Determination of Aseismic Creep or Strain Field on the Main Marmara Fault

Plate motion affecting the Earth's crust have occurred for millions of years. Determination of strain accumulation based on the plate motion is commonly monitored with GPS in recent years. The North Anatolian Fault (NAF) Zone, which is one of the fastest faults in the world, extends along all North Anatolia from Bingöl to Saros Gulf. Several destructive earthquakes occurred there, such as Izmit (in 1999, Mw=7.4) and Duzce (in 1999, Mw=7.2) in last century. The NAFZ is dividing into southern and northern branches to the east of Marmara region and the Northern branch (Main Marmara Fault-MMF) is crossing the Marmara Sea, starting in from the Gulf of Izmit - Adapazarı and reaching the Gulf of Saros. According to recent studies, the MMF is the largest unbroken part of the fault and is divided into segments (among which the Central Marmara-CM and Prince's Island-PI segments). The determination of the deformation accumulated on the MMF has become extremely important especially after the 1999 Izmit earthquake. Recent studies have demonstrated that the Prince's Island segment is fully locked. However, studies that are focused on the Central Marmara segment, that is located offshore Istanbul, a giant metropole that has more than 14 million population, do not conclude about the presence of a seismic gap, capable of generating a big earthquake. Therefore, in the scope of this study, a new GPS network will be established at short and long distance from the Main Marmara Fault, to densify the existing GPS network. several campaign measurements will be necessary to compute a velocity field. The velocity field will reveal the compression and variations of accumulation rate on the fault. Also, the amount of aseismic creep deep within the fault will be determined using Elastic Displacement Modeling method, allowing to conclude about the existence of a seismic gap on the Main Marmara Fault originated from aseismic deformation or not.