Earthquake cycle of the North Anatolian Fault along the rupture zone of the August 17, 1668 Great Anatolian Earthquake

Abstract

We investigated the earthquake cycle along the 450-km rupture zone of the August 17, 1668 Great Anatolian Earthquake (M8.1) combining GPS and earthquake data. We elaborated on elastic rebound theory investigating creeping and locked stages of the individual fault segments. We simultaneously estimated segment-based slip rates and locking depths. Slip rates are used to estimate preliminary inter-seismic slip stor ages assuming fully locked fault segments right after the mainshocks. Misfits between co-seismic slips and preliminary inter-seismic slip storages indicate that the fault does not store slip for a while after major earthquakes. Our analysis shows a partitioning between creeping and locked stages. Only along one segment, the 1943 M7.7 rupture, creep played a minor role during the seismic cycle (0.1%). Along the 1939 M7.9, 1957 M7.0, 1967 M7.2, and 1999 M7.5 ruptures, creep played a considerable role (16.9%, 22.2%, 17.9% and 22.4%, respectively). Along the 1942 M7.1, 1944 M7.4, 1999 M7.1 rupture zones, creep played a substantial role, and covered almost half of the seismic cycle (54.4%, 44.0% and 48.3%, respectively). The segments host currently differ ent earthquake potentials as they have distinctive creeping/locking rates despite the fact that they are exposed to similar deformation rates (between 19.5±0.5 – 24.2±0.3 mm/y). Our results show that slip rates systematically accelerate from the east to the west. Failure of the NAFZ will probably end at the western segments within 239±3 years. The space-time pattern of the earthquakes during the last three complete and the current incomplete cycles confirms that the failure of the NAFZ starts from the east, and systematically migrate to the west deceleratingly.