Tectonic strain rates in the Anatolia-Caucasus region from Sentinel-I InSAR and GNSS, and their implications for seismic hazard

Geodetic measurements of crustal deformation can provide crucial constraints on a region’s tectonics and seismic hazard. An ideal is for these measurements to be able to directly image deformation well enough (at the surface) that the remaining uncertainty is largely about its depth extent. For this, geodetic measurements need to be five things: spatially dense (on the scale of individual faults), spatially wide-ranging (enough to capture the entirety of strain signals), temporally dense (enough that noise and nuisances can be understood), temporally wide-ranging (enough to bring out gradual interseismic deformation), and accurate. Sentinel-IA InSAR, as processed through large-scale workflows like the COMET-LiCS system and when combined with high-quality GNSS data, is arguably the first geodetic dataset with the potential to be all five. We are using this combination to construct high-resolution maps of crustal deformation and strain across the Alpine-Himalayan Belt. In the Anatolia-Caucasus region, we resolve the large-scale deformation patterns of the North Anatolia and East Anatolian Faults, and a deformation front extending northeastward from their intersection into the Caucasus that is consistent with the locations of large earthquakes. Taking this relationship further, we pair the strain rate map with the Turkish and ISC-GEM seismic catalogues to estimate the recurrence intervals of large, moderate and small earthquakes throughout the Anatolia-Caucasus region assuming conservation of seismic moment. On the North Anatolian Fault, we find that this balance is consistent with the ~250-year recurrence interval between the last two earthquake sequences.