巻号一覧
37 巻 (1984)
- 4 号 p. 523-
- 3 号 p. 357-
- 2 号 p. 163-
- 1 号 p. 1-
前身誌
37 巻, 1 号
選択された号の論文の17件中1～17を表示しています
- |<
- <
- 1
- >
- >|
-
平岩 幸雄1984 年 37 巻 1 号 p. 1-12
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーThe relationship between swarm activities on Izu Peninsular and its neighboring area and the possibility of an earthquake occuring afterward is irregular, and at present we cannot predict when a strong earthquake will occur. We have studied earthquakes of M≥5. 8 that occurred in this district and obtained the following relationship:
Y=-40±0.9X
Where X is a comparison value between the starting day of swarm activities and a calculated day when an earthquake M≥6 is expected to occure after a destructive earthquake, and Y is a comparison value between the starting day of swarm activities and the day when an earthquake of M≥6 actually occured.
When “X” is a negative value, it is calculated using the negative sign.
When “X” is equal to ±44, “Y” becomes zero. In other words, if the comparison value between the starting day of swarm activities and calculated value (day) of an earthquake of M≥6 is ±44 (days), a strong earthquake (M≥5.8) would occur immediately after the first day of the swarm activities.抄録全体を表示PDF形式でダウンロード (1071K) -
井元 政二郎1984 年 37 巻 1 号 p. 13-22
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーHypocenters, focal mechanisms and magnitude-frequency relations were studied in detail for a swarm activity which took place off east coast of the Izu Peninsula, central Japan, in January 1983. Hypocenters were restricted in a small source volume of a few kilometers in diameter. Most of the focal plane solutions present strike-slip type with the maximum pressure axis in the NW-SE direction, that is consistent with the tectonic stress field. At the beginning of the swarm activity, b value was larger than the value before the swarm (normal value). It decreased with time corresponding to activation of seismicity. After the largest shock (MJMA=4.5), b value increased exceeding the value at the beginning, and finally it resumed the normal value. This characteristic pattern of the variation in magnitudefrequency relation is interpreted by temporal change of average stress in the focal region on the assumption that the parameter p of the ‘Go game model’ (probability that a fault rupture propagates to the adjacent zone) depends on the stress in the source area.抄録全体を表示PDF形式でダウンロード (1102K) -
―波源の海面変動体積と地震モーメントの関係―羽鳥 徳太郎1984 年 37 巻 1 号 p. 23-29
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーBy applying the Greens's law, the sea-level disturbance at the source area of the Nihonkai-Chubu tsunami (May 26, 1983) is calculated from the coastal inundation heights. By means of the same method, the volumes of the displaced water at the source area, V0, for 18 tsunamis are calculated, where the tsunami source area and the shoaling and refraction factors of the coastal heights are analyzed on the inverse and refraction diagrams, respectively. It is found that V0 is closely related to seismic moment, M0.
1) For the 1983 Nihonkai-Chubu tsunami, the height of the sea-level disturbance averaged over the tsunami source area is estimated to be 123cm, and the peak of 202cm seems to have disturbed in the southern part of the source area. The volume of the displaced water V0 is 12.3×1015cm3.
2) The relation between V0 and tsunami magnitude (Imamura-Iida scale, m) is expressed as
logV0=0.6m+14.7,
where the unit of V0 is ×1015cm3. Combining V0 and the seismic moment M0 (dyne-cm), which is empirically expressed as
logV0=0.78logM0-6.23.
However, the V0 values for the 1896 Sanriku and 1946 Aleutian tsunamis such as “tsunami earthquake” and the Japan Sea tsunamis (the 1940 Shakotan, 1964 Niigata and the present tsunamis) generated by the high angle fault are three times larger then those of the obtained from the above equation.抄録全体を表示PDF形式でダウンロード (579K) -
長谷見 晶子1984 年 37 巻 1 号 p. 31-44
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーFirst arrival time data calculated for an artificial velocity model were inverted using the method based on AKI and LEE (1976) under various conditions. The effect of the number and the quality of data, initial values of source locations and origin times and inhomogeneous source distribution were examined through the results of these numerical experiments. The prominent feature of the results are summarized as follows. (i) Results concerning to peripheral blocks are affected more hardly by the change of conditions than those concerning to interior blocks. (ii) It is difficult to know velocities in blocks ajacent to the outer region even if a large number of stations and sources are used.抄録全体を表示PDF形式でダウンロード (1195K) -
断層ガスの化学的特徴と断層活動杉崎 隆一, 井戸 正彦, 武田 浩, 磯部 由美子, 佐竹 洋, 林 美光, 中村 則明, 水谷 義彦1984 年 37 巻 1 号 p. 45-54
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーGases occurring in fracture zones of active faults were geochemically examined and the relationship between gas quality and fault activity was discussed. Gases charged mainly within fault gouges are characterized by a high cocentration of H2 and CO2. A predominant gas species—H2 or CO2—is related to the lithofacies which the fault cuts. Field observation showed that CO2 tends to occur in sediments and their related rocks, whereas H2 is usually found in igneous rocks and siliceous metamorphic rocks such as gneiss. CO2 concentration systematically varies with temperature and negatively correlated with O2 concentration. This evidence and δ 13C of CO2 (about -20‰) suggests that CO2 is biologically produced from organic materials in sediments. It is likely that, as a results of faulting, circulation of waters and soil airs along fracture zones is pomoted, and biological activity in them increases, giving rise to higher concentration of CO2 in central fracture zone. Carbon dioxide of this kind dose not stem from depths and, accordingly, we cannot expect it to be a useful precursor to earthquakes, although CO2 can be applied to the prospect of a fracture zone buried under sediments. Carbon dioxide with δ 13C of -5‰ to -17‰ in brecciated gneiss containing marble fragments may have been produced by interaction between organically derived CO2 and the marble, or alternatively may have been magmatically derived. If the CO2 is derived from depths, such deep-seated CO2 might be a useful precursor for the earthquake prediction.抄録全体を表示PDF形式でダウンロード (1072K) -
