AN INDICATION OF TIME-DEPENDENT SEISMIC BEHAVIOR - AN ASSESSMENT OF PALEOSEISMIC EVIDENCE FROM THE ARAVA FAULT, ISRAEL

We discuss the implications of 56 kyr of paleoseismic data from a faul t on the southern segment of the Arava Fault system in Israel. At leas t nine events are evident, beginning 37 ka, We study in detail the fre quency-magnitude relation for the fault and develop a Bayesian analysi s to compare the characteristic earthquake (CE) model and the Gutenber g-Richter (GR) model. Our analysis leads to the conclusion that there was a change in seismic behavior at about 14 ka. From similar to 37 ka to similar to 14 ka, the seismic activity is best described by the CE model. From similar to 14 ka to the present, there is no strong indic ation favoring one model over the other; the earthquake record is some what more consistent with the classical GR equation than with the CE m odel. If one does assume that the CE model is appropriate for the youn ger episode, then there is evidence of a change in the characteristic magnitude. Thus, there is evidence of a change in earthquake behavior on the fault segment similar to 14 ka.