巻号一覧
55 巻 (2002 - 2003)
- 4 号 p. 337-
- 3 号 p. 249-
- 2 号 p. 91-
- 1 号 p. 1-
前身誌
55 巻, 1 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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田中 明子, 伊藤 久男2002 年 55 巻 1 号 p. 1-10
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーThe thickness of seismogenic crustal layer correlates with surface heat flow in most intraplate seismic areas of the world [e. g., Sibson (1982)]. Although the inverse relationship between heat flow and the base of seismogenic zone is obvious, the quantitative relationships are less certain. One of the reasons is that heat flow measurements are often widely scattered. Another reason is that sparse seismicity of the target area offers little information about the seismogenic zone even though precise hypocentral locations are often available. In this paper, we used the precise focal depth obtained by a microseismic network at the aftershock area of the 1984 Naganoken-Seibu Earthquake with a magnitude of 6.8. In this area, 9 temperature profiles are obtained at boreholes in or near the inferred fault of this earthquake and we determined the heat flow values carefully using these temperature profiles. We also calculated temperatures in the crust using the steady state, one-dimensional, heat conductive transport model with heat generation. The evaluated temperatures at the base of seismogenic zone of this area are about 250°C. This result and previous studies show that the temperatures at the base of seismogenic zone appear to be distributed from about 250°C to 400°C over a large depth interval, 5-30km, at different tectonic settings. It supports that temperature is the dominant factor governing the focal depth. Variations in slip rate, lithology and pore pressure may account for the difference.抄録全体を表示PDF形式でダウンロード (1470K) -
村瀬 圭2002 年 55 巻 1 号 p. 11-18
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーThe author investigated fractal structure of hypocentral distributions before the 2000 Tottoriken Seibu earthquake (MJ=7.3), by estimating temporal changes in the spatial fractal dimension D of the hypocenter distributions, and comparing these results with the seismic activity in and around the focal region. The correlation integral method and the running time-window technique were applied to the D-value calculation for the JMA Earthquake Catalogue data during the period of January 1983 -February 2001. The results obtained are summarized as follows; (1) The D-value decreased drastically prior to the main shock in and around the focal region. The precursory durations are estimated as 1-3 years, which may be different with different sizes of the time-window. (2) The D-value decrease must be caused by hypocenter clusterings, or unusual seismic activity, which occurred over the wide area in and around the focal region. (3) Consequently, temporal variations in the D-values associated with a large earthquake may be effective as a precursor to the earthquake.抄録全体を表示PDF形式でダウンロード (1211K) -
― 0.5～16Hz ―木下 繁夫, 大池 美保2002 年 55 巻 1 号 p. 19-31
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーAttenuation characteristics of S-waves, 1/Q(f), in a sedimentary layer-basement system is measured in a frequency range of 0.5 to 16Hz by means of borehole array recordings at two deep borehole sites, the SHM and IWT sites, in the central Kanto region, Japan. The 1/Q(f) is estimated by matching between the ratio of Fourier amplitude spectrum of surface recordings to deep borehole recordings and the gain of transfer function of a sedimentary layer-basement system for SH-waves. The transfer function is calculated by using the velocity structures at the deep borehole sites and a frequency transformation, frequency transformation which is used to fit the gain of transfer function to the estimated Fourier amplitude ratio. The estimated 1/Q(f) indicates a constant value of about 0.01 in frequencies more than 2Hz. On the contrary, 1/Q(f) decreases with increasing f in a frequency range of 0.5 to 2Hz.抄録全体を表示PDF形式でダウンロード (1456K) -
―中野地区トレンチ調査―三浦 大助, 幡谷 竜太, 阿部 信太郎, 宮腰 勝義, 井上 大榮, 二階堂 学, 橘 徹, 高瀬 信一2002 年 55 巻 1 号 p. 33-45
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーCo-seismic faulting activity during the last three hundred thousands years of the Ichinose fault group, in the southern part of the 150km long Itoigawa-Shizuoka Tectonic Line active fault system, central Japan, was appraised. The Ichinose fault group consists of the mainly two distinct arcuate reverse fault traces bulged toward the east (frontal) and west (behind) directions. We conducted a trench excavation at the Nakano site across the behind fault, where the detailed geological and chronological information for the last ten thousands years was absent. The excavation resulted in evidences for the latest, at least two surface-rupturing events. The events were present sometimes between 665 and 1275 cal.y.B.P. and between 3355 and 4810 cal.y.B.P. The timing of the penultimate event is coincident with the previously estimated latest event on the frontal fault (3, 990-6, 270 cal.y.B.P.). The recurrence time and slip rate between these two events is approximately estimated as 3, 200 years and 0.9-1.8mm/yr in dip-slip, respectively. In comparison with a slip rate estimated from the geomorphological characteristics, the dip-slip rate from our excavation result is coincident well.
