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上世纪70年代以来,国内外基本形成了以监测震中附近断层预滑动进行地震预测的研究思路,但近些年来,一些大地震前近震源区域的形变变化却引起了巨大的争议。本文应用芦山地震震中附近跨断层及连续形变观测资料,分析了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。分析结果表明,沿鲜水河断裂带一些跨断层基线、安宁河及则木河断裂带个别场地的跨断层水准基线出现的显著异常变化,这些异常出现在远离芦山地震震中的区域上;在近震源区域,在龙门山断裂带南段的一些断层水准变化量极小,在鲜水河、龙门山和安宁河3条主要断裂围成的三叉口地区,倾斜、应变、重力及断层水准和蠕变观测临震前未有显著的异常变化,该区是形变变化或形变异常分布的“空区”。本文也与汶川地震前形变异常分布进行了对比,认为震前形变“空区”现象可能是强震前的一种共性特征。
Since the 1970s, the research thought of monitoring the earthquake prediction by the pre-slip fault near the epicenter has been basically formed at home and abroad. However, in recent years, the deformation of near-source regions before some large earthquakes has caused great controversy. In this paper, by using the cross-fault and continuous deformation observation data near the epicenter of Lushan Earthquake, the characteristics of the terrain deformation at different stages before the earthquake are analyzed, and the spatial and temporal evolution of the anomaly in the vicinity of the epicenter is discussed. The results show that there are significant anomalous changes across the fault-level baselines of some cross-fault baselines in the Xianshuihe fault zone, the Anning River and the Zemuhe fault zones, and these anomalies appear on the area away from the epicenter of the Lushan earthquake; In the focal area, some of the fault level changes in the southern segment of the Longmen Shan fault zone are extremely small. The slope, strain, gravity, fault level and creep of the three main fault areas formed by the three main faults of Xianshuihe, Longmenshan and Anning rivers Before observing the earthquake, there is no significant abnormal change, which is the “empty area ” of the deformation or deformation anomaly distribution. This paper also makes a comparison with the anomalous distribution of pre-Wenchuan earthquake. It is concluded that the pre-earthquake deformation “void ” may be a common feature before strong earthquakes.