摘要
在西藏地区分布有一系列近南北向的活动构造带。本区地震绝大部分属于浅源地震。地震活动具有频度高、强度大和复发周期短的特点。地震震中主要分布于活动构造带的边界断裂附近。但在边界断裂转折或交叉部位,震中分布的密度最大,震级较小;而边界断裂的其它部位,一般密度小,震级大。地震断裂带的力学性质主要与其走向有关。北西向为右旋走滑断裂,北东向为左旋走滑性质;近南北向为张性正断层性质。本区控震构造应是活动构造带,发震构造应是活动构造带中的边界断裂。
A series of nearly N-S-trending active tectonic belts are found in Xizang(Tibet).The earthquakes there mostly belong to shallow-focus ones,and are characterized by high frequency,high intensity and short recurrence intervals.The epicentres are mainly located near the boundary faults along the active tectonic belts.They are most concentrated,with small earthquake magnitudes,in the turning or intersecting parts of the boundary faults,and are less concentrated,but with big earthquake magnitudes,in other parts of the boundary faults.The mechanic properties of the seismic fracture belts are generally related to their strike:the NWtrending ones are of dextral strike-slip nature and the NE-trending ones are of sinistral strikesplip nature,while the nearly N-S-trending ones exhibit the nature of tensile normal faults.In the region the earthquake-controlling structures are considered to be the active tectonic belts,while the seismogenetic structures are the boundary faults in the active tectonic belts.
作者
韩同林
Han Tonglin(Institure of Geology,Chinese Academy of Geological Sciences)
出处
《地质学报》
1986年第4期332-338,409,共8页
Acta Geologica Sinica
