MARine Earthquake Gap Assessment and Monitoring for Istanbul – MAREGAMI2016

The Sea of Marmara has been in the focus of national and international research groups for tectonic, paleoseismological and paleoceanographic studies because of its tectonic setting on the North Anatolian Fault (NAF), its earthquake risk and its location on a gateway between the Mediterranean and the Black Sea. After the 1912 Mürefte and 1999 Kocaeli earthquakes, the presence of a seismic gap in the Sea of Marmara and its rupture with a M>7 earthquake in the near future are now accepted by most authorities. Determination of the NAF segment(s) constituting the seismic gap and the magnitude of the earthquake(s) that could be caused by their rupture are of vital importance for earthquake risk assessment for the Istanbul area specifically and for the Marmara region in general. Within the framework of 15 years of continuous collaboration between Turkish and French research groups, we carried out a marine survey in the Sea of Marmara during October-November 2014 with R/V Pourquoi Pas?. During this 20-day cruise we set up an acoustic ranging geodetic experiment along the Central High segment of NAF and deployed ocean bottom seismometers (OBS). This proposal will analyze the cores and the data generated by the geodetic experiment and the OBSs, with the following objectives of: (1) Evaluating the possibility to measure creep on the Central Marmara segment by analyzing the data from the in-situ marine acoustic-ranging experiment and from far-field continuous land-based (2) Acquiring new hydrologic data and bottom pressure time series to eliminate the effect of the water column on acoustic travel time variability (3) Improving the fine-scale distribution of the near-fault seismicity. The OBS data will be integrated with land-network data to better characterize the near-fault seismicity (4) Designing an optimal submarine monitoring observatory to be implemented in the Sea of Marmara. The design will be based on the results from these seismological data integration, geodetic experiments and bottom pressure recordings, and from previous submarine equipment deployments, which mostly focused on fluid emission sites. This collaborative project consists of five work packages and involves 7 research groups : 5 from France (Ifremer, LDO, CEREGE, ISTERRE, LIENs) and 2 from Turkey (ITU and KOERI).