Slip along the Sultanhani Fault in Central Anatolia from deformed Pleistocene shorelines of palaeo-lake Konya and implications for seismic hazards in low-strain regions
Authors:Melnick, DanielYildirim, CengizHillemann, ChristianGarcin, YannickCiner, AttilaPerez-Gussinye, MartaStrecker, Manfred R.
Source:GEOPHYSICAL JOURNAL INTERNATIONAL
Volume:209
Published:2017
Document Type:Article
Abstract:Central Anatolia is a low-relief, high-elevation region where decadal-scale deformation rates estimated from space geodesy suggest low strain rates within a stiff microplate. However, numerous Quaternary faults have been mapped within this low-strain region and estimating their slip rate and seismic potential is important for hazard assessments in an area of increasing infrastructural development. Here we focus on the Sultanhani Fault (SF), which constitutes an integral part of the Eskisehir-Cihanbeyli Fault System, and use deformed maximum highstand shorelines of palaeo-lake Konya to estimate tectonic slip rates at millennial scale. Some of these shorelines were previously interpreted as fault scarps, but we provide conclusive evidence for their erosional origin. We found that shoreline-angle elevations estimated from differential GPS profiles record vertical displacements of 10.2 m across the SF. New radiocarbon ages of lacustrine molluscs suggest 22.4 m of relative lake-level fall between 22.1 +/- 0.3 and 21.7 +/- 0.4 cal. kaBP, constraining the timing of abrupt abandonment of the highstand shoreline. Models of lithospheric rebound associated with regressions of the Tuz Golu and Konya palaeolakes predict only similar to 1 m of regional-scale uplift across the Konya Basin. Dislocation models of displaced shorelines suggest fault-slip rates of 1.5 and 1.8 mm yr(-1) for planar and listric fault geometries, respectively, providing reasonable results for the latter. We found fault scarps in the Nasuhpinar mudflat that likely represent the most recent ground-breaking rupture of the SF, with an average vertical displacement of 1.2 +/- 0.5 m estimated from 54 topographic profiles, equivalent to a M similar to 6.5-6.9 earthquake based on empirical scaling laws. If such events were characteristic during the ultimate 21 ka, a relatively short recurrence time of similar to 800-900 yr would be needed to account for the millennial slip rate. Alternatively, the fault scarp at Nasuhpinar might represent a larger earthquake requiring more frequent smaller events to account for the millennial rate. The relatively fast slip rate of the SF over the past 21 ka is unlikely to have persisted over longer timescales and might reflect spatiotemporal variations in deformation rates within kinematically-linked fault systems within Central Anatolia, or a transient perturbation to the local stress field or fault strength. Such perturbation might have been related to climatically controlled changes in surface and near-surface loads and by interactions among the different tectonic processes that have been proposed to drive the overall slow uplift and associated extension in the Central Anatolian Plateau.
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Reprint Address:Melnick, D (corresponding author), Univ Potsdam, Inst Erd & Umweltwissensch, Potsdam, Germany.; Melnick, D (corresponding author), Univ Austral Chile, Inst Ciencias Tierra, Valdivia, Chile.
Addresses:[Melnick, Daniel; Hillemann, Christian; Garcin, Yannick; Strecker, Manfred R.] Univ Potsdam, Inst Erd & Umweltwissensch, Potsdam, Germany. [Melnick, Daniel] Univ Austral Chile, Inst Ciencias Tierra, Valdivia, Chile. [Yildirim, Cengiz; Ciner, Attila] Istanbul Tech Univ, Eurasia Inst Earth Sci, Istanbul, Turkey. [Perez-Gussinye, Marta] Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen, Germany.
E-mail Addresses:melnick@geo.uni-potsdam.de