Pre-instrumental earthquakes along the Dead Sea rift

Abstract

The Dead Sea rift offers a wealth of information about pre-instrumental earthquakes. The types of potential archives include historic seismicity, archaeological sites, disturbed beds in lake deposits, rockfalls within caves as well as on free slopes, and displaced marine terraces. The rich historical archive is useful as a key for deciphering the geological archives. Of the geological archives developed for the Dead Sea rift, lake sections stand out due to the long periods covered with high resolution. Lake deposits contain long and potentially continuous archives of the environment, and of earthquakes in particular. The Holocene drop in Dead Sea level, accentuated with a fast anthropogenic drop, have triggered incision and outcrop formation, permitting access and direct investigation of archives. The ongoing analysis of cores from lake drill-holes will augment the continuity of the archive. The historical information spans periods that exceed the seismic cycle of individual fault segments. One of the provoking results of the comparisons of historical versus geological archives of earthquake activity is the significant difference in the apparent length of the earthquake cycle, where prehistorical data indicates long quiescence periods. This suggests that even the long historical record of the Levant does not encompass the full earthquake cycle along the entire Dead Sea fault. This result underscores the significance of paleoseismic research for the understanding of earthquake-fault mechanics and for hazard assessment.