灰岩裸露地区地震勘探野外工作方法的探讨

THE EXPLORATION OF SEISMIC FIELD WORK IN LIMESTONE MOUNTAINOUS REGIONS

在石灰岩裸露地表的山区,从地表到地下,地震波在岩石中传播的速度很高。在高速条件下,为了压制表层干扰波和消除多次波,从理论上讲,可是采用大面积和大排列迭加观测系统。但是,野外施工条件往往限制了大面积组合的应用,而且反射波的视速度由于大排列接收而降低,低速度的波又会受到大基距组合检波的压制。这样就使组合法和迭加法的应用受到一定的限制。在分析了产生这些问题的原因之后,发现若能提高地震波的观测频率,并配合适当的资料处理手段,就有可能改进野外工作方法,提高组合法和迭加法在灰岩裸露地表的山区的应用效果。

In limestone mountainous regions, the velocities of seismic waves are almost always in extraordinary high values. In order to suppress the surface waves and eliminate the multiple reflections, the big-area-geophone-array and the long coverage spread of detectors could be adopted theoritically. But the application of such geophone array is constantly restricted by the working conditions in the field, the apparent velocity will be lessened by the long spread and the waves in low appa- rent velocity are suppressed by the long base length geophone array. Therefore, the application of geophone array and multiple coverage will, to some extent, be restricted. After analysing the causes of the appearance of the phenomena mentioned above, we found that if the frequency of seismic wave observed could be expected to be higher and some proper processing measures could be taken, it would be possible to improve the effects of geophone array and multiple coverage in the limestone mountainous regions.