The Dead Sea is surrounded by some very active faults. Most of these are strike slip faults like the famous San Andreas Fault of California and, like the San Andreas Fault, they produce earthquakes.
The illustration below from Marco and Agnon, 1995, illustrates how we Geologists believe seismites are preserved in a column of sediments.
A. Sediments accumulate layer by layer as time passes.
B. When a sufficiently energetic earthquake is felt, the top layer right at the sediment-water interface is deformed.
C. After the earthquake, sediments continue accumulating layer by layer.