摘要
Cross-fault permeability measurement was conducted on the Wenchuan earthquake fault. The results showed that this earthquake fault consists of fault core with low permeability (2. 4×10^-19 - 3. 8 × 10^16 m^2 ), highly permeable damaged zone (3.7 × 10^16-3.0× 10-^15 m^2) and the fractured protolith (6.0 × 10^-18 - 4.3 × 10^-13 m^2) (40 MPa effective pressure), among which fresh gouges on the main slip surface are the most impermeable. Impeded by the impermeable protolith and fault gouge, cross-fault fluid flow was inhibited and fluid activity was confined within the damaged zone. This recognition is consistent with microstructure and grain size distribution of fault rocks. Condition of co-seismic thermal pressurization was calculated and the results showed that at depth greater than 2 km, the main slip zone of Wenchuan earthquake has the characteristics of low permeability for thermal pressurization to occur.