断块构造、活动断块构造与地震活动

Fault-block tectonics, active fault-block tectonics and earthquake activity

张文佑院士是我国最杰出的构造地质学家和大地构造学家,他提出和倡导的地质构造力学分析和历史分析相结合及断块构造理论符合当代构造地质和构造运动研究的新方向。断块构造是地球构造运动最基本的型式,板块构造是全球范围内的岩石圈构造,是最高一级的岩石圈断块构造。活动断块是现今构造运动最基本的型式,它既控制主要活动构造带和地震活动带的分布,也控制不同地区地震活动特征的差异。断块边界构造带是在构造变形和运动场中的不连续变形带,应力在此释放,应变在此局部化,位移在此发生,其差异活动最为强烈,因此,断块边界构造带是强震发生带,其活动性质会控制震源断层的特性。大地震孕育和发生在边界活动构造带的某些特殊部位,对其成核的构造和物理过程尚需深入进行研究。要特别注意断块整体性活动对地震活动的控制作用,断块的这种整体性活动与一定时期内地震活动主体地区分布有密切关系,所以,在活动构造研究中,要把断块的整体性活动与活动构造带的个体活动结合起来。

Professor Zhang Wenyou, one of the few most outstanding Chinese geologists in structural geology and tectonics ,proposed and facilitated fault-block tectonics theory which emphasizes the combination of mechanical and historical analysis of geological structures. The idea and theory of fault-block tectonics still coincide with present-day directions of worldwide tectonic studies. The fault-block tectonics appears to be the basic kinematic type of global lithospheric movements. Lithospheric plates are global scale tectonic units that may be viewed as the highest rank of fault-block. Active fault-block movements are the basic style of present-day deformation, which not only controls distribution of active tectonic zones and earthquake belts, but also impacts regional pattern of earthquake activity. Boundaries of active fault-blocks act as discontinuous zones with the most intense differential movements during the processes of active tectonic deformation. Strain localizes, accumulates and finally releases along the boundaries to cause great earthquakes. Thus ,the fault-block boundaries are in fact the strong earthquake belts, and their styles of deformation dictate the types of earthquakes. Great earthquakes occur on some specific positions of fault-block boundaries, their nucleation tectonics and physical processes however have not been understand yet and deserve comprehensive studies. Special attention should also be paid to the controlling effects of entire fault-block movement to regional seismicity. The entire motion of a fault-block in a special time span may control or strongly influence the pattern of seismic activity in a specific region. It is needed to combine the entire fault-block movement and tectonic activity of a specific fault-block boundary to understand the causal mechanism of a seismic belt during active tectonic studies on either a region or an individual belt.