Study on Concealed Active Fault in the Urban Area of Kobe

研究了1995年神户大地震(M&lt；JMA&GT；7.2)同震地面破坏与神户市区隐伏活动断裂的关系。1307根倾斜的电线杆和1,277个错位的房屋入口处估计了地面损坏。我们使用200 MHz和100 MHz天线的探地雷达(GPR)方法对地震反射调查(兵库县政府、关西地区地震观测与研究委员会等)发现的隐伏活动断裂进行了详细检查。结果表明：(1)神户市区强震害有一定的特点，呈点状和线状分布。其线性展布与罗科山著名的Goshkebashi断裂向西南延伸相一致。(2)晚更新世至全新世地层在10m宽的地表以下存在两个变形带，一个位于隐伏断层(Oji断层)上方，另一个位于神户市石谷川河公园下方的Mikage挠曲带上。它们分别从Gosukebashi断裂和Mikage挠曲向西南伸展。(3)探地雷达剖面上的两个变形带与严重受损的生命线(电线杆、房屋入口等)相协调。在地震期间。

We investigated , the relationship between the co-seismic ground damages during the 1995 Hyogoken-Nanbu Earthquake (M_<JMA> 7.2) and the concealed active faults in the urban area of Kobe. The ground damages were estimated from 1307 inclined utility poles and 1,277 dislocated house inlets. We used the ground-penetrating radar (GPR) method with the 200 MHz and 100 MHz antennas for the detailed examination of the concealed active faults, which were found by seismic reflection surveys (Hyogo Prefecture Government, Committee on Earthquake Observation and Research in Kansai Area, etc.). The following results were obtained in the urban area of Kobe : (1) The strong ground damages have the characteristic pattern, distributing as spots and lines. The linear distribution is consistent with w southwestward extension of the well-known Goshukebashi fault in the Rokko Mountains. (2) the two zones of deformation in the Late Pleistocene to Holocene strata such as discontinuity and flexure were found in a subsurface zone of 10 m wide : One is located just over the concealed fault (Oji fault), and the other is at the Mikage flexure beneath the Ishiyagawa River Park, Kobe City. They appeared respectively to the southwestward extension from the Gosukebashi fault and the Mikage flexure. (3) The two deformation zones on the GPR profiles, are in harmony with the strongly-damaged lines of lifelines (utility poles, house inlets etc.) during the earthquake.