大震前后地震波列的衰减速率特征

为了从地震记录图中获取大震前后震源物理性质的变化情况，本文给出了新的物理量ＶＦＰ，利用该物理研究了四个大地震前后地震波列的衰减速率变化。结果表明：１９８１年丰镇５．８，１９８４年黄海６．２以及１９８９年大同６．０级大震前的某一时间段内，其地震波列的衰减速率明显增高（表明地震波衰减慢）；大地震发生后期地震波列的衰减速率明显降低（表明地震波衰减快）。１９８３年荷泽５．９级地震前没有直接前震，但是其余震

ATTENUATION RATIO OF TRAIN WAVES BEFORE AND AFTER A GREAT EARTHQUAKE

In order to acquire changes of physicai nature around the focus, this paper has proposed a new physical quantity VFP which was used to study attenuation ratio of train waves before and after 4 great earthquakes. The results show that the attenuation ratio of train waves obviously had increased (i.e.slow wave attenuation) before Fengzhen M=5.8 earthquake in 1981,Yellow Sea M=6.2 in 1984 and Datong M=6.0 in 1989, and decreased after the events (i.e.fast wave attenuation). There was no dirrect foreshocks before Heze M=5.9 in 1983, however, its aftershock train waves had a clear decrease of attenuation ratio.