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, 2 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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避難人口・収容能力の変動と地震危険度の考慮太田 裕, 鏡味 洋史1981 年 34 巻 2 号 p. 161-174
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーIn the previous paper, a strategy for site planning of out-door refuge places in case of a large earthquake was formulated applying Linear Programing Method (Transportation Problem). In this method, refugee populations, capacities of refuge places and distance from refugee to refuge place, are required as known factors, in order to obtain optimal movements of residents in a given city. So it is most important to have precise estimations of these three values.
In this paper, an actural city with population of 1 milion is chosen as a test case to disclose a variety of problems behind these three factors. Through an investigation about this city, refugee populations and capacities of refuge places are estimated for various probable conditions. Distances from refugees to refuge places are reevaluated making much account of the spatial variations of seismic risk. Disposition and scale of the prepared refuge places in the city are checked by the proposed method and many points to be improved are indicated.抄録全体を表示PDF形式でダウンロード (1528K) -
―その必要性と試作―大塚 道男1981 年 34 巻 2 号 p. 175-187
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーAlthough dense networks of microseismic stations are spread over wide area of Japan for the purpose of forcasting disasterous earthquakes, it also is to be noted that still broader area is left unmonitored as regards their seismic activities. It is much more true when we talk the matter in the international sense.
To cope with the situation, a handy, compact and maintenance-free seismograph has been developed. The object is
a) to supplement the gap of microseismic observations,
b) to serve as a tool for teaching aids and
c) to facilitate mobile observations of seismic activity.
The basic idea and design of its development are described in some detail.抄録全体を表示PDF形式でダウンロード (3776K) -
友田 好文, 藤本 博巳1981 年 34 巻 2 号 p. 189-195
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーResidual gravity anomaly (R. G. A.) map in the northwest Pacific was made by use of sea gravity and seismic results.
R. G. A. proposed by YOSHII is powerful method to know density anomaly or tnickness anomaly of lithosphere.
R. G. A. results show that lithosphere becomes thicker towards the trench. This can be interpreted as driving force of subduction. It is difficult to determine details of it, because R. G. A. landward of the trench is not so clear.抄録全体を表示PDF形式でダウンロード (673K) -
橋本 学1981 年 34 巻 2 号 p. 197-211
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーA three-dimensional finite element method is used to simulate the observed stress state in the Southwestern Japan, which has been inferred by SHIONO (1977). Two different types of model are presented here, one is a locked model and the other is a decoupled model, where the former preserves a tight contact between the subducting Philippine Sea plate and the overriding continental plate, while the latter has a weak zone between them. In these models three different types of force are applied;
(1) a negative buoyancy due to the density contrast between the subducting plate and surrounding mantle,
(2) a northwestward compressional force generated by the movement of the Philippine Sea plate,
(3) a westward compressional force due to the subducting Pacific plate.
It is found that the observed extensional stress parallel to the leading edge of the subducting Philippine Sea plate may be caused mainly by a negative buoyancy, suggesting that the plate seems to sink down into the mantle by its own weight. The observed E-W compressional stress field prevailing in the Inner zone appears to be closely associated with the subduction of the Pacific plate. The northwestward horizontal compressional force may be smaller than the westward compressional force, and seems to be less than 500bars. The present calculations suggest that a low velocity layer between the oceanic and continental plates gives appreciable effects on low-angled thrust faulting off the Kii peninsula and the Shikoku island.抄録全体を表示PDF形式でダウンロード (1345K) -
日本列島の応力場見野 和夫1981 年 34 巻 2 号 p. 213-222
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーThe distribution of direction of horizontal and compressive stress acted upon Japanese Islands is investigated by analysing data composed of geographical heights. For analysis of topography expressed by geographical heights, theory of buckle folding is utilized.
The distribution of stress pattern derived from topography is very consistent with the conclusions estimated from static data such as geological or geodetic ones.
The distribution of direction of maximum compressive stress derived from analysis of topography indicates into E-W in whole Japan. But in the western part of Southwest Japan, the orientation of the compressive stress is distributed in nearly N-S direction. Reason of these difference may be thought of stress state in the upper part of the crust.
Earthquake and active fault are controled under the same stress above mentioned.
