地震地表破裂与发震断层的性状

本文在总结地震地面破坏实地考察和统计的基础上,发现地震地面破坏的类型与发震断层的性状关系密切。以走滑为主的发震断层,可产生大规模的地震地表破裂;以倾滑为主的高角度发震断层有时可产生一定规模的地震地表破裂;以倾滑为主的低角度发震断层或连通不好的发震断层,地震地表破裂不发育,而次生的地面破坏普遍发育。倾滑型发震断层产生的地面破坏在多方面具有类似的特征,但逆断层性质的发震断层产生的地面破坏分布在断层下盘,而正断层性质的发震断层产生的地面破坏分布在断层的上盘。并进行了有限元模拟,表明,地震地面破坏分布受断层能量释放区域的控制。

SURFACE RUPTURES AND SEISMOGENIC FAULTS

Usually a mediate and strong earthquake produces a large scale of surface damages.They are divided into two group according to their mechanical nature and distribution. That is, surface ruptures and secondary surface damages. Based on investigation in site and statistics of surface rupture of earthquake; the close relation between surface damages and seismogenic faults are found that is strike slip seismogenic fault may produce a large scale of surface rupturesdip slip one with high pitch, sometimes, could produce an amount of surface ruptures; and dip slip one with low pitch or one on which there are locking regions along a fault, surface ruptures rarely occur, in stead of seriously secondary surface damages on a wide area. Although there is similarity on secondary surface damages which are produccd by dip slip seismogenic fault, ones which are produced by reverse seismogenic fault distribute along down foot of a fault; ones by normal along up foot of a fault. The finite element modeling is made. It is shown that surface damages of an earthquake are controlled by energy releasing region of a fault.