A reappraisal of geomorphological reference deposits and a result of the seismic investigation study suggest that the total deformation rate of the Ichinose fault group is 3.5-3.7mm/yr (possibly up to 5.0mm/yr) and it becomes to increase in recent several ten thousands years. While the deformation rate suggests that the co-seismic faulting activity at the Ichinose fault group as a whole is ranked as the one of most active faults in Japan, however, it is smaller than that of 6.3-8.3mm/yr estimated previously from the gravimetric and numerical analyses.抄録全体を表示PDF形式でダウンロード (4576K) -
楠本 成寿2002 年 55 巻 1 号 p. 47-50
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (512K) -
羽鳥 徳太郎2002 年 55 巻 1 号 p. 51-57
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (751K) -
西田 良平2002 年 55 巻 1 号 p. 59
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (178K) -
吉川 大智, 盛川 仁, 赤松 純平, 野口 竜也, 西田 良平2002 年 55 巻 1 号 p. 61-73
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーThe 2000 Tottori-ken Seibu Earthquake brought serious damage to the western area of Tottori prefecture. Anomalous distribution of severe damage of wooden structures was observed in the the Yumigahama Peninsula: that is, the most severely damaged area in the peninsula was located in the most northern part, although it seems that the ground structure of this peninsula is homogeneous from the view of ground surface. To find the cause of such the damage distribution, it is important to understand the ground structure around this area. However, there is little information about the deep structure to the bedrock.
Our objective of this study is to investigate the subsurface structure of Yumigahama Peninsula and to make a two-dimensional detailed model of the bedrock configuration. For this purpose, combined analyses of aftershocks, gravity, and microtremors were carried out on the basis of (1) travel time analysis of after shocks by using ray tracing, (2) Bouguer anomaly from the gravity measurement, (3) spatial auto-correlation (SPAC) method for phase velocity of Rayleigh waves, (4) horizontalto-vertical spectral ratios (H/V) of aftershocks and microtremors. As a result, it was found that the bedrock subsides steeply from the southern part and the depth to bedrock is about 900m in the central part of the peninsula.抄録全体を表示PDF形式でダウンロード (1720K) -
高橋 誠, 小泉 尚嗣, 佐藤 努, 松本 則夫, 伊藤 久男, 桑原 保人, 長 秋雄, 佐藤 隆司2002 年 55 巻 1 号 p. 75-82
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーGeological Survey of Japan made a groundwater observation network composed of 40 stations in and around the Kinki district and Tokai district for earthquake prediction research. In the Kinki district, which is a range of about 34-35.5N and 134.5-136.7E, continuous observation at those wells started in 1998. In the Tokai district, which is in a range of 34.5-35.5N and 137-139E, continuous observation started since 1978. The Western Tottori Earthquake 2000 (M7.3), occurred northwest of the network on Oct. 6, 2000. The epicentral distance to the nearest observation well is about 120km. There was no clear pre-seismic change in groundwater levels on our wells, although co-seismic and/or post-seismic changes were observed at several wells. The analysis of the observational results shows that these had co-seismic step-type changes and/or post-seismic slope-type changes. These co-seismic steps of groundwater level were explained by co-seismic strain changes, but post-seismic slope type changes were not so well. This difference is caused by frequency dependence of groundwater response for strain. Observed co-seismic strain changes were also not so well explained by co-seismic volumetric strain change estimated from the fault model. Our borehole type strain-meters are inferred to detect strain of very local region.抄録全体を表示PDF形式でダウンロード (1139K) -
本多 亮, 平松 良浩, 河野 芳輝2002 年 55 巻 1 号 p. 83-88
発行日: 2002/07/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (5666K)
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