Ambient noise tomography in the Cerro Prieto Basin, Baja California, Mexico from laterally constrained surface wave inversion

Abstract

SUMMARYWe apply a new technique for a laterally constrained surface wave inversion (LCSWI) to estimate the 3-D sedimentary structure of the Cerro Prieto Basin, Baja California, Mexico. The basin contains the Cerro Prieto geothermal field, which is considered one of the most productive in the world. The data used consist of group velocity measurements of Rayleigh waves extracted from cross-correlations of ambient noise registered at 12 stations distributed in an 18 × 12 km area. We estimated an S-wave velocity model that clearly shows three relatively homogeneous geoseismic units that correlate with the stratigraphic column reported in previous studies. The deepest geoseismic unit is the most heterogeneous and shows low-velocity zones likely associated with fluids. The resulting velocity model shows similarity with the conceptual geological model of the geothermal field reported in the literature and recent geophysical studies that suggest the potential existence of another deeper reservoir west of the current exploitation area.