中日震灾科普教育的初步对比分析——地震纪念馆在震灾科普教育方面所起的重要作用

本文通过对比分析,阐述了大地震纪念馆在科普教育方面所起的举足轻重的作用。首先需要加强社会公众地震危机的意识教育,特别是需要从对中小学生关于地震灾害自救意识开始进行培训。同时,就地震专业人士而言,也有责任兼顾科学研究与公众科普教育。相比较日本在这方面的工作与经验,我国需要大力加强这方面的投入,包括人力物力方面的投入。希望本文能对中国防震减灾工作的普及起借鉴和推进作用,使得社会公众更加理性地应对灾害。     

Outline of the fault zone drilling project by NIED in the vicinity of the 1995 Hyogo-ken Nanbu earthquake, Japan

Abstract Three boreholes, 1001 m, 1313 m and 1838 m deep, were drilled by the National Research Institute for Earth Science and Disaster Prevention (NIED) in the vicinity of the epicenter of the 1995 Hyogo-ken Nanbu (Kobe) earthquake to investigate tectonic and material characteristics near and in active faults. Using these boreholes, an integrated study of the in situ stress, heat flow, and material properties of drill cores and crustal resistivity was conducted. In particular, the Nojima–Hirabayashi borehole was drilled to a depth of 1838 m and directly intersected the Nojima Fault, and three possible fault strands were detected at depths of 1140 m, 1313 m and 1800 m. Major results obtained from this study include the following: (i) shear stress around the fault zone is very small, and the orientation of the maximum horizontal compression is perpendicular to the surface trace of faults; (ii) from the results of a heat flow study, the lower cut-off depth of the aftershocks was estimated to be roughly 300°C; (iii) cores were classified into five types of fault rocks, and an asymmetric distribution pattern of these fault rocks in the fracture zones was identified; (iv) country rock is characterized by a very low permeability and high strength; and (v) resistivity structure can be explained by a model of a fault extending to greater depths but with low resistivity.     

Internal structure of the Nojima Fault zone from the Hirabayashi GSJ drill core

Abstract The internal structures of the Nojima Fault, south-west Japan, are examined from mesoscopic observations of continuous core samples from the Hirabayashi Geological Survey of Japan (GSJ) drilling. The drilling penetrated the central part of the Nojima Fault, which ruptured during the 1995 Kobe earthquake (Hyogo-ken Nanbu earthquake) ( M 7.2). It intersected a 0.3 m-thick layer of fault gouge, which is presumed to constitute the fault core (defined as a narrow zone of extremely concentrated deformation) of the Nojima Fault Zone. The rocks obtained from the Hirabayashi GSJ drilling were divided into five types based on the intensities of deformation and alteration: host rock, weakly deformed and altered granodiorite, fault breccia, cataclasite, and fault gouge. Weakly deformed and altered granodiorite is distributed widely in the fault zone. Fault breccia appears mostly just above the fault core. Cataclasite is distributed mainly in a narrow (≈1 m wide) zone in between the fault core and a smaller gouge zone encountered lower down from the drilling. Fault gouge in the fault core is divided into three types based on their color and textures. From their cross-cutting relationships and vein development, the lowest fault gouge in the fault core is judged to be newer than the other two. The fault zone characterized by the deformation and alteration is assumed to be deeper than 426.2 m and its net thickness is > 46.5 m. The fault rocks in the hanging wall (above the fault core) are deformed and altered more intensely than those in the footwall (below the fault core). Furthermore, the intensities of deformation and alteration increase progressively towards the fault core in the hanging wall, but not in the footwall. The difference in the fault rock distribution between the hanging wall and the footwall might be related to the offset of the Nojima Fault and/or the asymmetrical ground motion during earthquakes.     

Estimation of strong motion distribution in the 1995 Kobe earthquake based on building damage data

The 1995 Kobe earthquake caused unprecedented damage to buildings and civil infrastructures in the city of Kobe and its surrounding areas. In order to evaluate the structural damage in this area due to the earthquake, it is important to estimate the distribution of earthquake ground motion. However, since the number of strong ground motion records is not enough in the heavily damaged areas, it is necessary to estimate the distribution using other data sources. In this paper, the fragility curves for low‐rise residential buildings were constructed using the recorded motions and the building damage data from the intensive field survey by the AIJ and CPIJ group. The fragility curves obtained were then employed to estimate the strong motion distribution in the district level for Kobe and the surrounding areas during the earthquake. The results may be useful to investigate the various damages caused by the earthquake. Copyright © 2001 John Wiley & Sons, Ltd.     

