817-YEAR-OLD WALLS OFFSET SINISTRALLY 2.1 M BY THE DEAD-SEA TRANSFORM, ISRAEL

Archeological excavations in the Crusader Ateret Fortress near the Jor dan River exposed E-W trending walls displaced sinistrally up to 2.1 m by the Dead Sea transform fault. A water duct, probably of Crusader a ge, is also offset sinistrally across the fault by about 1-2 m, but ne wer water ducts parallel to the former one show no displacement. The m aximum width of the fault zone is about 10 m. Post-Crusader structures show significantly less deformation, and together with the low seismi c activity, suggest there has been negligible creep. It is therefore c onceivable that in this particular fault segment, stress is occasional ly relieved by strong destructive earthquakes associated with surface ruptures. Historical accounts include descriptions of post-Crusader ea rthquakes in the northern part of Israel in A.D. 1202, 1546, 1759, and 1837. These events caused destruction and casualties over large areas . We conclude that most of the displacement of the Ateret Fortress wal ls occurred during one of these strong earthquakes, probably that of 1 202 A.D., and some additional offset occurred during subsequent events . The associated magnitude is estimated at 6.5-7.1. The Ateret site is extremely valuable for paleoseismic studies in general, and assessmen t of seismic hazard to nearby population centers in particular, as the re is. an abundance of well-dated man-made structures and a small numb er of candidate earthquakes. (C) 1997 Elsevier Science Ltd.