ORIGINAL PAPER Quantitative analysis of relative tectonic activity in the Acıgöl fault, SW Turkey Savaş Topal 1 Received: 17 January 2018 /Accepted: 16 April 2018 # Saudi Society for Geosciences 2018 Abstract This study was conducted in order to determine the relative tectonic activity of the Acıgöl Fault using geomorphic indices. The Acıgöl Fault is approximately 50 km long and was separated into four segments. For this purpose, the following geomorphic indices have been used: (1) mountain-front sinuosity (S mf ), (2) valley floor width-to-valley height ratio (V f ), (3) basin asymmetry factor (AF), and (4) hypsometric curve and integral (Hi). When the results of S mf and V f are evaluated, the uplift ratio was calculated as > 0.5 mm year -1 in the middle part of the fault, namely in the second and third segments, whereas this ratio is 0.5– 0.05 mm year -1 along the NE nad SW margins of the fault. The Acıgöl Fault is normal fault based on both relative tectonic activity is moderate to high and downthrow is high in the middle part of the fault and low in the margins. In general, the Acıgöl Fault has relatively moderate to high tectonic activity and when the length of the fault is taken into consideration, generally speaking, the Acıgöl Fault has relatively moderate to high tectonic activity, and when the length of the fault is taken into consideration, it was concluded that the fault could produce a high-magnitude earthquake in the future. Keywords Acıgöl fault . SW Turkey . Relative tectonic activity . Geomorphic indice Introduction The studies, made in order to reveal the relationship between geomorphological processes and tectonics, are the main topic of tectonic geomorphology (Mayer 1986). Previous studies have formulated geomorphic indices for use in tectonic geo- morphology studies and the calculation of these indices (Strahler 1952; Bull 1977; Bull and McFadden 1977; Rockwell et al. 1984; Hare and Gardner 1985; Cox 1994; Keller and Pinter 2002; Silva et al. 2003; El Hamdouni et al. 2008). In calculation of these indices, digital elevation model, topographic maps, satellite images, and field data are used (Keller and Pinter 2002; Silva et al. 2003; Bull 2007; Pérez- Peña et al. 2010). Geomorphic indices are important tools to determine the extent of relative tectonic activity in a particular area and to analyze landscapes (Keller 1986). Although there are previous studies about the origin of Acıgöl Basin, lake sediments, climate, and sedimentology, there are no studies on the seismicity, paleoseismology, and active tectonics of the Acıgöl Fault which bounds the basin in the south. In this study, recent and important information about the active tectonics of the Acıgöl Fault will be provided. This study aims to determine the tecton- ic activity of the Acıgöl Fault and uplifting ratio using the mountain front sinuosity (S mf ), valley floor width to valley height ratio (V f ), basin asymmetry factor (AF), hypsomet- ric curve and integral (Hi). Geological settings Acıgöl graben is one of the NE-SW trended grabens in SW Anatolia, Turkey. The base of the Acigöl graben, which is 50 km long and 11 km wide, is formed by ultramafic rocks and Mesozoic-Paleogene carbonates (Göktaş et al. 1989; Şenel 1997; Konak and Şenel (2002) (Fig. 1). Basement rocks that consist of western part of the Torid orogen belong to the Lycian Nappes. Alloctonus rocks units located along the south margin of the basin are represented by the Triassic-Jurasic dolostones, dolomitic limestones, late Jurassic-Cretaceous limestones, siliciclatic rocks, and late Cretaceous peridotite (Alçiçek 2009) (Fig. 1). * Savaş Topal savastopal@pau.edu.tr 1 Engineering Faculty, Department of Geological Engineering, Pamukkale University, Kınıklı Campus, 20017 Denizli, Turkey Arabian Journal of Geosciences (2018) 11:198 https://doi.org/10.1007/s12517-018-3545-z