Probing the mechanism of slow slip events along the central North Anatolian Fault Zone

Along the central section of North Anatolian Fault Zone, which marks the boundary between the Eurasian and Anatolian plates, subsurface creep has been detected since the 1970s. This creep localizes within a ~60-70 km-long segment along-strike, known as the Ismetpasa segment. Measurements from creepmeters, GNSS and InSAR, show that aseismic slip occurs as episodic events, or slow slip events (SSEs), that last a few weeks, occur approx. every 2.5 years, and extend to a depth of 5 – 6 km. Notably, the location of these SSEs coincides with a region of shallow locking depth.  Several mechanisms have proposed to explain their occurrence, including elevated pore-fluid pressure, variation in fault-zone composition, and changes in stressing rates associated with the shallower locking depth. To understand the mechanisms that govern these events, we carry out 3D numerical simulations using rate and state friction. In our model, we explore the effect of effective normal stress, long-term slip rate distribution and friction parameters on the resulting slip behavior. We consider a range of model setups and identify scenarios that reproduce the first-order characteristics of Ismetpasa SSEs. Our results provide insights into the conditions that promote shallow and deep slow-slip on continental strike-slip faults.