Seismic cycle, long-term faulting behavior and slip rate variations along the Dead Sea Fault (Jordan)

The recurrence of large and destructive earthquakes along major fault systems is key to understanding the seismic cycle, the driving mechanism and forecast future behavior. We study the ~ 110-km-long Jordan Valley Fault segment (JVF) of the North-South trending Dead Sea Transform Fault and plate boundary by means of two independent approaches: i) the build-up of a paleoseismic catalogue of surface-rupturing events for the last 14 kyr, and ii) the construction of a history of slip rate over the last 48.5 kyr from different generations of left-lateral offset streams of the late Pleistocene and Holocene Lissan lacustrine deposits. Firstly, we combine published historical data, re-appraised archaeological data and paleoseismic trenching to produce and unprecedentedly complete catalogue of large (Mw > 7) earthquakes with at least 13 events in the last 14 kyr. The average ~1000 yrs recurrence interval presents large variations from 300 to more than 1500 yrs, with the various datasets intersecting and completing each other. Secondly, we present a detailed map of the active fault trace that intersects a set of 20 gullies. Stream incisions are classified as a function of their depth and relative age and characterized in terms of cumulative offsets. Absolute ages are obtained from paleoclimatic analysis of lacustrine deposits. Using the numerous isotopic dating of lacustrine deposits, lake-level fluctuations and extreme rainfall episodes, we obtain an average 4.9 mm/yr slip rate with extreme values of 3.5 and 11 mm/yr. Our results indicate slip rate variations and provide evidence for episodic faulting behavior. Both approaches indicate that the JVF encounters periods of increased seismic activity which suggests episodicity or mode-switching. Reduced recurrence intervals and/or larger co-seismic slip (and magnitudes) are required to account for observations as suggested by GPS observations (4.5 mm/yr) and seismic moment summation. The JVF has accumulated 3.5 m to 5 m of slip deficit after the AD 1033 earthquake and may be the site for a large earthquake in the near future.