GNSS observations complement dispersion curves of seismic surface waves in southern Patagonia

Abstract

Patagonia is characterized by tectonic and seismic activity, intense geodynamic processes and peculiar mechanical properties of the lithosphere. Surface wave velocity dispersion curves can be derived from seismic records and provide observational constraints to better understand the rheological structure and the geodynamic processes on regional scales, but the seismological infrastructure is sparse in Patagonia. We investigate the potential of GNSS positioning as a complement of seismograms to derive ground particle motion associated to the passage of surface waves of strong earthquakes. Using public 1 Hz GNSS data of permanent networks in southernmost South America and standard GNSS and seismological processing software, we determine 3D coordinate time series interpreted as surface particle motion caused by Rayleigh and Love waves of the Mw 8.8 Maule 2010 and the Mw 8.3 Coquimbo 2015 earthquakes. Group and phase velocity dispersion curves are derived from the GNSS results which are consistent with those obtained from records of collocated seismographs. Our results provide thresholds for the successful application of our approach regarding the earthquake magnitude (Mw>8), the epicentral distance (<5000 km) and the GNSS data rate (≥0.5 Hz). The seismological exploitation of existing GNSS infrastructure can contribute substantially to the determination of mechanical properties of the lithosphere in Patagonia.