Abstract
Probabilistic seismic‐hazard analysis (PSHA) is commonly used all around the world to identify the probability that a given level of ground motion will be exceeded within a given time span, and stands as a basic tool in many seismic design codes. One of the basic assumptions in PSHA practice that affects hazard results is the removal of foreshocks and aftershocks from earthquake catalogs to obtain independent seismic activity; however, it may cause an underestimation of the seismic hazard. This article is a new attempt to account cluster‐based PSHA for modeling of dependent‐event effects on modern seismic‐hazard analysis. The cluster‐based hazard models have commonly characterized primary aftershocks, and consequently effects of later generations have been neglected in the hazard analysis. Consideration of the multigenerational behavior of seismicity in regions following a large earthquake or cluster of large earthquakes together with their aftershock sequences can increase hazard estimations. This article proposes an analytical method to account for the effects of aftershocks in cluster‐based PSHA in which an earthquake of a given magnitude triggers its own sequence using the epidemic‐type aftershock sequence model. The hazard results indicate that incorporation of earthquake clusters into PSHA increases the seismic hazard. In addition, modeling of later generations of aftershocks leads to a higher hazard than the model allows, considering primary aftershocks, although the choice of the model describing aftershock sequences and parameters of the aftershock model highly affects the cluster‐based hazard results.
