The multidisciplinary investigation of the creep, along the Hazar-Palu section of the DAF

Project Manager: Prof. Dr. Semih Ergintav

Abstract:
Surrounding the eastern Mediterranean region, in particular in our region, the general kinematics has been studied during the last 20 years. (Oral, 1992, Oral, 1995; McClusky et al., 2000; Reilinger et al., 2006; Özener et al., 2010;  Aktuğ et al., 2009; Aktuğ et al., 2013). In the recent years, the basic results of these studies has pioneered the increasing number of new studies focusing on present-day velocities along the major faults in Turkey, the North Anatolian (NAF) and the East Anatolian faults (EAF), detailed mapping of strain accumulation along the faults as well as creeping zones and monitoring the earthquake related deformations as a function of time (e.g. Tatar et al., 2011; Cakir et al. , 2005; Cakir et al. , 2012; Tiryakioğlu et al., 2013; Ergintav et al., 2009, 2013). Using geodetic methods, e.g. GPS (Global Positioning System) and InSAR (Synthetic Aperture Radar Interferometry), the properties of the faults that they were exposed to long- and short-term stress fields, were questioned and earthquake hazards were analyzed. However, most of the studies have been carried out for the NAF. Studies, along EAF, have been limited to only a few of studies focusing on the region around the triple junction between the Dead Sea Fault and the EAF using GPS (Mahmoud et al., 2012; Nocquet, 2012) and overall deformation along the EAF using InSAR (Cavalier and Jonsson, 2014).

Cavalier and Jonsson (2014) suggested a shallow locking depth along the EAF, target area in the proposal, and supported their results with an observation of very low seismicity during the recent centuries (Ambraseys, 1989; Ambraseys and Jackson, 1998; Ambraseys and Melville, 1995; Burton et al., 1984; Bulut et al., 2012) and magnetotelluric studies in the region (Türkoğlu, 2009). Therefore, they proposed a creeping mechanism for the upper crust section of the EAF.   Based on the fact that there is not a published study relating the surface deformations with the creep, they assumed that creep does not reach to the surface and it remains within the crust.  Similar to the creep observations along the Ismetpasa segment of the NAF (Çakır and diğ., 2005; Özener and diğ., 2013), investigation of creeping sections along the EAF is crucial to improve existing earthquake hazard models, which are related to the long term behavior of EAF (Nalbant and diğ., 2002; Çetin and diğ., 2003; Koçyiğit and diğ., 2003; Reilienger and diğ., 2006; Aksoy, 2007; Çetin, 2008; Çolak and diğ, 2011; Duman and Emre, 2013).

Using the permanent scatters approach of the InSAR method (PsInSAR) and the data of ENVISAT satellites, ESA (European Space Agency), the creep zones surrounding Hazar-Palu section have been preliminarily investigated resulting in a promising evidence for a local creep. Our results indicate that creep velocity reaches up to 10 mm/yr. Based on the GPS data resulting an average velocity of 10 mm/yr on EAF (Reilinger et al., 2006), our results claim that the creep reaches to the lower crust. As a result of the creep in upper crust, the strain accumulation will never occur and therefore creeping sections of the EAF will not produce a major earthquake. However, the stress and the earthquake potential will be increased at the tips of the creep zone. Obviously, locating the boundaries of the creeping zone along the fault is very important to elaborate on earthquake hazard assessment.

In this multidisciplinary proposal, our primary focus is to monitor potential variations of the creep velocity between Hazar-Palu, and to locate boundaries of the creeping zone in order to model mechanical behavior of the EAF. For this purpose, in order to control the creep as a result of InSAR analysis, in-situ observations will be realized by 4 fault perpendicular GPS profiles, which include 6 GPS sites to observe the creep in right position, with 5 surveys, during the proposed project. Turkey's National Permanent GPS Network-ACTIVE (TUSAGA-ACTIVE) data will be integrated to our database in order to