Slip Partitioning Across Subparallel Strands of the North Anatolian Fault in the Marmara Region

Summary Marmara Region hosts a substantial part of the inhabitants in Turkey, more than 30% of the total population in the cities of Istanbul, Bursa, and Kocaeli. This region has experienced several large earthquakes in the past and is still under threat of destructive earthquakes in the future. There, subparallel strands of the North Anatolian Fault (NAF) expand into the region, distributing the earthquake hazards across the whole region. Thus, it is a key issue to investigate how the tectonic process is distributed between these subparallel strands to discriminate their individual earthquake hazards. In this context, we used GPS slip rates to quantify the slip partitioning of the subparallel strands of the fault system. In addition to available slip rates compiled by Bulut et al. (2019) and Kreemer et al. (2014), we analyzed 71 GPS sites (51 continuous and 20 campaign-based) to intensify the GPS network in the region. GPS observations reveal 81.7%, 7.7%, and 10.7% slip ratios for northern, middle, and southern strands. Time series analysis for four continuous GPS stations in the western Marmara Region also confirms these ratios.