Near-fault Strain Rates Along Western North Anatolian Fault by GPS

Monday, 15 December 2014
Asli Dogru, Haluk Ozener, Bahadir Aktug, Semih Ergintav, Bulent Turgut, Onur Yilmaz, Kerem Halicioglu and Asli Sabuncu, Bogazici University, Kandilli Observatory and ERI.-Department of Geodesy, Istanbul, Turkey
We have been observing periodically three small-aperture geodetic networks established the main strands of the western North Anatolian Fault (NAF) by GPS since 1994 and two others since 2005. The main objective of this research is to monitor the partitioning of the strain along the active splays of NAF. The occurrences of 1999 earthquakes also enabled to quantify co-seismic and post-seismic deformation in addition to the inter-seismic deformation. Furthermore, current network scheme allows to monitor the recently discovered aseismic creep along rupture of Izmit earthquake, which require near fault observations. Periodic observations at these micro-geodetic networks enable us to clarify how accumulated strain is distributed across spatial and temporal scales. In this study, we analyzed periodic GPS observations of these networks to derive velocity vectors and principal components of crustal strain rates. Estimated horizontal velocities relative to Eurasia are found to be in the range of 18-22mm/yr with an uncertainty level at the order of 1-2mm/yr. The principal strain rate axes show a dominant extension in NE-SW direction, and mostly negligible SE-NW direction of contraction.