断層ガスの化学的特徴と断層活動杉崎 隆一, 井戸 正彦, 武田 浩, 磯部 由美子, 佐竹 洋, 林 美光, 中村 則明, 水谷 義彦1984 年 37 巻 1 号 p. 55-65
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーHydrogen usually occurs in sheared silicate rocks and its concentration much fluctuates, spatially and temporally. The concentration of H2 from activee faults associated with historical earthquakes usually amounts to as high as several percent in maximum. On the other hand, the H2 concentration from Quaternary faults not associated with historical earthquakes is at most 100ppm. Gases from both types of active faults are impoverished in O2. A series of laboratory experiments showed that (1) hydrogen is produced from a mixture of fresh rock poweder and water and (2) the production rate fluctuates according to rock type, reaction temperature and atmosphere above the mixture. The mixture made of pegmatite powder gave H2 as high as several percent. Oxygen decreased when the reaction proceeded. The experiments suggests that the fresh mineral surface formed by tectonic stresses reacts with groundwater to produce H2. Since the mineral surface loses its activity with time, discrimination between recently moved faults and other Quaternary faults can be made by the H2 concentration. Hydrogen isotope thermomenter, as well as field evidence, suggests a deepseated origin of H2 in an active fault. Successive measurements showed that much H2 simultaneously issued at several monitoring stations on historical active faults and that H2 appeared in bubble gases from mineral springs during about one month prior to earthquakes. The evidence suggests that H2 measurement at monitoring stations gives information at depth on mechanisms that operate perior to earthquakes.抄録全体を表示PDF形式でダウンロード (1118K) -
高橋 学, 木下 重教, 西澤 修, 小出 仁, 千葉 洋1984 年 37 巻 1 号 p. 67-79
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーSeismic wave velocities as well as the three principal strains were measured in the rectangular prisms of Westerly granite (35×35×70mm) under general triaxial compressional state where the three principal stresses are different each others. Measurements were carried out under confining pressure of 50MPa, and under 100MPa and 150MPa intermediate stresses, both with 50MPa minimum principal stress. Compressional velocities for the three principal stress directions and two polarized shear velocities for the minimum principal stress direction were measured during the deformation of specimen.
The P-wave velocity anisotropy between the intermediate and the minimum principal stress direction increased with increment of the intermediate principal stress. The velocity decrease of the two polarized S-waves in the minimum principal stress direction showed considerable difference under confining pressure experiment, while it became almost equal under the higher intermediate principal stress state. Using the relation between velocities and crack densities employed by SOGA et al. (1978), we calculated crack densities and average aspect ratios for the two types of flat spheroidal cracks whose plane are perpendicular to the intermediate and the minimum principal stress directions.
The crack densities for both crack types was equal under confining pressure experiment. On the other hand, the crack density of the plane perpendicular to the intermediate principal stress was reduced remarkably under the intermediate stress conditions resulted from the preferred orientation of cracks with their plane perpendicular to the minimum principal stress. This perferred crack model also explains the equal velocity decrease of the two polarized S-waves under the three different principal stress state. The average aspect ratio of cracks with its plane normal to the intermediate principal stress becomes large under the general triaxial stress state, in comparison with that under confining pressure. This suggests that only thick cracks can survive when the intermediate principal stress acts normal to the crack plane. The calculated average aspect ratios are in line with those determined by HADLEY (1976).抄録全体を表示PDF形式でダウンロード (1232K) -
タベラダム (ドミニカ) の場合寺島 敦, 松本 利松1984 年 37 巻 1 号 p. 81-88
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーIn June and August of 1980 two separate swarms of microearthquakes occurred in the proximity of the Tavera Reservoir, Dominican Republic. The earthquakes were located along the Tavera Fault that runs through Tavera Reservoir. These swarms were observed after abrupt changes of water level occurred. A gradual increase of water level during the period of September through November, however, did dot produce induced earthquakes except sporadic events despite the fact that the highest water level surpassed the peak elevations of two abrupt changes. It was inferred from these observations that the induced seismicity was sensitive to the abrupt changes, especially a rapid draw-down of water level rather than or in addition to the water level itself. The foci of the second swarm in August was distributed adjacent to the area occupied by the first swarm in June, implying that the rock fracture propagated from one zone to another during these two active swarm sequences.抄録全体を表示PDF形式でダウンロード (849K) -
清野 政明1984 年 37 巻 1 号 p. 89-98
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーFor shallow earthquake clusters in and around Japan in 1926-1980 which had main shocks with magnitude M1 of 6.0 or larger, relations among aftershock magnitude, aftershock number and area of aftershock region are statistically investigated. The clusters are classified into three types according to the magnitude sequence as follows: i) the fundamental type in which magnitude gap between the main shock and the largest aftershock exceeds 1.0, ii) the complex type having two or more major events, i. e. the main shock and the aftershocks of which magnitudes are comparable to one of the main shock, and iii) the swarm type.
