Dating speleoseismites near the Dead Sea Transform and the Carmel fault: Clues to coupling of a plate boundary and its branch

Analysis of two published earthquake archives from the prehistoric Holocene provides insight into the interaction between two sectors of the Dead Sea Transform (DST) and its side branch, the Carmel fault (CF). The two sectors considered are the Dead Sea basin (DSB) and the Jordan Valley (JV). The archives are based on datable damaged cave deposits (speleoseismites). The first archive is based on a pair of caves in the Judean Hills, 40 km west of the DSB. The second archive is recovered from a cave in the city of Haifa adjacent to the CF. To identify possible patterns of interaction within the DSB-JV-CF fault system, we compare the seismic event ages obtained from the two study sites using the same proxy, namely speleoseismites. The two archive sites are potentially affected by the same fault system, yet separated by 110 km. A very strong seismo-tectonic event affecting the entire region would give the same ages (to within dating uncertainty) at both archives. Separate, local events from either sector would record separately in either archive. We compare results from these studies with on-fault and archaeological paleoseismic studies from the CF and the Jordan Valley.Nine prehistoric Holocene speleoseismites identified in Denya Cave, Haifa, were interpreted to represent two seismic events (4.8±0.8 ka and 10.4±0.7 ka). For the same time period, six speleoseismites identified at the Judean Hills caves (Soreq-Har-Tuv caves) cluster to two events (∼5 ka, 8.6 ka). Together with other paleoseismic studies from the CF and JV regions, temporal correlation between cave archives implies coupling between the main fault sectors (DSB, JV) and CF branch. Specifically, an event at ∼5 ka is well-recorded at both the Haifa and Judean Hills caves. However, the penultimate Haifa cave event at ∼10.5 ka seems to be limited to the northern region. The ∼5 ka event could be a CF rupture or a very large JV-DSB event, or a seismic event on one of the faults followed quickly by an event on one of the others. Using a simplified model, we list possible earthquake scenarios in order to better understand the tectonic regime of the region. Uncertainties may prevent resolution of close events, but quiescent intervals and clustered earthquake events are resolved. The quiescent intervals identified for the largest events in the seismic cycle are between ∼10 ka and ∼5 ka in the cave in Haifa, and from ∼5 ka to the historical period in the Judean Hills.