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应用芦山MS7.0地震震中附近跨断层及连续形变观测资料,分析了芦山地震前不同阶段地形变变化的特点,讨论了震中附近区域异常时空演化过程.结果表明:①自2013年1月起,沿鲜水河断裂带一些跨断层基线观测到显著的加速转折变化,沿安宁河、则木河断裂带个别场地的跨断层水准基线,2010年以来出现的巨幅异常等是突出的场兆变化;沿龙门山断裂带一些水准观测在汶川MS8.0地震后持续的调整变化具有近震源区变形特征.②鲜水河、龙门山和安宁河3条主要断裂围成的三叉口地区,地倾斜、应变、重力及断层水准和蠕变观测临震前均未有显著的异常变化,GPS水平、垂直位移年速率最小,该地区是形变变化或形变异常分布的“空区”.③在对近场与远场多种连续形变数据通过傅里叶变换提取年周期成分后发现,临震前2—3年近震源区域的地倾斜、重力年变化幅度不是增大,而是减小.芦山MS7.0地震前观测到的形变前兆现象特征与汶川MS8.0地震等震前的前兆现象较为接近.因此,芦山地震前近震源区及外围形变异常分布特征不是个别的现象.
Based on the cross-fault and continuous deformation observation data near the epicenter of the Lushan MS7.0 earthquake, the characteristics of the terrain deformation at different stages before the Lushan earthquake are analyzed, and the spatial and temporal evolution of the anomaly in the vicinity of the epicenter is discussed.The results show that: ① Since January 2013, Significant accelerating and turning changes have been observed along some of the cross-fault baselines along the Xianshuihe fault zone. The cross-fault leveling baseline along the Anning River and Zemuhe fault zones, and the huge anomalies since 2010 are prominent meteorological changes ; Some leveling observations along the Longmenshan fault zone have the characteristics of near-origin deformation after the Wenchuan MS8.0 earthquake.②Tangxikou area surrounded by the three main faults of Xianshuihe, Longmenshan and Anninghe, There were no significant anomalous changes in strain, gravity, fault level and creep observation before the earthquake, and the annual velocity of GPS horizontal and vertical displacement was the smallest, which was the “empty zone” of the deformation or deformation anomaly. After extracting a variety of annual cycle components from a variety of continuous and near-field and far-field continuous deformation data by Fourier transform, it is found that the annual tilt of the near-source region 2-3 years before the earthquake and the annual change of gravity do not increase, Is smaller.The deformation precursors observed before the MS 7.0 Lushan earthquake are similar to the precursors before the Wenchuan Ms8.0 earthquake etc. Therefore, the distribution of the anomalous distribution of the near-source region and the periphery before the Lushan Earthquake is not an isolated phenomenon .