Multi-objective inversion of surface waves and receiver functions by competent genetic algorithm applied to the crustal structure of the Parana Basin, SE Brazil

Surface wave dispersion and receiver functions are sensitive to different, but dependent, seismic properties. Their joint inversion is multi-objective and can provide tight constraints on layer-interfaces and S-velocities. We used one of the competent genetic algorithms, Bayesian optimization algorithm, as the multi-objective inversion technique. Multi-objective criterion of receiver functions and surface wave dispersion can better constrain solutions than each separate objective. We applied this new method to data from three stations in the Parana Basin, Brazil, and found S-velocity structure well-constrained down to 150 km depth. The inverted S-velocities in the lower crust are less than 3.8 km/s and are lower than in the surrounding foldbelts. Some indication of high velocities (Vs > 4 km/s) in the 5-7 km lowermost crust is given by a Moho transition zone. This may suggest that possible underplating was not widespread in the Parana basin.