Project Details
Projekt
Deformation mechanisms along the Main Marmara Fault DeMMaF
Subject Area
Palaeontology
Geophysics
Geophysics
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 457268844
The Main Marmara Fault (MMF) in NW Turkey south of Istanbul is a segment of the North Anatolian Fault Zone (NAFZ) that constitutes a right-lateral continental transform fault. Several well-documented strong (M7+) earthquakes indicate that the MMF is a mature active fault with high seismic hazard that poses a great risk to the Istanbul metropolitan region. Along the MMF a 150 km long stretch represents a seismic gap and historical records indicate that the fault is overdue. So far it is unclear whether the seismic gap will rupture in a single large earthquake or several smaller ones and if the next large earthquake would nucleate in the west and propagates towards Istanbul or the other way around. Therefore, the main objective of this proposal is to assess how the rheological configuration of the lithosphere in concert with fluid dynamics influence the present-day deformation along the MMF in the Marmara Sea region. We test the following hypotheses: (1) the seismic gap is related to the mechanical segmentation along the MMF which originates in the rheological configuration of the crust and lithosphere; (2) variations in deformation mechanisms with depth in response to variations in temperature and (fluid) pressure control the mode of seismic activity along the MMF and (3) stress and strain concentrations due to the strength variability can be used as indicator for the nucleation area of the expected strong earthquake. To assess what mechanisms control the deformation along the MMF, we use data collected at the ICDP GONAF observatory (International Continental Drilling Programme – Geophysical Observatory at the North Anatolian Fault) and a combined work flow of data integration and process modelling to derive a quantitative description of the physical state of the MMF and its surrounding crust and upper mantle. Seismic and strain observations from the ICDP-GONAF site are integrated with regional observations on active seismicity, on the present-day deformation field at the surface, on the deep structure (crust and upper mantle) and on the present-day stress and thermal fields. Numerical simulations of coupled thermo-hydraulic-mechanical processes based on the observation-derived 3D models will complement the work flow to evaluate the first order controlling factors for seismic hazard. With an across-scale approach we first develop a regional lithosphere-scale model of the Marmara Sea region as a base to simulate the present-day thermal, stress and deformation fields. This model will be used to extract boundary conditions for two local models that zoom into the areas at the eastern and western tip of the MMF seismic gap representing potential areas for the nucleation point of the next rupture of the MMF. For these local models coupled thermo- hydro-mechanical mechanical simulations will address how the regional configuration interacts with local variations in permeability distribution and fluid motion.
DFG Programme
Infrastructure Priority Programmes
Co-Investigators
Dr. Mauro Cacace; Professor Dr. Oliver Heidbach, Ph.D.
