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2008年汶川地震后,人们不得不思考问题是:大地震是如何发生的?下一次大地震什么时候发生?也就是涉及地质学家和地球物理学家一直未解决的科学问题:断层是如何破裂的?震后断裂是如何愈合的?我们试图通过对汶川地震断裂带结构、断裂摩擦行为和断裂愈合过程的研究来回答这些问题。本文将介绍通过对地表露头和汶川地震断裂科学钻探一号孔(WFSD)岩心中汶川地震主滑移带的详细研究,以及钻孔中长期温度监测来分析有关汶川地震断裂动态弱化和摩擦行为,并结合钻孔中长期水文监测计算所得断裂带渗透率变化,分析震后断裂愈合过程,进而探讨和认识汶川地震断裂作用所涉及的上述问题。经过详细研究,确定了汶川地震断裂带(映秀—北川断裂带)宽105~240 m、具有五个不同断裂岩组合的内部结构,是一条经常发生大地震、具多种弱化机制的断裂带;发现了汶川地震不仅具有同震石墨化作用,而且测量到目前世界上最低的动态摩擦系数(≤0.02),同时首次记录到大地震后断裂快速愈合信息。这些研究结果不仅直接回答了一直困扰在地震地质和地震物理学领域几十年的关键问题,而且对完善地震断裂理论和认识汶川地震机制具有极其重要的意义,为防震减灾提供了理论依据。
After the Wenchuan earthquake in 2008, people had to think about the question: What happened to a major earthquake? When was the next major earthquake? That is, the unsolved scientific questions involving geologists and geophysicists: how faults rupture How Earthquake Fractures Heal? We tried to answer these questions by studying the structure of the fault zone, fracture friction behavior and fracture healing in the Wenchuan earthquake. This article will introduce the detailed study on the main slip zone of the Wenchuan earthquake in surface outcrop and Wenchuan earthquake ruptured hole No. 1 (WFSD) core and the long-term temperature monitoring of the borehole to analyze the dynamic weakening and frictional behavior of the Wenchuan earthquake fault, Combined with the long-term hydrological monitoring drilling drilling fluid permeability calculated changes in the fracture zone, fracture healing analysis after the earthquake process, and then explore and recognize the Wenchuan earthquake fault involved in the above problems. After detailed study, it is confirmed that the Wenchuan earthquake fault zone (Yingxiu - Beichuan fault zone) is 105 ~ 240 m wide and has an internal structure with five different fracture rock assemblages. It is a fault zone with frequent large earthquakes and various weakening mechanisms. It was found that the Wenchuan earthquake not only has the function of coseismic graphitization but also measures the lowest dynamic friction coefficient (≤0.02) in the world at present and records the rapid fracture healing information after a major earthquake for the first time. These findings not only directly answer the key issues that have plagued decades in the field of seismic geology and seismic physics, but also have great significance for improving the theory of earthquake rupture and recognizing the Wenchuan earthquake mechanism and providing a theoretical basis for earthquake disaster prevention and mitigation.