Present-day and late Quaternary crustal deformation along the southern Dead Sea Fault System, Jordan

Abstract

Theoretical models of the earthquake cycle predict that crustal rheology may lead to differences between short-term crustal deformation rates (decadal time scales) and long-term fault slip rates (Holocene to late Pleistocene time scales). This study investigates fault kinematics along the southern Dead Sea fault using tectonic geodesy and late Quaternary slip estimates. The Dead Sea fault is the left-lateral transform bounding the Arabia and Sinai plates in the eastern Mediterranean region. Two main segments comprise the southern DSF: the Wadi Araba and Jordan Valley faults. These two main fault branches are separated by a left step-over that forms the Dead Sea basin. This study incorporates new GPS measurements in Jordan (survey-mode and continuous), as well as recently published data within Israel. The application of elastic dislocation models produced slip rates of 4.8 ± 0.1 mm/yr and 4.7 ± 0.1 mm/yr for the Wadi Araba and Jordan Valley faults, respectively. Effective locking depths also varied along strike, ranging from 9 ± 3 km and 16 ± 6 km along the Wadi Araba and Jordan Valley faults, respectively. Previously published geologic slip rates range from 2-20 mm/yr. For a more robust comparison of short-term and long-term slip rates, this study re-evaluates published geomorphic data from six sites along the southern DSF using a standardized statistical analysis. Our statistical analyses reduce the slip rate uncertainties, and suggest a slip rate of 4.5-5.0 mm/yr for the past 100 ka. In addition to implications for regional earthquake hazard, the consistency of the slip rates suggests that of a relatively stiff lower crust.