巻号一覧
42 巻 (1989)
- 4 号 p. 405-
- 3 号 p. 271-
- 2 号 p. 151-
- 1 号 p. 1-
前身誌
42 巻, 4 号
選択された号の論文の15件中1～15を表示しています
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筒井 智樹, 小林 芳正, 芝 良昭, 須田 佳之, 村井 芳夫, 岩田 知孝, 藤原 広行, 松井 一郎1989 年 42 巻 4 号 p. 405-418
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーShallow subsurface structure around Hino River in the south-east shore of Lake Biwa was investigated by means of seismic reflection survey. The target area on the western margin of a seismic quiescent zone between the lake and the Suzuka range includes a belt of steep gradient of Bouguer anomaly which inclines west.
Survey lines were designed, one on the east and another on the west of Hino River, in order to determine the subsurface structure beneath the steep gradient belt of gravity. Time sections were constructed by the Common Depth Point (CDP) method and followed by the frequency-wavenumber (F-K) migration to discuss the subsurface structure in detail.
In the time sections of two survey lines, a horizon “A”, which is smoothly continuous, and another horizon “B”, which is inclined to south-west are recognized. The “A” horizon is considered to be a reflective plane in the Biwako-group, Quaternary deposits, by referring to the deep drilling log available in the neighborhood of the survey line. The “B” horizon is inferred to be an uncomformity boundary between the Biwako-group and the basement rocks because no continuous reflector can be found thereunder. Since the “B” horizon exibits a buried valley in the center of the western survey line and an south-westward inclination through the eastern survey line, this structure may be a remnant channel which used to run SE to NW during the erosive period of this area.
It is noticeable that the “A” horizon shows onlap boundary relation against “B” horizon in the center of the eastern survey line. This suggests that this area turned into subsidence after the erosive period.
No active faults were found above the “B” horizon through this survey. Hence low seismicity around the target area is likely inherent in character.抄録全体を表示PDF形式でダウンロード (2932K) -
佐藤 魂夫, 中山 耕治, 田中 和夫, 長谷見 晶子1989 年 42 巻 4 号 p. 419-437
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーP wave arrival times from 119 local events recorded by a dense network of seismograph stations located on northern part of the Tohoku district, Honshu, Japan, are inverted to determine lateral variations in crust and upper mantle structure to a depth of 230km. The maximum velocity difference in each layer decreases with increasing depth, from 18% in the first layer (0-12.5km) to 5% in the sixth layer (131-164km). In the uppermost layer (0-12.5km), we find low-velocity zones beneath the Tsugaru Plain, Noshiro Plain, and Akita Plain where quaternary sediments are thick. The second layer (12.5-32km) is marked by a high-velocity zone along a part of the Pacific Coast. This zone coincides with the zones of both positive geomagnetic anomalies and positive Bouguer gravity anomalies reported by other workers. In the uppermost mantle layer (32-65km), we find low-velocity zones beneath the active volcanoes near the volcanic front. Since this relationship has already been found for the central and southern parts of the Tohoku district, the present study shows that the same relationship holds over a wide area of the Northeastern Japan arc. In contrast, no conspicuous low-velocity zone is found beneath Mount Iwaki, an active volcano located 80km west of the volcanic front. High-velocity zones in the uppermost mantle layer extend over areas along the coastal lines of both the Pacific Ocean and the Japan Sea. This is in good agreement with the regional variation of Pn velocity estimated from explosion seismic data previously.
Cross-sectional projection of the velocity perturbation along east-west profiles shows a high velocity zone extending parallel to the inclined seismic zone of intermediate focus earthquakes. This high velocity zone is interpreted as the subducting Pacific plate. The fine structure in and around the inclined high velocity zone appears to differ regionally along the strike of the island arc, though its reliability must be confirmed in further elaborate inversion. We compare this regional variation of velocity structure with the seismicity of intermediate focus earthquakes, and find no clear correlation between them.抄録全体を表示PDF形式でダウンロード (3039K) -
富澤 稔1989 年 42 巻 4 号 p. 439-449
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーA trial of looking for physical meanings of the statistical time-series model fitted to the seismogram is described. This paper shows that if a particle movement of the elastic displacement field of the Earth due to White-noise body-force equivalent to stochastic displacement discontinuity on the seismic fault plane is observed at the ground surface, the observed wave-form corresponding to the seismogram can be expressed by the innovations representation for time-varying autoregressive moving-average process i. e. the time-varying ARMA model.
