ON THE HANDLING OF UNCERTAINTIES IN ESTIMATING THE HAZARD OF RUPTURE ON A FAULT SEGMENT

Uncertainties in data and parameter values have often been ignored in hazard estimates based on historic and prehistoric records of rupture on fault segments. A mixture of distributions approach is appropriate to handle uncertainties in parameters of recurrence time distributions estimated from the geological and historical earthquake record of a f ault segment, and a mixture of hazards approach is appropriate for dat a uncertainties and for uncertainties in parameters estimated from a s et of similar faults. The former approach admits updating of the distr ibutions for uncertainty as time passes. The aim is to present the haz ard as a single value which takes account of both data and parameter u ncertainties, conditional only on modeling assumptions. The proposed m ethods axe described in detail for the exponential and lognormal recur rence time models for fault-rupturing earthquakes and applied, by way of illustration, to selected fault segments, namely, the Mojave segmen t of the San Andreas fault, California, and the Wellington-Hutt Valley segment of the Wellington fault, New Zealand.