巻号一覧
34 巻 (1981)
- 4 号 p. 455-
- 3 号 p. 301-
- 2 号 p. 161-
- 1 号 p. 1-
- special 号 p. 1-
前身誌
34 巻, 4 号
選択された号の論文の12件中1～12を表示しています
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予測と異常検出の試み大内 徹, 高橋 亨1981 年 34 巻 4 号 p. 455-464
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーA new method for the analysis of non-stationary time series with trends is proposed. Integrated autoregressive models are used to eliminate the trend component. An adaptive procedure of fitting the non-stationary autoregressive models which is based on the concept of the local stationarity is applied for the identification of the stationarity of the data. This procedure enables us to divide the non-stationary data into several locally stationary series. This method is useful for the prediction of the future values and the detection of the change of the statistical properties in the data. Feasibility of this method is discussed and it is successfully applied to the series of the strain change, the ground tilt and the number of the earthquakes.抄録全体を表示PDF形式でダウンロード (760K) -
府中2,750m観測井における測定とまとめ山水 史生, 高橋 博, 後藤 典俊, 太田 裕1981 年 34 巻 4 号 p. 465-479
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーContinued to previous works at Iwatsuki and Shimohsa, S wave velocities in deep soil deposits were measured by using the observation well at the Fuchu Deep-Borehole Crustal Activity Observatory of the National Research Center for Disaster Prevention, Japan.
Measurements were conducted at 17 different depths to the borehole bottom with the depth of 2, 750m at intervals of 100-250m. S waves were excited by the SH wave generator on the ground surface. The excited waves were observed by a set of three component seismometers assembled into the specially designed capsule. The capsule can fix itself to the borehole wall at any depths.
The measurement revealed that the deposit at the Fuchu is fundamentally composed of three layers which covers the basement rocks. S wave velocities of those layers are, from the top to the bottom, 0.54, 0.78, and 1.19km/sec, and that of the substratum is 2.54km/sec. The velocity structure, including the P wave one, is consistent with such data as geologic section, sonic velocity, bulk density, and electric resistivity loggings of the observation well.
Through a comparison of thus obtained structures at three separate sites, Iwatsuki, Shimohsa, and Fuchu, one can visualize the underground structure three dimensionally, though vaguely and restricted in the Tokyo metropolitan area. A relation between the seismic wave velocity and the geological condition is also obtained. The relation is useful to estimate the velocity structure at deep-wells which were bored for the purpose of the geological investigation. Finally, it is found that the P wave velocity of the basement obtained from our direct method is rather small compared with the one from the refraction method. The difference is confirmed to be meaningful. It seems to be caused from the basement structure, that is, the basement is not uniform but has a thin layer at its top. The velocity difference between this layer and the lower basement is so small that the upper-most layer is masked in the ordinary refraction exploration.抄録全体を表示PDF形式でダウンロード (1533K) -
井元 政二郎, 唐鎌 郁夫, 松浦 律子, 山崎 文人, 吉田 明夫, 石橋 克彦1981 年 34 巻 4 号 p. 481-493
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーThe focal mechanisms of about 150 earthquake (M≥3.0), which occurred off the east coast of the Izu peninsula during the period from June 25 to July 28, 1980, are determined with P wave first motions observed at 61 stations in the Kanto and Tokai districts. The hypocenters are also determined with P wave arrival times. Most of them are located in a dipping planar zone with dip direction N75°E and dip angle about 65°. Some exceptional shocks, most of which occurred before the largest shock, are located in a steeper linear zone which crosses the plane obliquely in the northern part of the area. Most of the earthquakes are strike-slip type, where the number of earthquakes of dip-slip type is about one fourth. Strike of strike-slip faults seem to depend on its location. Earthquakes with a strike about N15°W shape the dipping plane mentioned above. On the other hand, those of a strike ranging N40°-50°W seem to belong almost to the steeper zone in the northern part. A systematic time variation in azimuth of tension axes is found, that is explained by a migration of active area and the regionality of strike of faults. The fault plane solution of the largest shock is slightly but surely different from the strike of the hypocentral distribution, N15°W.抄録全体を表示PDF形式でダウンロード (1271K) -
武尾 実, 阿部 勝征1981 年 34 巻 4 号 p. 495-504
