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 fault on the southern segment of the Arava Fault system in Israel. At least nine events are evident, beginning 37 ka. We study in detail the frequency-magnitude relation for the fault and develop a Bayesian analysis to compare the characteristic earthquake (CE) model and the Gutenberg-Richter (GR) model. Our analysis leads to the conclusion that there was a change in seismic behavior at about 14 ka. From -37 ka to - 14 ka, the seismic activity is best described by the CE model. From ~14 ka to the present, there is no strong indication favoring one model over the other; the earthquake record is somewhat more consistent with the classical GR equation than with the CE model. If one does assume that the CE model is appropriate for the younger 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: -14 ka.