象力在震源过程和地震短临预报中的作用

APPLICATION OF THE IMAGE FORCE TO EARTHQUAKE SOURCE PROCESS AND TO SHORT-TERM AND IMMEDIATE PREDICTION OF EARTHQUAKE

摘要:

在固体物理学中,象力是指自由面吸引裂缝的力量,本文把这一概念用于不均匀地壳中,则象力可定义为地壳中任何易于变形,让位界面对裂缝的吸引力。按照这一观点,我们讨论了象力在组合模式和短临预报中的作用并得到如下结论。
1.组合模式中的应力调整单元,如蠕滑断层,塑性区,裂丛区等可以近似为自由面。因而它对于积累单元预位移的传播或裂缝的传播具有吸引力。
2.象力出现的标志是当传播的预位移和裂缝端部产生的动态应力场达及调整单元时,此时调整单元发生形变监产生前兆。当裂缝由深处向浅处传播,其端部的动态应力场达及自由面时,此时自由面用形变来满足自由面条件从而引起前兆。
本文的讨论表明,震源两端的调整单元的同时性表明大震的发生为期不远了。因此调整单元对于预位移和裂缝的传播具有监视作用。本文以海城地震前兆特征为例讨论了这个问题。并由此认为组合模式中调整单元的象力作用比单向蠕裂断层面向震源区的传播更符合实际情况。

Abstract:

In solid physics, the image force is a force with which the free surface attracts the crack to wards itself. In reality the earth surface is a typical free surface. Besides, we regards the adjustmentary elements in combination model of source preparation, such as creep fault, plastic region, cracks region and the like, as free surfaces to some extent. According to the above-mentioned view point, we discuss some questions as follows:
1. When the creep slip just before earthquake in stress accumulation element is propagating and near to the free surface, and the free surface Will attract the creep slipping to wards itself.
2. When one of adjustmentary elements located at the end of earthguake source begins to extend, other adjustmentary elements will attract it promote its propagation.
3. When the appearance of some short-term and immediate precursors on the earth surface or adjustmentary elements is synchronized with the image force,it means that the-image force has already influenced the source and the earthguake will soon occur possibly.