Delineation of potential seismic sources using weighted K means cluster analysis and particle swarm optimization (PSO)

Potential seismic sources play an important role in seismic hazard analysis. Identification of seismic sources is generally carried out on the basis of expert judgments, and in most cases, different and controversial results are obtained when several experts are consulted. In fact, the method of source identification is probably an important cause of uncertainty in the seismic hazard analysis. The main objective of this research is to provide an algorithm which combines the weighted K-means clustering analysis and Particle Swarm Optimization in order to automatically identify global optimum clusters by analysing seismic event data. These clusters, together with seismotectonic information, can be used to determine seismic sources. Two validity indexes, Davies–Bouldin's measure and Chou–Su–Lai's measure (CS), are used to determine optimum number of clusters. Study area is located at the longitude of 46°–48° E and latitude of 34°–36° N that is considered as the most seismically active part of Zagros continental collision zone, which has experienced large and destructive earthquakes due to movements of Sahneh and Nahavand segments of Zagros Main Recent Fault. As a result, 7-cluster model which is identified on the basis of DB validity index seems to be suitable for the considered earthquake catalogue, despite some limitations in partitioning.