论文部分内容阅读
利用震中周围多台地震波资料计算平均波速比， 并对计算误差作了统计和分析， 提出了在介质存在横向不均匀的情况下数据处理方法。在资料有相当可信度的基础上， 动态追踪了１９９６ 年２ 月３ 日云南丽江７ 级地震前滇西北地区波速比的十余年时空演化图象。显示出： 丽江地震孕震区的高波速比异常图象经历了由小到大、由大到小并再次扩大的过程；而低波速比的异常图象则由大到小、由小到大并再次缩小的过程； 地震发生在低波速比异常区包围的高波速比异常区的交汇部位。其时间进程的演化显示丽江地震的孕震区在１９８８年耿马—澜沧７６ 、７２ 级地震后进入非线性阶段， １９９５ 年孟连西中缅边境７３ 级地震前进入失稳阶段。结合滇西北地区地震垂直分布图象和对照含硬包体试样在破裂孕育过程中波速场的演化图象， 表明丽江地震的孕震区具备了坚固体孕震模式的高波速特征
Using the seismic wave data around the epicenter to calculate the average wave velocity ratio, and the calculation error was calculated and analyzed. The data processing method was proposed in the presence of lateral uneven media. Based on the fairly credible data, the temporal and spatial evolution images of more than ten years of wave velocity ratio in northwestern Yunnan before the MS7 Ms3.0 Yunnan earthquake on February 3, 1996 were dynamically tracked. It is shown that the high-speed-ratio anomalous images in the seismogenic zone of Lijiang earthquake have experienced the process of small to large, small to large, and again enlarged. The abnormal images of low-speed-wave ratios have been changed from small to large And then narrowed again. The earthquakes occurred at the intersection of high-speed-ratio anomalous regions surrounded by anomalous regions with low ratios of wave velocities. The evolution of the time course shows that the seismogenic zone of the Lijiang earthquake entered a nonlinear phase after the 1988 Gengma-Lancao earthquake of 7. 6,7 7. In 1995, the seismogenic zone of the Lijiang earthquake entered into the nonlinear stage before the MS7.3 anomaly on the Sino- Unstable phase. Based on the images of vertical distribution of seismicity in northwestern Yunnan and the evolution of the velocity field in the process of rupture of hard-encased samples, it is shown that the seismogenic zone of Lijiang earthquake possesses high-velocity characteristics of strong earthquakes