The hazard in using probabilistic seismic hazard analysis for engineering
Ellis L. Krinitzsky
Waterways Experiment Station, Geotechnical Laboratory, Vicksburg, MS, United States
Both the deterministic and probabilistic methods of seismic hazard analysis serve necessary purposes. Probability is needed to obtain operating basis earthquakes, to perform risk analyses, to prioritize projects, and for assigning recurrence estimates to deterministic earthquakes. The probability for these purposes is used as a relativistic measure. The problem with seismic probability is that it relies on the Gutenberg-Richter b-line, which has severe shortcomings. There are corrections that can be applied, which attempt to remedy the problems. Data are introduced for paleoseismic events, characteristic earthquakes, and slip-rate, or judgments are introduced from logic trees, multiple expert opinions, and de-aggregation of E-values. Unfortunately, none are equal to the task. The probabilistic seismic hazard analyses remain fundamentally limited in their dependability. However, the deterministic method can provide evaluations that are at a practical level for engineering. Engineering design must be done deterministically if one is to have seismic safety coupled with good engineering judgement. The design for critical structures, those for which failure is intolerable, such as dams, nuclear power plants, hazardous waste repositories, etc., must be based on maximum credible earthquakes, obtained by deterministic procedures, in order to assure their seismic safety.
This record provided courtesy of AGI/GeoRef.
