Microzonation of the Linares, Northeast Mexico area, based on geology and shear-wave velocity measurements

We determined the velocity structure of S-wave (VS), P-wave (VP) and the average shear velocity to 30 meters depth (Vs30) at 30 locations in the Linares, Nuevo León area. VS and VP measurements were made from seismic refraction profiles. Four different lithologic units were defined in the upper 30 m: silts with 338 m/s and 221 m/s for VP and VS respectively, which correspond to the lowest velocities measured in the area; Quaternary deposits with 957 m/s and 559 m/s for VP and VS; Tertiary conglomerates with 2471 m/s and 1220 m/s for VP and VS; and shales of the Upper Cretaceous Mendez Formation with 3195 m/s and 2149 m/s for VP and VS. Sites of class C (Vs30 < 760 m/s) are dominant in the area, corresponding to maximum thicknesses of less than 16 m of soft sediments.