As briefly concluding remarks: (1) AR-coefficient matrices of the model can be interpreted as a function of eigen values of vibration of the Crust. (2) MA-coefficient matrices of the model are interpreted as a function not only of the eigen values but also of eigen-functions of vibration of the soil deposits under the observation site and of covariance function of the White-noise body-force. (3) Covariance function of the innovation sequence obtained from fitting the optimal time-varying ARMA or AR model to the digitalized seismogram has mainly relation to the covariance function of the White-noise body-force and also is influenced by both of the covariance functions of filtering and measurement errors.抄録全体を表示PDF形式でダウンロード (1128K) -
力武 常次1989 年 42 巻 4 号 p. 451-466
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーAnomalous phenomena precursory to the 1891 Nobi earthquake of magnitude 8.0 are collected mostly based on the existing results of the enquiry investigation conducted soon after the earthquake. Precursor data amounting to 202 in number become available along with their precursor times. They are rumbling or detonation, anomalous animal behaviour, earthquake light, changes in underground water/hot springs and so on.
It appears that the number of earthquake precursor tend to increase at about 100 days before the main shock. About 10 days preceding the shock, the increasing rate becomes much accelerated reaching a frequency peak having a precursor time of 1 day or so. Such a tendency of precursor appearance is much the same as that for the 1923 Kanto, 1944 Tonankai and 1978 Izu-Oshima Kinkai earthquakes although slight differences may be observed. The tendency that the number of precursor decreases as the distance between the epicenter and an observation spot increases is also confirmed.
In light of these precursors detected by human sense in association with the Nobi earthquake as well as other large earthquakes in Japan, attention should be paid to precursors of this class along with geophysical precursors in future earthquakes.抄録全体を表示PDF形式でダウンロード (1661K) -
羽鳥 徳太郎1989 年 42 巻 4 号 p. 467-473
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーThe Pacific coast of Japan has often suffered severe damage by distant tsunamis propagated from the circum Pacific regions (Chile-Peru, Kurile-Kamchatka and Aleutian-Alaska). Based on the historical documents or tide-gauge records observed in Japan during the period of about 400 years, 1586-1988, the geographic distribution of cumulative tsunami energy, ∑H2 for each 150km segment along the coast is investigated. The energy distribution for the distant tsunamis is compared with that of the near tsunamis which were generated in the vicinity of Japan. The obtained results are as follows:
1) The amount of cumulative energy, ∑H2=51m2 from the Chile-Peru tsunamis is largest at the Sanriku region, northeastern Japan.
2) The tsunami energy from the Kurile-Kamchatka reaching East Hokkaido and Sanriku regions is large, but the amount of energy is about one-third of that of the Chile-Peru tsunamis.
3) The energy from the Aleutian-Alaska and Philippine-Indonesia tsunamis is relatively small because of the effect of directivity.
4) The pattern of energy distribution for the distant tsunamis is different from that for the near tsunamis generated around Japan. Percentage of the energy from the distant tsunamis reaching SW. Hokkaido, Fukushima, Ibaraki and Okinawa is about 50% of the total tsunamigenic energy.抄録全体を表示PDF形式でダウンロード (699K) -
―断層の不均質性とfmax―小山 順二, 原 啓明1989 年 42 巻 4 号 p. 475-484
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーA theoretical study is made on the earthquake source spectrum for heterogeneous faultings with self-similar fault patches. The source spectrum of this fractal fault patch model is not so simple as that of the standard ω square model. It shows a frequency dependence of ω0-ω-2-ω-δ-ω-2+γ/2-ω-2, where δ is about 1 and γ is the fractal dimension of self-similar fault patches. γ takes a value in between 0 and 2. The spectrum demonstrates three characteristic corner frequencies, where the spectral envelope changes its trend. They corresponds to the rupture times of whole fault length, maximum fault patch, and minimum fault patches. The first is corner frequency well-known in long-period seismology. The second is understood as patch corner frequency. The third would be the cut-off frequency of fmax in the acceleration spectra.抄録全体を表示PDF形式でダウンロード (1206K) -
伊藤 潔, 村上 寛史, 中村 佳重郎1989 年 42 巻 4 号 p. 485-495
