论文部分内容阅读
针对巨大地震前经常出现的“环形现象”展开了系统研究，分析了我国及边界地区１６次巨大地震前与部分强震前的环形分布特征，对其普适性、规则性及预测意义进行了讨论．结果表明：巨大地震前数十年至上百年，在其周围经常出现中等以上地震形成的环形分布现象，这个图象具有很强的普适性，不仅无一例外地出现在巨大地震前，而且出现在７级多地震以前．活动环一般出现在巨大地震周围数百公里至上千公里范围（依震级而定）；环内地震活动具有特征不同的三个基本阶段：Ⅰ阶段活动水平较低，分布较散，主震震源区表现为空区；Ⅱ阶段活动性增强，频度、强度、集中度、应变释放率、分布面积率等均增加，空区缩小或消失；Ⅲ阶段活动整体较前期有所减弱，空区再度出现；活动环包围的主震源区在震前数十年可能出现１～３期活动（称为早期、中期与晚期震源活动）；活动环包围的空区长度经历大—小—大的变化过程等．根据活动环出现的区域、长度及环内地震活动状态的分析，可以估计巨大地震的发生地区、震级及地震孕育所处的阶段．这对巨大地震的长期预测是有价值的．本文还对震前活动环的形成机制进行了初步讨论
A systematic study was conducted on the “ring phenomenon” that often occurs before the huge earthquakes. The annular distribution before and after some massive earthquakes in China and its border regions was analyzed. The generality, regularity and forecasting significance discuss. The results show that, before the huge earthquakes for decades to the last century, the ring-shaped distribution of moderate-above earthquakes often occurs around it. This image is very universal and has not only appeared before the huge earthquakes but also appeared Before the earthquake more than 7. The activity ring generally appears in the range of hundreds of kilometers to thousands of kilometers around the huge earthquake (depending on the earthquake magnitude); the seismic activity in the ring has three basic stages with different characteristics: low activity level I and scattered distribution, The activity of Ⅱ phase increased, the frequency, intensity, concentration, strain release rate and distribution area ratio all increased, and the empty area decreased or disappeared. The activity of Ⅲ phase was weaker than that of the previous period, and the empty area reappeared ; The main source area surrounded by the active ring may exhibit 1 ~ 3 activities (called early, middle and late seismic activity) in the decades before the earthquake; the length of the vacant space surrounded by the active ring undergoes the process of big-small-big change . According to the appearance of active rings, the length of the rings and the analysis of the seismic activity in the rings, it is possible to estimate the location of the massive earthquakes, the magnitude of the earthquake and the stage of the earthquake. This long-term prediction of a huge earthquake is valuable. The paper also discussed the formation mechanism of pre-earthquake activity rings