Building Damage and Casualties after an Earthquake

The relationship between building damage patterns and human casualties in Nishinomiya City – one of the most heavily damaged cities in the 1995 Hanshin-Awaji Earthquake Disaster – was investigated using photographs of damaged buildings. First, the photographs of buildings in which casualties occurred were identified, and the building damage patterns were judged based on the photographs considering the existence of survival space. Then the relationship between the building damage pattern and casualty occurrence, and the characteristics of casualty distribution, were investigated. The main findings were as follows: Most casualties occurred in relatively old two-story wooden buildings in which the ground floor completely collapsed without survival space; casualties occurred at all building damage levels including ``no damage', and it can be seen that building damage is the major, but not the sole cause, of casualties in an earthquake; in Nishinomiya City, the regional distributions of casualties due to the collapse of buildings that left no survival space is similar to that of casualties due to other types of building damage.     

A Review of “Reconstructing Kobe: The Geography of Crisis and Opportunity”

This paper presents reflections on a research project in women's health, providing both substantive findings surrounding tanning and social status and methodological recommendations for future research. The project under review utilized a picture-elicited storytelling method to: a) understand how women link tanned, bronzed skin to health, status, and attractiveness; and b) test the effectiveness of picture-elicited storytelling as a research method. The project found that, when tanning, women use their bodies to inscribe the social norm of the bronzed aesthetic. While women indicate considerable knowledge of the health dangers of tanning, they continue to link tanned skin to beauty, status, and attractiveness. Further, the research project found that the use of picture-elicited storytelling as a method is potentially powerful but requires considerable attention to concerns of power and representation on the part of the research team.     

Evolution of crustal deformation in the northeast–central Japanese island arc: Insights from fault activity

We evaluated fault activity in northeast–central Japan based on fault orientation, regional stress field, and slip tendency analysis for active and non‐active faults (i.e. faults for which Quaternary activity has not been identified). Slip tendency is generally higher along active faults than non‐active faults, although a high slip tendency was observed along some non‐active faults, indicating their potential to become active. The potential for fault activity along non‐active faults can be modeled using the temporal evolution from non‐active to active during long‐term crustal deformation. The density of potentially active faults varies spatially across the study areas and reflects the temporal evolution of crustal deformation in northeast–central Japan.     

In situ stress measurements in NIED boreholes in and around the fault zone near the 1995 Hyogo-ken Nanbu earthquake, Japan

Abstract The 1995 Hyogo-ken Nanbu (Kobe) earthquake, M 7.2, occurred along the north-east–south-west trending Rokko–Awaji Fault system. Three boreholes of 1001 m, 1313 m and 1838 m deep were drilled in the vicinity of the epicenter of the earthquake. Each borehole is located at characteristic sites in relation to active faults and the aftershock distribution. In particular, the Nojima–Hirabayashi borehole [Hirabayashi National Research Institute for Earth Science and Disaster Prevention (NIED) drilling] in Awaji Island was drilled to a depth of 1838 m, approximately 320 m southeast from the surface rupture of the Nojima Fault, and it crosses fracture zones below a depth of 1140 m. In situ stress measurements by the hydraulic fracturing method were conducted in these boreholes within 1.5 years after the earthquake. Measurement results suggest the following: (i) Differential stress values are very small, approximately 10 MPa at a depth of 1000 m at each site; (ii) the orientation of maximum horizontal compression is almost the same in the boreholes, perpendicular to the surface trace of the faults, north-west–south-east; (iii) fault types estimated from the state of stress differ among these sites; and (iv) the differential stress value just beneath the fault fracture zone decreases abruptly to one-half of that above the fault zone in the Hirabayashi NIED drilling. These features support the idea that the shear stress along the Rokko–Awaji Fault system decreased to a low level just after the earthquake.