权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Research on earthquakes, crustal movements and groundwater discharge changes in the Rokko active fault region

六甲活动断裂带地震、地壳运动及地下水流量变化研究

基本信息

批准号：
08454123
负责人：
FUJIMORI Kunio
金额：
$ 1.86万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

Continuous observations of crustal strains and tilts have been executed in the stations (Rokko-Takao, Rokko-Syakunage and Rokko-Turukabuto), which are located within the focal region of the 1995 Hyogo-ken Nanbu earthquake (M=7.2). The observation tunnels of the Rokko-Takao and Rokko-Tsurukabuto are crossing with the Manpukuji and Otsuki faults, respectively. In the Rokko-Takao, change in groundwater discharge from the fracture zone of the Manpukuji fault has beeu also measured. In this work, the observations were continued after the earthquake, and the data analysis was done.At the Rokko-Tsurukabuto station, a maximum strain change of 400μ strain and a maximum height change of 8.7mm caused by the earthquake were observed. Short-term changes or changes immediately before the earthquake were not detected, but a slow decrease of strain rates, small rotations of the maximum strain directions and a relative upheaval of about 0.1mm/year continued for a long time prior to the earthquake. After the earthquake, the Otsuki fault started lateral and vertical dislocations of a rate of 0.1-0.2mm/year. The dislocations are the same sense as the Quaternary movements of the fault.A post-seismic crustal deformation which has a comparatively long time constant might be observed after a step-like coseismic crustal deformation. As causes where such deformatian is caused, an after-slip in the vicinity of a hypocenter, and a visco-elastic response of the crust to coseismic slipping have been considered. In present research, we consider that the coseismic strain changes generate the coseismic pore pressure changes which corresponds to the strain changes and that the postseismic crustal deformation is caused by groundwater migrations from the high pressure areas to the low pressure areas including the ground surface. The migration rates might be controlled by permeability of those areas.

在1995年兵库县南部地震（M=7.2）震源区内的台站（Rokko-Takao、Rokko-Syakunage和Rokko-Turukabuto）进行了地壳应变和倾斜的连续观测。六光-高尾和六光-鹤武登的观测隧道分别穿过万福寺和大月断层。在六古-高尾，还测量了从万福寺断层断裂带流出的地下水流量的变化。本工作在地震发生后继续进行了观测，并进行了数据分析，在六光鹤釜站观测到地震引起的最大应变变化为400μ应变，最大高度变化为8.7mm。短期变化或临震前变化未被检测到，但应变率缓慢下降，最大应变方向的小旋转和约0.1毫米/年的相对隆起在地震前持续了很长一段时间。地震后，大月断层开始以每年0.1- 0.2毫米的速率发生横向和垂直位错。断层错动与第四纪运动意义相同，在一次台阶状同震地壳形变之后，可能出现一次时间常数较长的震后地壳形变。作为引起这种变形的原因，震源附近的后滑动和地壳对同震滑动的粘弹性响应已被考虑。本文认为，同震应变变化引起了与应变变化相对应的同震孔隙压力变化，震后地壳形变是由地下水从高压区向包括地表在内的低压区运移引起的。运移速率可能受这些区域的渗透率控制。