Areal-source and fault-source based probabilistic seismic hazard analysis using characteristic earthquake model and Monte-Carlo approach: An example of the Gulf of Aqaba region

Here, we describe a technique for probabilistic seismic hazard assessment based on a combination of a characteristic earthquake model and an areal seismic source model. One of the active regions in the Middle East, the Gulf of Aqaba, was used as an example. Five active faults located inside the Gulf of Aqaba (GA), representing the southern part of the Dead Sea Transform fault system, were included in the characteristic earthquake model. The hazard estimations were obtained using the Monte Carlo approach, consisting of the generation of a set of synthetic earthquake catalogs and the calculation of ground motion from all earthquakes in all catalogs. It is assumed that the large earthquakes with magnitudes M > 6.5 may happen on the GA active fault system, while earthquakes with magnitudes M ≤ 6.5 are distributed inside the areal GA zone. This technique considers individual as well as combined faults. The stochastic catalogs generated using the characteristic earthquake model showed conformity with the recurrence of large (M > 6.5) historical earthquakes that have occurred in the studied region over the last 1000 years. The seismic hazard maps obtained using the characteristic earthquake model clearly reflected the location and influence of the considered faults. It seems that the areal source model, in which a single zone is used for the entire Gulf of Aqaba, does not adequately describe seismic hazard. For practical applications, we suggest calculating the hazard from separate faults and their combinations and then constructing the final seismic hazard map using a weighted average scheme.