江苏及邻区中强震前的非线性失稳特征及地震趋势分析

NONLINEARITY INSTABILITY CHARACTERISTICS AND SEISMIC TREND ANALYSIS BEFORE MODERATE EARTHQUAKES OF JIANGSU AND ADJACENT AREA

加卸载响应比是一个表征非线性系统失稳程度的量，在国内外的地震预报中已有广泛的应用。本文选用江苏及邻区（Ｎ３０°００′～３６°００′，Ｅ１１７°００′～１２３°３０′）１９７００１～１９９８０９的地震资料，研究了该区域内５级以上地震（共１２个）前的加卸载响应比变化的特点，并对未来的地震趋势作了估计。研究结果表明：１２个震例中有１１个震前有明显的响应比异常；异常的平均持续时间为８．５个月；异常的最大值绝大多数在１０之内；异常最大值出现时间至发震时间多数是在１～２．５年之间。研究结果对今后在预报工作中认清该地区非线性失稳的特点，提高预报效率有重要的参考价值。

The characters of load and deload response ratio before 12 M S≥5.0 earthquakes of Jiangsu and adjacent area (N 30°00′～36°00′,E 117°00′～123°30′) have been researched using the earthquake data of this region from January 1970 to september 1998, and earthquake tendency has been estimated. It is concluded that there are obvious response ratio anomalies in 11 of 12 earthquake cases, the average duration time of anomalies is 8 months, the maximum values of anomalies are almost less than 10, there are most 1～2.5 years from the moment of the maximum value to one of earthquake occurrence.