Slip rates and locking depth variation along central and easternmost segments of North Anatolian Fault

B Aktuğ,M Peyret,A Doğru,H Özener

doi:10.1093/gji/ggv274

Abstract

While the kinematics of Anatolia plate and the North Anatolian Fault System (NAFS) has been studied extensively, the slip rate and locking depth along the NAFS are usually assumed constant in the analyses due to the lack of sufficient data. This is also partly due to the reasonably good fit of Euler small circle and partly due to the lack of spatial resolution of observations to determine slip rates independently from locking depths. On the other hand, recent geodetic studies show a contrast for locking depth between Marmara and other parts of the NAFS, implying a non-uniform locking depth across the NAFS. In this study, we analyse new GPS data and homogenously combine available data sets covering the eastern part of the NAFS to form the most complete data set. In particular, we incorporate the first results of Turkish Real-Time Kinematic GPS Network (CORS-TR) into our data set. A detailed analysis of three profiles within the NAFS reveals an increase of locking depth in the middle profile to 19.1 ± 3.4 km from 11.9 ± 3.5 km in the easternmost profile while the slip rate is nearly constant (20–22 mm yr−1), which implies a variation of strain rate of ∼100 nanostrain yr−1. Assuming a constant locking depth throughout whole NAFS gives an average locking depth of 14.3 ± 1.7 km. Our best estimates of slip rates in block modelling which takes the variation of locking depths into account are in the range between 22.5 and 22.8 mm yr−1 over eastern part of the NAFS.

Highlights

North Anatolian Fault System (NAFS) is a ∼1500 km long strikeslip fault system delineating the boundary between Eurasia and Anatolia plates (Barka & Kadinsky-Cade 1988)
GPS studies focusing on the general tectonic framework of Anatolia motion lack sufficient spatial resolution near individual segments of the NAFS and usually gives an upper bound for the slip rates of the NAFS (McClusky et al 2000; Reilinger et al 2006; Aktuget al. 2013a)
In simultaneous estimation of the slip rates and locking depths using the profiles a–c, the slip rates were found to be 21.5 ± 1.2, 21.4 ± 1.3 and 19.8 ± 2.3 mm yr−1 for the segments a, b and c, respectively. Such nearly constant slip rates are consistent with the Holocene slip rates of 18–21 mm yr−1 (Hubert-Ferrari et al 2002; Kozacı et al 2007; Kozacı et al 2009) as opposed to the previous estimates of 24 ± 1 mm yr−1

Summary

INTRODUCTION

North Anatolian Fault System (NAFS) is a ∼1500 km long strikeslip fault system delineating the boundary between Eurasia and Anatolia plates (Barka & Kadinsky-Cade 1988). The slip rates of the NAFS have been studied at various scales by GPS and InSAR Recent regional studies with relatively dense GPS arrays show that the locking depth and slip rate vary significantly over the NAFS (Ozener et al 2010; Yavasoglu et al 2011; Tatar et al 2012).

CORS-TR

DISCUSSION

CONCLUSION