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本文对1975年2月4日发生的海城7.3级地震的震前地震活动背景、地震序列和空间分布上的特征进行了研究。 在海城地震的极震区附近,平时很少有地震活动。但自2月1日开始,距震中20公里的营口市石硼峪地震台连续记录到527次前震。这些前震的震中位置很集中,其P波初动符号比饺一致,在时间分布上出现了密集—平静—大震的现象。大震以后的余震很多。 主震极震区的长轴方向与余震分布区的长轴方向和主震震源机制的A节面相一致。由此推测,主震的错动面为北西西走向,可能是高倾角的左旋平移断层的滑动结果。 文中还对临震预报的方法进行了一些讨论。
In this paper, the background of the earthquake before the earthquake of magnitude 7.3 in Haicheng on February 4, 1975, the sequence of earthquake and the characteristics of spatial distribution were studied. Seismological earthquake near the earthquake area, usually very little seismic activity. However, since February 1, 20 km from the epicenter Yingkou Shiubeiyu Seismological Station continuously recorded 527 times the earthquake. The epicenter positions of these foreshocks are very concentrated. Their initial sign of P wave is consistent with that of dumplings, and there is a dense-calm-large earthquake phenomenon in time distribution. Aftershocks after the earthquake are many. The long axis direction of the main shock polar shock zone is consistent with the long axis direction of the aftershock distribution zone and the A section of the main shock focal mechanism. It can be inferred that the mainshock’s misalignment plane is the NWW strike and may be the result of the sloping left-lateral translation fault. The article also made some discussions on the method of prediction of impending earthquake.