Late Pleistocene and Holocene slip rate of the Northern Wadi Araba fault, Dead Sea Transform, Jordan

The Wadi Araba Valley is a morphotectonic depression along part of the Dead Sea Transform (DST) plate boundary that separates the Arabian plate on the east from the Sinai subplate on the west. The Wadi Araba fault (WAF) is th e main strike-slip faults one of between the Gulf of Aqaba and the E-W tren ding Khunayzira (Amatzayahu) fault that bounds the southern end of the Dead Sea. Just south of the Dead Sea, the WAF cuts across several generations o f alluvial fans that formed on tributaries to the Wadi Dahal after the regr ession of Late Pleistocene Lake Lisan ca. 15 ka. Geomorphic and stratigraph ic evidence of active faulting, including left-laterally offset stream chan nels and alluvial-fan surfaces, yielded fault slip-rate data for the northe rn segment of WAF. Typical cumulative displacements of 54 m, 39 m, and 22.5 m of stream channels and alluvial-fan surfaces across the fault were measu red from detailed geologic and topographic mapping. The 54 m offset of the oldest alluvial-fan surface (Q(f1)) occurred after the final lowering of La ke Lisan (16-15 ka) and before 11 ka yielding a slip-rate range of 3.4 mm/y r to 4.9 mm/yr. Based on radiocarbon ages of charcoal and landsnail shell s amples from the buried Q(f2) alluvial-fan deposits exposed in trenches exca vated across the fault, the 39 m and 22.5 m offsets occurred after 9 ka and 5.8 ka, respectively. These data yield a slip-rate range between 3.9 mm/yr and 6.0 mm/yr. The small variability in these slip-rate estimates for diff erent time periods suggests that the northern Wadi Araba fault has maintain ed a relatively constant slip rate in the past 15 ka. We calculate an avera ge slip rate of 4.7 +/- 1.3 mm/yr since 15 ka based on the three separate d isplacements and age estimates. Five separate offsets of 3 m were measured from gully bends and the offset of small fault-scarp alluvial fans. These d isplacement data suggest a coseismic slip of 3 m in the last earthquake, or a cumulative slip of 3 m in the past few earthquakes. A maximum slip of 3 m correspond to a Mw 7 earthquake that ruptures about 49 km of fault length . Using an average slip rate of 4.7 +/- (1).3 mm/yr together with a 3-m sli p-per-event suggests a maximum earthquake recurrence interval of this fault segment of 500 to 885 years.