Deformation field around a thrust fault: A comparison between laboratory results and GPS observations of the 2008Wenchuan earthquake

摘要

On May 12,2008,an Mw7.9 earthquake occurred in Wenchuan County,Sichuan Province,China.Movement of Yingxiu–Beichuan Fault in the Longmenshan Fault Zone was considered to be the main cause of the earthquake.Earthquakes are closely related to fault activities.Therefore,studying the strain distribution and evolution process around active fault zones is important to the understanding of seismic activities.In this study,we conduct laboratory experiments with uniaxial compression applied to marble sheets with intentionally fabricated cracks.The speckle patterns of the rock samples under different loading conditions are recorded in real time by a digital camera.To calculate the deformation fields of the deliberately cracked marble sheets during different stages of the loading processes,the recorded images are processed by the digital image correlation method.The distribution and variation of the displacement and strain are further analyzed in order to understand the strain localization of and observed damage in the experimental fracture zones.Finally,we compare these laboratory results with the GPS-observed coseismic displacements during the 2008 Wenchuan earthquake,to assess the consistency between our laboratory observations and the field observations of the earthquake,but also to suggest how laboratory results can improve thinking about how earthquake patterns do and do not reflect fault patterns.