Monitoring aseismic creep trends in the Ismetpasa and Destek segments throughout the North Anatolian Fault (NAF) with a large-scale GPS network

Abstract

The North Anatolian Fault Zone (NAFZ) is an intersection area between the Anatolian and Eurasian plates. The Arabian Plate, which squeezes the Anatolian Plate from the south between the Eurasian Plate and itself, is also responsible for this formation. This tectonic motion causes the Anatolian Plate to move westwards with almost a 20 mm yr(-1) velocity, which has caused destructive earthquakes in history. Block boundaries that form the faults are generally locked to the bottom of the seismogenic layer because of the friction between blocks and are responsible for these discharges. However, there are also some unique events observed around the world, which may cause partially or fully free-slipping faults. This phenomenon is called aseismic creep and may occur through the entire seismogenic zone or at least to some depths. Additionally, it is a rare event in the world located in two reported segments along the North Anatolian Fault (NAF), which are Ismetpasa and Destek. In this study, we established GPS networks covering those segments and made three campaigns between 2014 and 2016. Considering the long-term geodetic movements of the blocks (Anatolian and Eurasian plates), surface velocities and fault parameters are calculated. The results of the model indicate that aseismic creep still continues with rates of 13.2 similar to 3.3 mm yr(-1) at Ismetpasa and 9.6 similar to 3.1 mm yr(-1) at Destek. Additionally, aseismic creep behavior is limited to some depths and decays linearly to the bottom of the seismogenic layer at both segments. This study suggests that this aseismic creep behavior will not prevent medium- to large-scale earthquakes in the long term.