The Time-Dependent Method for Probabilistic Fault Displacement Hazard Analysis (PFDHA-td)

Coseismic surface displacement can cause major damage to buildings located on faults. Therefore, it is important to quantitatively evaluate the future surface displacement of active faults. The commonly used deterministic evaluation methods often tend to overestimate surface displacement values, so researchers are working toward probabilistic fault displacement hazard analysis (PFDHA). However, the PFDHA assumes that earthquakes occur equally in time, which is not consistent with the physical mechanism of earthquake occurrence. Elastic rebound theory and paleoseismic research results show that the accumulation and release of energy in the crustal medium have cyclical characteristics. In this study, using two parameters, the strong earthquake recurrence period (TRP) and strong earthquake elapsed time (tet), of active faults, the displacements of active faults with different TRP and tet under different exceedance probabilities are obtained. The calculation results indicate that the surface displacement hazard of the weakly active and extremely weakly active faults in the Holocene does not need to be considered; for the moderately and strongly active faults in the Holocene, the surface displacement result is lower than that provided by the deterministic method. According to the importance of the project, the calculation results of the PFDHA-td method under different exceedance probabilities are selected.