Seismic potential of the Dead Sea Fault in the northern Gulf of Aqaba-Elat: New evidence from liquefaction,seismic reflection, and paleoseismic data

摘要

The cities of Elat, Israel and neighboring Aqaba, Jordan are major economic, cultural, and seaport centers. They are located on the northern shore of the Gulf of Aqaba/Elat (GAE) directly on the Dead Sea Transform. Yet the precise location of the fault trace and its tectonic activity are lacking. The interpretation of seismic reflection profiles across the GAE beach and paleoseismic trench data located 2.2 km north of the shoreline provide evidence that the active offshore mapped Avrona Fault extends onland along the eastern side of the Elat Sabkha (mudflat), where three prominent fault strands crosscut the sedimentary fill. Mismatch of reflector geometry across the faults and flower structures indicate strike-slip faulting with a normal-slip component. Subsurface data from two trenching sites provide evidence for a minimum of two surface ruptures and two paleoliquefaction events. Faulting is constrained by radiocarbon dating for an Event 1 between 897 and 992 CE and Event 2 after 1294 CE. We suggest that the historically documented 1068 CE, and at least one later earthquake in 1458 or 1588 CE, ruptured the Elat Sabkha site. Based on fault mapping, we suggest a minimum value of M 6.6 for the 1068 CE earthquake. Whereas no surface rupture was observed for the 1212 CE historical earthquake, fluidized strata radiocarbon dated to before 1269-1389 CE identified as paleoliquefaction may be attributed to it. Two liquefaction sand-blows mapped in the trench likely formed after 1337 CE and before 1550 CE, which possibly occurred at the same time as in the second faulting event. Our data suggest that no large event occurred along the Avrona segment in the past ～430-550 years. Given a ～ 5 mm/yr slip rate, we conclude that a significant period of time passed since the last surface rupturing on the Avrona Fault, increasing its seismic potential.