Action 5.2.4 : Uncertainty in GMPEs – effect of non-ergodic models

Technical Issue

Regions with large data sets show how different non-ergodic GMPEs can be from global GMPEs. Moving to non-ergodic GMPEs requires estimation of the epistemic uncertainty in the region-specific effects. The PSHA program needs to be revised to use non-ergodic GMPEs with epistemic uncertainty

Proposed Approach

Develop an initial non-ergodic GMPE for California. Modify the Haz45 program to use fully non-ergodic GMPEs (spatially varying path and site scaling effects in the GMPEs).


  • Suite of Non-ergodic GMPEs for California
  • Modified version of Haz45