HR: 14:20h
AN: S13C-03 INVITED     [Abstracts]
TI: PSHA: What Next?
AU: * Lomnitz, C
EM: cinna@prodigy.net.mx
AF: Institute of Geophysics, National University of Mexico (UNAM), Mexico, DF 04510 Mexico
AB: There are some weighty reasons for doubting that PSHA is a procedure in good scientific standing. Seismic hazard evaluations may be needed for regulatory use, but the problem is how to overcome serious limitations in fundamental scientific knowledge and in local and regional observational data. PSHA appears to be going considerably beyond a simple recognition or acknowledgment of the objective facts at hand. It appeals to an evaluation of the state of knowledge of the seismic hazard by one or more experts... [where every expert must consider] all of the (aleatory) variabilities and all of the (epistemic) uncertainties. The jargon of aleatory and epistemic supersedes what is commonly called the error of statistical measurements and the scatter of expert opinion. This sleight of hand makes legitimate discrepancies among scientists look like random variations from some hypothetical consensus of the informed technical community, called the community distribution. Actually there is no evidence that the opinions of experts, or of authors in the literature, can have a distribution in the probability sense. Probabilistic predictions cannot be better than the data. Deterministic procedures may be preferable to probabilistic ones when the data are scarce and uncertain. As William Feller (1966) said, it depends on the type of information one seeks and the details one is prepared to skip. Feller, W. (1966). An Introduction to Probability Theory and Its Applications, Preface to Vol. 2 (John Wiley & Sons, New York).
DE: 6309 Decision making under uncertainty
DE: 6615 Legislation and regulations (6324)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005