5°E and north of 38°N) are characterized by reverse faulting, while earthquakes in the ocean-side (east of 143.5°E and north of 38°N) are characterized by normal faulting.
2) Shallow earthquakes which occurred off the coast of Fukushima prefecture are characterized by reverse faulting, and no normal faulting can be found.
3) It is difficult to explain the initial motion pattern of P-waves from earthquakes beneath the trench (depth; 60-100km) by a normal-fault-mechanism.
4) Pressure axis is nearly parallel to the dip of the seismic plane (down dip compression) deeper than 110km in the north-eastern part of Japan.
5) Tension axis is approximately parallel to the dip of the seismic plane (down dip extension) for depths between 100km and about 60km.
6) No serious contradiction is found between the mechanism solution derived from the superposed data of many small earthquakes in a divided region and that from the data of a large earthquake in the same region.抄録全体を表示PDF形式でダウンロード (1087K) -
―2次元SH型の反射波, 先駆波に対して―山崎 謙介, 石井 紘1973 年 26 巻 3 号 p. 254-263
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーBy means of the change of integral variables and the Cauchy's theorem for complex integral, a reciprocal relation is verified for head and reflected waves in the theoretical seismogram from an SH line source in a dipping layer overlying an elastic solid, where in obtaining the theoretical seismogram we neglect contribution from diffracted waves from the top of the wedge.
The reciprocity does not hold for the waves which go back from the top of the wedge. This may be understood in connection with the waves which will arrive at a receiver later than head and reflected weves.
This reciprocal relationship is useful in the study of surface wave propagation in a wedge shaped medium. For example, theoretical and experimental seismograms for down-dip position of a source to a receiver can be obtained directly from the reversed case.抄録全体を表示PDF形式でダウンロード (699K) -
吉田 満1973 年 26 巻 3 号 p. 264-274
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーTime series of the ordinary seismic activity in Japan and the vicinity is statistically studied. The data are based on the hypocenter cards reported by JMA for the years 1961-1971. The data for the years with a large earthquake and an earthquake swarm were deleted so that the non-stationary process might not be introduced in the data. Under such a condition the monthly number of earthquakes fits the Poisson distribution P(n)=exp(-μ)μn/n! (μ is the mean value. n=0, 1, 2, …) in many regions in Japan and the vicinity. However the Poisson distribution can not be applied to the districts, Kumamoto, near Miyakejima, near Matsushiro where the earthquake swarm is apt to occur, and time series of the number of earthquakes from which aftershocks were not deleted completely do not fit well the Poisson distribution. The distribution of the number of earthquakes during the years 1961-1971 before the occurrence of Tokachioki earthquake (M=7.9, 16 May, 1968) fits the Poisson distribution in the rigion off Sanriku. In the ordinary seismic activity the monthly number of earthquakes is the highest at Boso Peninsula and the lowest at the districts facing the Sea of Japan.抄録全体を表示PDF形式でダウンロード (902K) -
古沢 保, 入倉 孝次郎, 赤松 純平1973 年 26 巻 3 号 p. 275-284
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーSeismic waves from local small earthquakes occuring in the southern parts of Kyoto were observed at the Amagase Crustal Movement Observatory and at Kameoke City, and spectral densities of P-waves were analyzed.
Magnitudes of analyzed events are in the range from 1.0 to 2.5. Peak frequencies of spectra seem to depend mainly on location of source, that is, peak frequencies of P-waves from events in the region where microearthquakes occur concentratedly, were lower than those from events in another region where seismic activity is very low. These observed results suggest that regional variation of physical properties such as strength and shear modulus exists in the crust.抄録全体を表示PDF形式でダウンロード (717K) -
羽鳥 徳太郎1973 年 26 巻 3 号 p. 285-293
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーMaking use of tide gauge records, the tsunami generated off about 100km east of Hachijo Island on Dec. 4, 1972 is investigated and its behavior is compared with the tsunami generated approximately in the same region on Feb. 29, 1972. The average wave height of the present tsunami is about 1.4 times as large as that of the tsunami in February 1972 and tsunami magnitude is determined as m=1 in accordance with the author's method.
The estimated tsunami source lies to the southwestern side of the 1953 Boso-oki tsunami source, including that of the tsunami in February 1972. The source area extends about 80km in the NE-SW direction. Judging from the initial motion of tsunami, the subsidence of the sea-bottom seems to have occurred in the west side of the tsunami source, and the upheaval in the east side. The features of the initial motion of tsunami were mostly similar to that of the tsunami in February 1972, i. e. the recorded initial motion of tsunami was downwards to southwestern Japan and upwards in northeastern Japan. By applying the corrections for the refraction and shoaling from the observed initial wave, the bottom deformation in the tsunami source would be occurred in the range of -5 to 8cm.
Remarkable gap lies between the 1923 Kanto and the 1953 Boso-oki tsunami source areas located along the Sagami trough. It should be noted to the Genroku tsunami of 1703 (m=2 or more) which might be generated in the vicinity of Boso peninsula.抄録全体を表示PDF形式でダウンロード (719K) -
笠原 順三, 大内 徹, 柳沢 馬住, 南雲 昭三郎1973 年 26 巻 3 号 p. 294-300
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (2083K) -
竹内 均1973 年 26 巻 3 号 p. 300-301
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (216K) -
阿部 司1973 年 26 巻 3 号 p. 301-303
発行日: 1973/11/30
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (249K)
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