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーUsing the near-field strong-motion records obtained at Usu and Matsushiro, Japan, we develop the technique for determining Richter's local magnitudes ML to earthquakes recorded at very short distances. To determine ML we use the integrated ground velocities and the amplitudes on the standard Wood-Anderson records which are synthesized from accelerograms. The present scale is intended to coincide with the scale used for local earthquakes in Japan, which is logically consistent with the original ML scale. The distance-correction term is determined over the epicentral distance from 0 to 20km. The newly obtained values are slightly different from the original values. The results can be applied to near-field accelerograms of earthquakes in California as well as Japan.抄録全体を表示PDF形式でダウンロード (985K) -
服部 定育, イブラヒム E. M.1981 年 34 巻 4 号 p. 505-519
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーEarthquake data in Egypt and its vicinity were compiled and arranged for the period B. C. 2200-A. D. 1978. The data earlier than A. D. 1900 were adjusted with reference to historical documents of earthquake disaster and the others (Period: 1901-1978) were arranged by consulting seismological bulletins of many observatories in the world and the seismological report of Helwan Institute. It was recognized from the above data that active seismic areas in and near Egypt were (1) Central part of Red Sea, (2) Northern part of Red Sea, (3) Levant region and (4) Northeast part of Egypt.
Seismic risk maps for the area concerned, that is, regional distributions of maximum earthquake motion for some return periods were drawn up making use of the aforesaid data, attenuation models and the method of extreme value fitting. The maps consist of the following two kinds; (1) The maximum particle velocity (kine) on the base rock and (2) the maximum acceleration (gal) on the ground. The return periods of these maps are 300 and 600 years, respectively.抄録全体を表示PDF形式でダウンロード (1293K) -
堀内 茂木, 増田 徹, 浅野 周三, 吉井 敏尅, 金田 義行, 岡田 広, 島村 英紀, 高波 鉄夫1981 年 34 巻 4 号 p. 521-533
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーIn October, 1978, sixteen explosions were carried out along a line 400km long at sea off Tohoku, Japan, where many large earthquakes have been occurring. Travel time of first arrivals of seismic waves from these explosions are used to evaluate the accuracy of hypocenter determination. Locations of shot points are computed by using arrival time data observed only at stations of the seismic network of Tohoku University and estimated location of shot points east of the seismic network between 38°N to 40°N is close to real shot points. The difference is less than 15km. However, estimated shot points northeast and southeast of the seismic network is far from real shot points. The largest value of the shift reaches 130km. To simulate hypocenter determination of earthquakes for which both P and S arrival times are used, origin times are restrained in the hypocenter determination of the explosions. In this case, the hypocenters for explosions north of 40°N and south of 38°N are more acculately located. Taking into account the lateral heterogeneity of the velocity structure of the crust and the uppermost part of the mantle, the hypocenter determination is improved to some extent, though improvement is small.抄録全体を表示PDF形式でダウンロード (1352K) -
堀家 正則1981 年 34 巻 4 号 p. 535-550
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーIn order to invert phase velocities of transverse component of microtremors for S-velocity structure of soil deposits, array observations of two perpendicular horizontal components as well as vertical one were carried out in the reclaimed land of Ogura-Ike pond. Phase velocities of three components were derived from frequency-wavenumber spectra for each component. The results obtained are as follows. (1) All the three components of microtremors come from N24°W direction. This suggests that most sources of microtremors are distributed in the Kyoto city area. V-component is composed of Rayleigh waves and T-component of Love waves. It is likely, however, that microtremors for each frequency are composed of plural modes rather than single mode, especially for frequencies higher than about 3.0Hz. Since it is difficult to identify the mode to which the velocity obtained belongs, the phase velocity of T-component may not be useful for S-velocity inversion. (2) Phase velocities of T- and R-component are nearly equal. For frequencies higher than 3.5Hz, power spectra of T-component are almost always larger than those of R-component and for frequencies lower than 3.5Hz, it is not always the case. (3) As a result of comparison between phase velocities of R- and V-component, they are found to be different unexpectedly.抄録全体を表示PDF形式でダウンロード (1387K) -
地殻構造を考慮した計算結果に基づく里 嘉千茂, 石井 紘, 高木 章雄1981 年 34 巻 4 号 p. 551-563
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーSeismic activity and crustal movement in the northeastern Japan arc seem to arise from the mutual action between the continental plate and the Pacific Ocean plate. It is, therefore, very interesting and important to investigate numerically the spacial distribution and the time variation of the crustal stress and the crustal movement caused by the subducting plate.