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーGravity measurement was carried out at more than 200 stations with LaCoste-Romberg gravimeters in the vicinity of the Arima-Takatsuki Tectonic Line, a prominent fault system in the northern Kinki district, central Japan. The areas with low Bouguer anomalies derived from the measurement correspond to sedimentary planes and basins, while areas of high Bouguer anomalies to the mountainous areas. The areas of steep horizontal gradients of the Bouguer anomaly lie along active faults developed in the district. In particular a line of steep gradient of the gravity anomaly is seen along the Arima-Takatsuki tectonic line, which also correspond to the boundary between the sedimentary plane by the Yodo River and the outcropped area of the Tanba zone. Most of changes in the Bouguer anomalies are explained by that of the thickness of the unconsolidated sedimentary layer of about 1km. The seismic activity in the area however is clearly bounded by the Arima-Takatsuki tectonic line; in its northern part the seismicity is very high, while in the southern part a few earthquakes occur. This suggests that the fault movement at the depth of the earthquake occurrence, 5 to 15km is concerned to the variation of the thicknesses of the sedimentary layer. A line of a weak horizontal gradient of the gravity anomaly is detected along a clear boundary of the seismicity which is located along the Inagawa river striking northwest to southeast. This implies a deep embedded fault in the area, though the boundary does not corresponds to any confirmed active faults.抄録全体を表示PDF形式でダウンロード (1242K) -
その1 世帯に及ぼす影響の時間変動性-記載法-太田 裕, 岡田 成幸1989 年 42 巻 4 号 p. 497-506
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーDespite that earthquake disasters and regarded phenomena vary their characters and aspects in time on damage and restoration processes, no many studies have yet been made as natural as they are. This paper attempts a development of the methodology by which all of major earthquake phenomena in dynamic manner can well be described.
Paying special attention to a household, a fundamental unit in our human society, the authors develop a model which considers the total seismic effect in terms of “time variation in the living standards of a households” after an earthquake. The living standards and its change in time, under the critical situation attacked by an earthquake, can be described by a combination of four major factors regarding physical, commodity, family and economic damages. Damages to dwelling and lifeline facilities are significant elements in the physical factor. Commodity factor relates to the shortage of foods, water and other daily goods. Representative elements in the family factor are casualties of the family members. Extraordinary expenses for the reconstruction of a dwelling is an important element in the economic factor. The household's living standards in the quantitative sense can be defined as an integration of the seismic effects in terms of those factors of which characteristics are expressed and evaluated in time-dependent functional forms.
In the following paper, a case study of the time-varying household's living standards for a large city in Japan will be demonstrated based on the developed methodology.抄録全体を表示PDF形式でダウンロード (1795K) -
田中 愛一郎1989 年 42 巻 4 号 p. 507-512
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (458K) -
伊東 和彦, 松島 昭吾1989 年 42 巻 4 号 p. 513-515
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (301K) -
―4衛星運航下における基線決定の再現性―木股 文昭, 中村 勝, 奥田 隆, 宮島 力雄, 角野 由夫, 里村 幹夫, 佐々木 祐治, 佐々木 嘉三1989 年 42 巻 4 号 p. 517-520
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (393K) -
鈴木 保典1989 年 42 巻 4 号 p. 521-524
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (377K) -
松澤 暢1989 年 42 巻 4 号 p. 525-536
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーMany later phases such as ScSp, PS, SP and SS converted or reflected at the upper boundary of a descending oceanic plate are frequently observed in a subduction zone. The location of the upper boundary has been estimated to be just above the deep seismic zone by the use of these phases. Moreover, from the analyses of the later phases such as PS and channel waves, it has been found that a low velocity layer exists on the surface of the plate. The most probable interpretation of the low velocity layer, at least in the shallow depths, is the descending oceanic crust.抄録全体を表示PDF形式でダウンロード (1775K) -
坪井 誠司1989 年 42 巻 4 号 p. 537-549
発行日: 1989/12/24
公開日: 2010/03/11
ジャーナル フリーThe elastic waves propagating on the earth can be modeled completely by the sum of normal modes, or the free oscillations of the earth. As a result, the free oscillations of the earth have been used as an useful tool for the study of both earth structure and earthquake source mechanisms, after they had been first observed in the great Chilean earthquake of 1960. In 1980s, with the development of recent global digital seismograph networks, it has become possible to obtain laterally heterogeneous earth structure using the observation of the surface waves or the free oscillations. In the present paper, we will try to review the recent progress in the technique for the analysis of the free oscillations of the earth to obtain laterally heterogeneous structure.抄録全体を表示PDF形式でダウンロード (1729K) -
1989 年 42 巻 4 号 p. 551
発行日: 1989年
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (32K)
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