A backbone probabilistic seismic hazard analysis for the North Tehran Fault scenario: Fid-Bau Portal

A backbone probabilistic seismic hazard analysis for the North Tehran Fault scenario

Kowsari, Milad / Ghasemi, Saeid

Abstract In this study, a comprehensive probabilistic seismic hazard analysis (PSHA) using both time-independent and time-dependent approaches is carried out for the North Tehran fault (NTF) scenario. We applied a novel backbone approach to consider the epistemic uncertainty associated with the ground motion estimates. For this purpose, a backbone ground motion model (GMM) is selected using the data-driven deviance information criterion (DIC) method, and the logic tree branches are populated with the backbone GMMs that are added/subtracted from a scale factor. The results show that the estimated ground motions follow the spatial pattern of the NTF and decrease in the far-field, but this spatial pattern is also influenced by the amplification from site effects, in the southern alluvium part where the sites are classified as the category D of NEHRP. Furthermore, the effect of the multi-segment rupture is investigated using a cascading model. The results show that the ground motion values are increased by 20–40% and 10–20% for the 10%-in-50 years and 2%-in-50 years, respectively, particularly at near-fault distances. The results of this study are generally compatible with the previous seismic hazard studies for the Tehran region. Therefore, the novel backbone approach used in this study provides a more reliable seismic hazard estimates for the Tehran metropolis.

Highlights • In this study, a probabilistic seismic hazard analysis (PSHA) is carried out for the North Tehran fault (NTF) scenario using both time-independent and time-dependent approaches. • Moreover, the effect of the multi-segment rupture is investigated using a cascading model. • The epistemic uncertainty associated with ground motion estimates is addressed by a novel backbone approach. • The results show that the backbone approach of this study provides a more robust estimation of the GMM-contribution to the epistemic uncertainty leading to more reliable seismic hazard estimates for the Tehran metropolis.