We apply a two-dimensional finite element method to estimate the stress field and the displacement field by use of the crust and upper mantle structure precisely determined by explosion seismology, and compare the results with the observed facts. The lower crust and the upper mantle are assumed to be viscoelastic materials, considering such facts as much lower seismic activity in these layers than in the upper crust beneath the land and the existence of migrating shear strain.
The numerical computation is carried out for two types of boundary condition. One is that a normal stress of 100bars is given to the Pacific Ocean side, and the other, a shear stress of 100bars is given along the boundary of two plates.
It is found that the stress produced in the crust is almost E-W compressional regardless of boundary condition in good agreement with the results of earthquake mechanisms and crustal movement observations. It is striking that the stress in the upper crust becomes much larger with time than that in the lower crust and upper mantle, corresponding to such facts as the high seismicity of the former and the lower seismicity of the latter. It is clarified that for the shear stress boundary condition a remarkable subsidence and a slight uplift are characteristic at the coast of the Pacific Ocean and at the coast of the Japan Sea, respectively. It is also made clear that horizontal movements are towards west having larger displacement in the Pacific Ocean side than in the Japan Sea side. These computed results are in harmony with observations. It is revealed that the distribution of crustal stress is closely related to the changes of crustal structure, leading to the recognition that the precise determination of the crustal structure is of very importance.抄録全体を表示PDF形式でダウンロード (1276K) -
池田 隆司, 高橋 博1981 年 34 巻 4 号 p. 565-576
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーUsing the hydrofracturing technique, in-situ stress measurements have been made in a 450-m-deep well drilled through silty mudstone (the Miocene). Stress has been measured at ten points between depths of 101 and 437m.
Data show a steady increase with depth for both maximum (σH max) and minimum (σH min) horizontal compressive stresses, from 33 to 136 bars, and from 20 to 85 bars, respectively.
A borehole televiewer and an impression packer are used to detect new fractures created by the hydrofracturing, which indicate the azimuth of σH max. The impression packer detects new fractures more clearly than the borehole televiewer. The direction of σH max is N45°±10°W. This direction does not agree with those estimated from joints which have been developed in the Neogene formations (the maximum compressive stress axis is N-S or vertical), and tectonic strain analyzed from the first order triangulation survey (the maximum compressive strain axis is N-S). But the hydrofracturing result agrees well with the nothwestward motion of the Philippin Sea plate relative to the Asian plate.抄録全体を表示PDF形式でダウンロード (2455K) -
佐藤 裕1981 年 34 巻 4 号 p. 577-587
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーTemporal variation in the rate of ground uplift in the Izu Peninsula is investigated minutely using the data of daily mean sealevel at the tidal stations of Ito, Aburatsubo and Manazuru, located along the coast of the Sagami Bay. The following relations between the ground uplift and seimic activity are found in commom in the four recent seismically active periods in Izu, that is,
1) The seismic activity was preceded several months by the ground uplift.
2) The rate of the grouud uplift was nearly constant, scarcely affected by occurrence of earthquakes
3) The ground uplift ceased at the nearly same time of decay of the seismic activity. These facts may give an important clue to elucidate the mechanism of the recent seismic activity in the Izu Peninsula.抄録全体を表示PDF形式でダウンロード (899K) -
山水 史生, 高橋 博, 太田 裕, 後藤 典俊, 武山 孝夫1981 年 34 巻 4 号 p. 589-591
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (387K) -
藤井 陽一郎1981 年 34 巻 4 号 p. 591-593
発行日: 1981/12/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (241K)
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