Seismic site effects in the central zone of Monterrey Metropolitan Area (northeast Mexico) from a geotechnical multidisciplinary assessment

Prediction of the ground shaking response requires data expressed in terms of soil dynamic properties. Based on the analysis of surficial geology, geotechnical borehole data, seismic refraction (VS) and microtremors (H/V) surveys, we have developed a qualitative evaluation of local ground response to earthquakes in the Monterrey Metropolitan Area (MMA), the main urban and economic hub in northern Mexico. The results provide a detailed geotechnical model for the central zone of the MMA. Although such information is not yet complete for the MMA region, an initial approach has been developed in order to estimate the distribution of damage associated with expected moderate earthquakes. An empirical correlation is introduced to obtain VS as a function of standard penetration test blow counts (SPTN). According to the results, the central-southern part of the study area might experience higher amplifications of ground shaking produced by moderate seismicity because the larger thicknesses of alluvial sediments are deposited there. The 2D geotechnical model proposed would be very useful in making decisions regarding planning or land use, deployment of protocols of rapid response and for producing detailed microzonation maps for those zones with similar geological features as the MMA in northeast Mexico.