Integrated Paleoseismic Chronology of the Last Glacial Lake Lisan: From Lake Margin Seismites to Deep-Lake Mass Transport Deposits

Seismically disturbed sedimentary sequences (seismites) in the last glacial (70–14 ka) Lisan Formation are exposed in the marginal terraces of the Dead Sea and recovered from sedimentary core drilled by the International Continental Scientific Drilling Programs at the depocenter of the lake at water depth of 300 m. The core reveals various types of centimeter- to meter-scale disturbed lake sediments: turbidites, homogenites, slumps, and other deformations, interspersed with undisturbed lamination. The transported sediments comprise a main source of the thickness tripling of the Lisan Formation at the depocenter of the lake compared to the margins. Excluding (mass transport deposits MTDs) from chronology yields a normal, event-free age-depth model for core. Moreover, time intervals of units missing at the exposed sections of the lake margin are synchronous with intervals of mass transport deposits (MTDs) at the deepest lake floors. In the deep core, the recurrence interval range of MTD with thickness > 1 cm is ~ 100–300 years, while that of the thick MTD (>50 cm) is ~ 2,500 years, twice the recurrence interval of the seismites at the lake's margins. The ~1,000 year recurrence at the lake's margins lies within the ranges that have been calculated for ~M6.5–7 earthquakes. The significantly higher figure shown by depocenter core suggests activity on various faults and the response of the lake sediments in the entire Dead Sea basin. Overall, an unprecedented chronology of seismic activity was achieved for the late Pleistocene Lisan Formation providing a framework of earthquake activity in the vicinity of the Dead Sea basin during the period of the last high lake stand.