Structure-controlled seismic anisotropy along the Karadere–Düzce branch of the North Anatolian Fault revealed by shear-wave splitting tomography

摘要: Abstract We use a three-dimensional (3D) shear-wave splitting (SWS) tomography method developed by Zhang et al. (2007) to map the spatial distribution of crustal anisotropy in Karadere–Duzce branch North Anatolian Fault (NAF) western Turkey. The input data consists 20 751 measurements SWS delay times from 7856 aftershocks 1999 Mw 7.4 Izmit and 7.1 Duzce earthquakes. results show continuous belt-like highly anisotropic zone along Karadere-Duzce NAF, generally ∼ 3 km wide down 5 deep. observed asymmetric pattern Karadere segment is qualitatively consistent with damages unilateral eastward propagation rupture. Another strong region was found near end rupture zone, close dipping direction fault that ruptured during subsequent earthquake. These are shallow fault-zone inferred previous studies. While becomes weaker at depth and/or outside we also identify several regions as deep 10 , primarily within Almacik block. isolated could be explained individual intrusive igneous rock bodies different mineral alignment. Overall, seismic upper crust NAF structurally controlled.