The topography has been produced by the stress during Quaternary period and it continues up to present.抄録全体を表示PDF形式でダウンロード (993K) -
森田 裕一, 浜口 博之1981 年 34 巻 2 号 p. 223-240
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーRecent increasing amount of microearthquake data requires urgent necessity of accurate automatic handling in on- and/or off-line processings. Although several techniques have been proposed for automatic detection of P arrivals, those for S onset times are still less developed. This is mainly because the signal to noise ratios around S arrivals are usually very low, in other words, the variations of amplitude and frequency are not so conspicuous as in the case of P waves. This paper aims to show a practical algorithm for the detection of S arrivals.
First, the particle motions of P and S waves are investigated based on the rotary spectra from two components of seismograms. It is found that the information of particle motions can improve noticeably the detection accuracies of P and S onset times and can be effectively used as a powerful tool of detection, especially when the signal to noise ratios are low. The direct usage of particle motion is too tedious to be adopted in practical automatic processing. It is proposed, therefore, to apply the 2-dimensional autoregressive model (AR model) to two horizontal components of seismograms. The parameters in this model, involve implicitly the information on amplitude and frequency as well as particle motion. An algorithm using the log-likelihood ratio function of 2-dimensional AR model is tested for actual microearthquake data. It is proved that 2-dimensional model based on two components of seismogram is much more powerful for the detection of S onset times than 1-dimensional one from a single component.
The differences between S onset times by eyes and computer are examined for data of which S-P times are from 2 to 30 seconds. They are within ±0.1 seconds for 43 (86%) out of 50 events and within ±0.15 seconds for 47 data (94%). The bias is 0.02 seconds, which is of no significance. This algorithm is practical available in off-line processing, although it needs too long computer time for real time one.抄録全体を表示PDF形式でダウンロード (1753K) -
楠瀬 勤一郎, 西沢 修, 伊藤 久男, 石戸 経士, 長谷川 功1981 年 34 巻 2 号 p. 241-250
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーAn attempt is made to elucidate the source mechanism of acoustic emission events which take place in granodiorite and andesite specimens under moderate uniaxial stress hypocenter determinations show that events were homogeneously distributed throughout the sample. The focal mechanisms indicated by the radiation of the first motion of the signals suggest, in some parts, shear crackings radiate acoustic emissions in the rock specimen.抄録全体を表示PDF形式でダウンロード (880K) -
―テレメータ観測による―鈴木 貞臣, 本谷 義信1981 年 34 巻 2 号 p. 251-267
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーThe seismicity in and near Hokkaido, Japan during the period from 1976 to 1980 has been studied by means of the telemeter observation system having nine high-gain seismograph stations.
The highest activity of shallow microearthquakes (0 to 60km depth) is in Pacific coast from the coast of Urakawa to east off the Shimokita peninsula. In northern part of this area great earthquake with M7 or greater has not occurred for 50 years. In southern part of this area the largest aftershock (M7.5) of the 1968 Tokachi-Oki earthquake (M7.9) occurred. Seismicities in the aftershock areas of the 1968 Tokachi-Oki earthquake and the 1973 Nemuro-Oki earthquake (M7.4) are inactive, while the number of microearthquakes in the aftershock area of the 1952 Tokachi-Oki earthquake (M8.1) has an increasing tendency since 1979. Teshikaga-Akan area of eastern Hokkaido, in which nine shallow earthquakes with magnitudes 5 or 6 occurred during the period from 1938 to 1967 shows low seismic activity during the period of observation.
The accurate location of microearthquakes in deep seismic zone shows two dipping zones 25-30km apart beneath the area from the southwest to the middle of Hokkaido. Beneath southern Hokkaido (the northern side of the Northeast Japan arc), the seismicity of the upper zone is more active than that of the lower zone, while beneath central Hokkaido (the western side of the Kurile arc), the seismicity of the lower zone is more active than that of the upper zone.抄録全体を表示PDF形式でダウンロード (1631K) -
鈴木 貞臣1981 年 34 巻 2 号 p. 269-272
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (493K) -
中村 一明1981 年 34 巻 2 号 p. 272-274
発行日: 1981/08/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (412K)
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