The Wenchuan earthquake of the 12th of May 2008, in Sichuan County, China can be classified as a large-scale event based on the tectonic structures that triggered the earthquake and the effects caused on the human, structural and natural environment. This paper presents the geotectonic and seismotectonic regime of the earthquake affected region on the basis of field data obtained along the seismic fault zone and provides: (i) an estimation of the intensity values according to the EMS1998 and the ESI2007 scales and the determination of their large-scale geographical distribution along the causative tectonic structure, (ii) an interpretation of the intensity distribution according to the seismotectonic, geodynamic and geotechnical framework, and (iii) a comparison between two different intensity scales, the EMS1998 which is essentially based on the effects on the built environment and the ESI2007 which is based on Earthquake Environmental Effects (EEE). The application of both EMS1998 and ESI2007 and the comparative review and evaluation of the results indicate that the estimated values of the EMS1998 and the ESI2007 were similar. This suggests that both scales can be useful and reliable tools for seismic hazard estimation.