Relation Between Interplate Locking and Microseismicity in the southern Peru subduction

We present preliminary results of the analysis of the interseismic coupling at the southern Peru subduction zone, with special focus on the Nazca Ridge and the Nazca fracture zone. This study is based on the analysis of GPS data from over 120 permanent and field GPS stations collected during the last decade. The obtained GPS velocity field shows the current state of interseismic deformation of the Peruvian subduction margin. The inversion of the geodetic displacements allowed us to estimate the interseismic coupling at the plate interface. Our results show that the interseismic coupling is heterogeneous, with two areas of significant low to weak coupling coefficient, one located over the Nazca ridge and the other in front of the Nazca fracture zone. These results are compared with the spatial distribution of the seismicity recorded by the IGP national seismic network and a temporary seismic network installed as part of the project for the period 2022-2024, which accounts for more than 100,000 events. The analysis reveals a remarkable correlation of the areas where high interseismic coupling is observed with lack of seismicity, whereas in the areas with low interseismic coupling intense seismic activity is observed. These results confirm the hypothesis that the Nazca Ridge acts as a persistent barrier against the propagation of earthquake rupture, and suggest that the interseismic coupling patterns could be associate with the seismic activity. This ongoing work provides valuable information for understanding the tectonic processes in the region and their implications for the earthquake potential.