Attenuation Models for Estimation of Vertical Peak Ground Acceleration Based on PSO Algorithm for the North of Iran

Peak ground acceleration (PGA) is a critical parameter in ground-motion investigations, in particular in earthquake-prone areas such as Iran. In the current study, a new method based on particle swarm optimization (PSO) is developed to obtain an efficient attenuation relationship for the vertical PGA component within the northern Iranian plateau. The main purpose of this study is to propose suitable attenuation relationships for calculating the PGA for the Alborz, Tabriz and Kopet Dag faults in the vertical direction. To this aim, the available catalogs of the study area are investigated, and finally about 240 earthquake records (with a moment magnitude of 4.1 to 6.4) are chosen to develop the model. Afterward, the PSO algorithm is used to estimate model parameters, i.e., unknown coefficients of the model (attenuation relationship). Different statistical criteria showed the acceptable performance of the proposed relationships in the estimation of vertical PGA components in comparison to the previously developed relationships for the northern plateau of Iran. Developed attenuation relationships in the current study are independent of shear wave velocity. This issue is the advantage of proposed relationships for utilizing in the situations where there are not sufficient shear wave velocity data.

Keywords:
Attenuation relationships
Northern Iranian plateau
Optimization
PSO algorithm
Vertical PGA component.