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１９９５年７月１２日至１９９６年２月３日短短７个月，云南地区连续发生了孟连西中缅边境７．３级、武定５．５级、丽江７．０级３次强震，本文研究了近期这几次强震前５个地震台地震图垂直分量Ｓ、Ｐ波最大振幅比的时空演化特征，动态追踪了振幅比明显偏离平稳态的突变过程。发现主震前５—８年，７级大震震中１００ｋｍ范围出现振幅比高（低）值突变，６级强震震中１３０ｋｍ范围出现振幅比高值突变，当振幅比的突变在缓升（降）的背景上骤升（降），或突变异常的地震次数明显增加，则中长期异常进入中短期阶段。在强震震中１３０ｋｍ范围内的地震台（近台）振幅比值高达１５．２以上，而远离强震震中２５０ｋｍ以外的地震台（远台）振幅比最大值仅为９．８，近台的突变幅度至少比远台大３０％。而强震成组发生前一年半时间内，位于强震震中１１０ｋｍ范围内的近台振幅比的突变幅度比远在２５０ｋｍ外远台大５５—７５％。对振幅比的突变和时空演化特征从非线性动力学模型和模拟实验结果进行了初步成因探讨。
From July 12, 1995 to February 3, 1996, in the short span of seven months, the Menglian West border between China and Myanmar continued to rank 7.3, Wuding 5.5, Lijiang 7.0 at the third level In this paper, we study the temporal and spatial evolution characteristics of the maximum amplitude ratio of S and P waves of the seismograms of the seismograms in recent seismographies in the recent several times, and dynamically track the abrupt change of the amplitude ratio significantly away from the steady state. It is found that there is a sudden change of amplitude ratio (low value) in the range of 100 km before the main earthquake and in the range of 130 km in the epicenter of the MS7 magnitude earthquake. When the amplitude ratio is abruptly increased ), Or the number of earthquakes with abnormity increases obviously, then the long-term anomalies enter the short-to-medium term. The amplitude ratio of seismic stations (near stations) within 130km of strong earthquakes was as high as 15.2, while the maximum amplitude ratio of seismic stations (far stations) 250km away from the epicenter of strong earthquakes was only 9.8. At least 30% more than the far stage. Within a year and a half before the occurrence of strong earthquakes, the magnitude of the sudden change in amplitudes of nearby stations located within 110km of a strong earthquake epicenter was 55-75% larger than that of a distant station 250km away. The initial genesis of the abrupt change of the amplitude ratio and the characteristics of space-time evolution are discussed from the nonlinear dynamic model and simulation results.