LAUSR

Abstract. We evaluate rockfall hazard for the town of Qiryat-Shemona, northern Israel, situated alongside the Dead Sea Transform, at the foot of the Ramim escarpment. Boulders of 1 m 3 to 125 m 3 are scattered on the slope above town, while historical aerial photos reveal that before town establishment, numerous boulders had reached the town premises. For the hazard analysis we first mapped the rockfalls, their source and their downslope final stop-sites, and compiled the boulder size distribution. We then simulated the probable future rockfall trajectories using the field observed data to calibrate the simulation software by comparing simulated vs mapped boulders stop-sites along selected slopes while adjusting model input parameters for best fit. The analysis identified areas of high rockfall hazard at the south-western quarters of the town and also indicates that in the studied slopes, falling blocks would stop after several tens of meters where the slope angle is below 10°. OSL age determination of several past rockfall events in the study area suggests that these rockfalls were triggered by large (M > 6) historical earthquakes. Nevertheless, not all large historical earthquakes triggered rockfalls. Simulations show that downslope reach of the blocks is not significantly affected by the magnitude of seismic acceleration. Considering the size distribution of the past rockfalls in the study area and the reoccurrence time of large earthquakes in the region, the probability to be affected by a destructive rockfall within a 50 year time-window is of less than 5 %.