摘要
本文研究了荷泽5.9级地震前小震波速比时空变化特征,发现在荷泽附近大约2°×2°范围内出现了持续两年的小震波速比低值异常集中分布区,当集中区内波速比回升到极大值后小震活动平静,然后波速比低值区向外围扩散,当外围出现波速比极小值且逐渐回升后,在低值集中区内主震发生。震前小震波速比低值异常持续三年,直到主震前半个月波速比恢复正常。最后本文对波速比异常的有关问题进行了讨论。
In this paper, the temporal-spatial variation characteristics of wave velocity ratios of small earthquakes before the Heze earthquake with Ms 5.9 are studied. It is found that there is a concentrative area of low value anomaly of wave velocity ratios near Heze for two years. When the wave velocity ratio rises again up to the maximum value in the concentrative area, the activity of small earthquakes becomes quiet. Then the low values of wave velocity ratios extend toward outer. When the wave velocity ratios of small earthquakes in the periphery change to the minimum value, and then the values rise again to normal, the mainshock occurred in the concentrative area of low values. Before the mainshock, the low values of wave velocity ratios last three years, restoring to the normal values until about 15 days prior to the mainshock. Finally, some relative problems about the wave velocity ratio anomaly are discussed.
出处
《西北地震学报》
CSCD
1991年第1期30-34,共5页
Northwestern Seismological Journal