This paper summarizes the typical features and their regularities of the observed coseismic surface ruptures by Wenchuan Earthquake in terms of the three faults, ground locations, ground geomaterials, rupture geometries and rupture displacements. The paper then uses both the traditional and the author's views to analyze and explain the surface rupture phenomena. The traditional view believes that the earthquake energy was the elastic stress-strain energy accumulated in interlocked stressed hard fault rocks, but leads to unsolvable inconsistency to the observed rupture phenomena. The author's view is based on his discovery of originality that the earthquake energy was the volumetric expansion energy of highly compressed natural gas in deep traps of Longmen Shan fault zone. The author's view leads to the conclusion that the surface rupture phenomena are not complicated and have consistent and systematic regularities with respect to the flash loading of highly pressurized natural gas from the deep fault grounds.
Since the occurrence ofWenchuan Earthuqake onMay 12, 2008, many scientists and researchers went the epicenter areas in northern Longmen Shan and made investigations on the numerous permanent ground damages by the earthquake. One type of the permanent ground damages is the so-called coseismic surface rupture which has a planar rupture surface and some relative displacements of geomaterials on the two sides. The trace of the ruptured surface is continuously and linearly observable on the ground surface along a longitudinal direction and terminates only at the two ends. The coseismic surface ruptures (for short, surface ruptures are used below) are traditionally believed to represent the extension and/or continuation of the dislocation of active sub-surface rock ruptures in deep ground at the ground surface. The active brittle ruptures of sub-surface hard rocks along the deep geological and tectonic faults are traditionally considered responsible for causing the earthquake.
