康定6.3级地震前鲜水河南段跨断层形变异常分析

2014年11月22日,四川省甘孜州康定县（30.3°N,101.7°E）发生6.3级地震,震源深度18km。地震发生在有跨断层形变测量场地的鲜水河断裂带康定至道孚之间的色拉哈断裂。结合该断裂带2000年以来的跨断层形变观测资料,笔者重点对老乾宁、折多塘监测场地在康定地震前的观测资料进行了分析,得出了以下结论：①从2013年5月开始,老乾宁基线观测曲线持续上升,反映出鲜水河南段断层张性活动有所增强;②老乾宁、折多塘场地短水准观测曲线2014年5月至9月加速下降,断层压性活动增强,有明显的短期异常;③老乾宁、折多塘短水准异常对康定6.3级地震的短期预测有着明确的指示意义。

Analysis of Cross-Fault Deformation Anomaly before MS6.3 Kangding Earthquake in Southern Segment of the Xianshuihe Fault

On November 22, 2014, MS6.3 earthquake with the focal depth of 18km took place in Kangding County, Ganzi Prefecture in Sichuan Province (30.3°N,101.7°E). The earthquake occurred in the Selaha segment of Xianshuihe fault zone between Kangding and Daofu where cross-fault deformation monitoring has been undertaken. Combined with the monitoring data since 2000, we analyzed the data especially for that from Laoqianning and Zheduotang fields before the earthquake. The results show that: (1) Since May 2013, Laoqianning baseline observation curve has kept upward, which reflected that tensile activities of the southern region of Xianshuihe fault have enhanced. (2) The observation data of Laoqianning and Zheduotang short leveling shown that the curve trend declined rapidly from May to September 2014, which is a short-term anomaly and indicates that the compressive movement of the fault have enhanced. (3) In conclusion, these above anomalies of Laoqianning and Zheduotang short leveling may have some significance in short-term prediction for Kangding earthquake.