In this contribution, we discuss our latest results from the project “Deformation Mechanisms along the Main Marmara Fault (DEMMAF)”, funded by the ICDP priority program of the German Science Foundation. The Main Marmara Fault (MMF), is the northern branch of the North Anatolian Fault along the Marmara Sea (NW Turkey). The MMF has produced several major earthquakes (M7+) in the past with a recurrence of about 250 years, and has not ruptured since 1766. The goal of the DEMMAF project is to investigate what controls the deformation mechanisms along the MMF, using data collected at the ICDP GONAF observatory (Geophysical Observatory at the North Anatolian Fault) and a combined work flow of data integration and process modelling approach.
Here, we use a forward numerical approach that implements frictional faults and visco-elastic off-fault materials to investigate the space- and time-scales of the long-term seismic behavior of the Main Marmara Faults and its main controlling factors. The MMF is modelled following a Coulomb frictional constitutive law and the spatially variable off-fault rock properties are derived from a data-integrative lithospheric-scale 3D structural model of the region around the MMF. The forward model is used to test the effect of varying boundary conditions (i.e. kinematic) and fault strength properties (i.e. coefficient of friction). Our modelling approach highlights the first order role of crustal rheology and fault-strength in the long-term behavior of the MMF (spatial distribution and recurrence of seismic events), as well as their potential to explain the along fault locking degree variability.