Crustal deformation in the south-central Andes backarc terranes as viewed from regional broad-band seismic waveform modelling

SUMMARY The convergence between the Nazca and South America tectonic plates generates a seismically active backarc region near 31 ◦ S. Earthquake locations define the subhorizontal subducted oceanic Nazca plate at depths of 90‐120 km. Another seismic region is located within the continental upper plate with events at depths 1.80, th = 45‐55 km) than those of the eastern Sierras Pampeanas (Vp = 6.0‐6.2 km s −1 , Vp/Vs < 1.70, th = 27‐35 km). In addition, we observed an apparent distribution of reverse crustal earthquakes along the suture that connects those terranes. Finally, we estimated average P and T axes over the CHARGE period. The entire region showed P- and T-axis orientations of 275 ◦ and 90 ◦ , plunging 6 ◦ and 84 ◦ , respectively.