Crustal active faults can slip either steadily by aseismic creep, or abruptly by earthquake rupture. Creep can continuously relax the stress and reduce the magnitude of earthquakes. Identifying the slip behavior of active faults plays a crucial role in predicting and preventing earthquake disasters. Here we carried out multiscale structural analyses of fault rocks from the Guanxian‐Anxian fault zone (GAF) surface rupture of the 2008 Mw 7.9 Wenchuan earthquake (Longmen Shan thrust belt, China), and from the 3rd pilot borehole of the Wenchuan earthquake Fault Scientific Drilling project (WFSD‐3P). Results revealed that distributed R1 shears, pressure solution seams, partly dissolved clasts and mineral grains (e.g., quartz and albite), and newly formed phyllosilicate minerals all prevail in the clay‐rich fault rocks at different depths. Microstructural observations combined with X‐ray diffraction analysis show that the majority of clay minerals in the fault gouges were newly formed by pressure solution. The growth of new phyllosilicates prevents soluble grains from coalescing, thereby maintaining fast diffusive paths along solution seams, which promotes the formation of pressure solution. Both weak phyllosilicate minerals and pressure solution can control aseismic creep. Therefore, the slip behavior of the GAF is dominated by long‐term aseismic creep due to the interplay between new phyllosilicate minerals and pressure solution. Based on P wave velocity and strata distribution, we propose a model in which the GAF is creeping at shallow depths and locked at greater depths, as a possible explanation for the Wenchuan earthquake rupture mechanism.

The MS 8.0 Wenchuan earthquake of May 12, 2008, in the Longmen Shan mountain range area in China, led to two roughly parallel NE-trending thrust and strike-slip surface ruptures of the Beichuan, Pengguan, and the Xiaoyudong faults. Coseismic deformation changed the topographical gradient and produced massive landslides and debris flows, causing a corresponding response of the fluvial landforms. In this paper, based on data regarding the surface ruptures and changes to the topography and drainage resulting from the earthquake, the influence of the thrusting and strike-slipping on fluvial landforms and drainage are integrated and analyzed. The results are shown for the following five main aspects: (1) the strike-slipping driven by the earthquake caused the formation of new tectonic diversion points of river channels; (2) the thrusting driven by the earthquake caused the formation of new tectonic slope-break points in the river channel; (3) the strikes of the faults activated by the earthquake controlled the river channel direction; (4) the uplifting driven by the earthquake led to changes of riverbed gradient profiles and their base levels; and (5) exceptionally heavy rainfall after the earthquake initiated landslides, debris flows and floods, and will continue to be a hazard for several decades to come.