Different modes of stress transfer in a strike-slip fault zone: an example from the North Anatolian Fault System in Turkey

Abstract

The dextral North Anatolian Fault System (NAFS) extends for well over 1000 km from the compressive tectonic domain of eastern Anatolia into the broad and diverse tectonic domain of the western Anatolian, Marmara and Aegean regions. These different tectonic regimes are characterized by a narrow deformation zone in the east and a much broader deformation zone with multiple sub-parallel fault zones in the west. The spatial and temporal distribution of large historical and modern earthquakes (Mw>5) shows two distinctive macro-seismic zones in the eastern and western parts of the NAFS. The eastern macro-seismic zone, between the towns of Erzincan and Bolu, has produced a successive linear earthquake series parallel to the fault system over the last 500 years, suggesting that stress transfer along the fault occurred in a manner of 'Static Coulomb failure stress changes' through the entire elastic crust. In contrast, the western macro-seismic zone of the NAFS, in the Marmara region, has produced successive earthquake pairs on the parallel faults, implying 'dynamic stress changes', involving large-scale flow in the aseismic lower crust and the mantle.