On the basis of the observed data for the earthquake clusters belonging to the fundamental type, an empirical relation among magnitude M, the number N(M) of aftershocks with M or larger (including the main shock and foreshocks) and the area A (km2) is obtained as follows:
logA=αlogN(M)+βM+γ, (a)
where N(M)≥2, and α, β and γ are constant. Using multiple regression analysis, α and β values are nearly 1, and γ -2.2--2.4. This is transformed into the equation, logN(M)=(1/α)(logA-γ)-(β/α)M, which corresponds to the cumulative frequency-magnitude formula of Gutenberg-Richter's with a constant term dependent on A. When α and β values are approximatedd by 1, the equation (a) is changed into the form, N(M)/A=10-M+2.6. This form means that the clusters have the same apparent density of aftershocks with M or larger in the epicentral regions.
The above relations are also applicable to the earthquake clusters belonging to the complex and swarm types. However, in many cases these clusters have wider epicentral regions compared to one of fundamental type with equal M1. The following model on the formation of epicentral region is statistically examined: the complex or swarm type is consisted of the superposition of two or more fundamental types; the major events in the complex or swarm type individually take part in the formation of the region; the area of the region of complex or swarm type is constructed on the sum of those associated with the events. The results suggest that this model is suitable for the many clusters in the sea region but not always for the inland clusters.抄録全体を表示PDF形式でダウンロード (1005K) -
岡野 健之助, 木村 昌三, 川谷 和夫1984 年 37 巻 1 号 p. 99-108
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーThe 1854 (Ansei) Nankai earthquake is examined on the basis of historical materials, the wave height distribution of tsunami, the hypocenter distribution of recent microearthquakes in Shikoku and its surrounding areas and so on. The aftershock activity is higher in the central part than in the east part of Shikoku, while it is the reverse in the case of the 1946 (Showa) Nankai earthquake. From daily numbers of felt earthquakes in Kochi and Usa which were written in the Kiya Earthquake Diary and the Shinkakuji Earthquake Diary of historical materials, respectively, the difference of aftershock activities between those towns is clearly seen. Although the distance between those towns is only about 15km, felt earthquakes in Usa are two to three times as many as those in Kochi. It may be due to that the aftershocks are less active in Kochi than in Usa and their hypocenters are very shallow. Such phenomena suggest that the focal location of the main shock is located off the Tosa Bay. This inferrence is supported also by the height distribution of tsunami.抄録全体を表示PDF形式でダウンロード (1020K) -
飯尾 能久1984 年 37 巻 1 号 p. 109-118
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーThe mechanism generating the micro-fractures in the mine was investigated.
The micro-fractures occurring immediately after an explosion were observed for about an hour at the Nakatatsu mine in Fukui prefecture in 1982. The depth of the explosion point was about 700m. The velocity of P-wave near the observation site was 6.32km/s. Three accerelation-type seismometers and ten velocity-type seismometers were placed three-dimensionally surrounding the explosion point. The average span between seismometers was about 50m. The accerelation response of the accerelation-type seiemomenter system is flat up to 10kHz and the velocity response of the velocity-type seismometer system is flat up to about 1kHz.
The relative foci to the explosion point were solved from the travel time residuals between the explosion and the micro-fractures. The hypocenters concentrated near one of the corners of the newly excavated face.
The mechanism solution of the micro-fractures is normal-fault type, which indicates that the micro-fractures were generated by the compressional stress in the vertical direction.
The micro-fractures occuring immediately after an explosion are generated by the stress concentration, that the load of the upper mass which had been supported by the rock which was excavated with the explosion concentrates near the corner of the newly excavated face.抄録全体を表示PDF形式でダウンロード (3366K) -
卜部 卓1984 年 37 巻 1 号 p. 119-122
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (1911K) -
小田 仁, 鈴木 功, 瀬谷 清1984 年 37 巻 1 号 p. 122-125
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (1865K) -
本谷 義信1984 年 37 巻 1 号 p. 125-129
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (554K) -
鵜川 元雄, 大竹 政和1984 年 37 巻 1 号 p. 129-133
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (568K) -
音田 功, 吉山 良一1984 年 37 巻 1 号 p. 133-135
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (263K) -
太田 裕, 大橋 ひとみ1984 年 37 巻 1 号 p. 136-138
発行日: 1984/03/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (331K)
- |<
- <
- 1
- >
- >|