分别采用阈值法、速率变化法、趋势转折法和破年变法4种方法,对昭通地区全部地下流体观测资料进行预报效能R值定量计算。针对预报效能较好的测项,依据异常特征和水化学特征,并结合已有研究成果,对这些异常产生的孕震机理进行讨论。结果表明,昭通地区大多数流体异常的最佳预测时段在3个月以内,尤其是速率类异常和趋势转折类异常在出现转折后,具有较好的短临预测意义; 11个测项的预报效能R>R₀,可作为滇东北地区日常跟踪的重点测项; 推断认为大多数异常属于大气降水产生的流体力作用诱发的浅层前兆异常。

Four methods,including threshold method,rate change method,trend transition method and annual change method,were used to quantitatively calculate R value of forecasting efficiency of all same underground fluid data in Zhaotong area. Based on the characteristics of anomalies and water chemistry,the seismogenic mechanism of these anomalies was discussed. The results showed that the best forecasting period of most fluid anomalies in Zhaotong area was within 3 months,especially after the anomalies extracted by the rate method and the trend turn,which is relatively significant for forecasting in short to imminent stage. The forecasting efficiency R>R₀ of 11 test items can be used as key test items for daily tracking anomaly in northeast Yunnan. It was concluded that most such the shallow precursor anomalies were caused by fluid force induced by atmospheric precipitation.

P315

中国地震局星火计划项目“滇南—滇西南地区地下流体异常深浅耦合关系研究”(XH21030Y)资助