Probabilistic seismic hazard analysis (PSHA) is a methodology that estimates the likelihood that various levels of earthquake-caused ground motions will be exceeded at a given location in a given future time period. The results of such an analysis are expressed as estimated probabilities per year or estimated annual frequencies.
While there is considerable information on earthquake ground motions and potential future locations of earthquakes, there is also considerable uncertainty in the inputs to the analysis.
Recognizing the need to identify and address these uncertainties as part of a PSHA, the Senior Seismic Hazard Analysis Committee (SSHAC, 1997) established the goal for all PSHA’s to quantitatively assess these uncertainties and to represent the distribution of the informed technical community of alternative models and parameter values.
Seismic Failure Modes
Sliding failure through weak lift line
Liquefaction of dam or foundation
Cracking from severe shaking
Surface fault displacement through the
Overtopping from landslide failure into