Probabilistic Seismic Hazard and Deaggregation Analysis of Guilan Region, South of Caspian Sea, Iran

This paper presents a probabilistic seismic hazard assessment (PSHA) for Guilan Province, an influential, highly populated and strategic district to the south of the Caspian Sea in northern Iran. In this study, the peak ground acceleration (PGA) and spectral acceleration (SA) over bedrock are estimated for the whole area of the province. NGA-West2 and the EMME project attenuation relationships are applied and combined using the logic tree method. Seismic hazard assessment is then carried out to establish the maps of seismic hazard distribution based on PGA values for two hazard levels as suggested by the Iranian seismic code of practice. Finally, deaggregation analysis is performed to determine the magnitude and distance pair that most prominently contributes to the seismic hazard for each district, which is of great importance for the region, as this has not been done before. Comparing the results with those suggested by the Iranian seismic code of practice and those obtained by previous studies, a general agreement seems to exist, although some violations are observed for some areas, especially in the southeastern part of the province, highlighting a need for revision of the Iranian seismic code of practice.

Automated summary

This study conducted a probabilistic seismic hazard assessment for Guilan Province in Iran, estimating peak ground acceleration and spectral acceleration over bedrock for the entire province. The results were compared with Iranian seismic code of practice and previous studies, highlighting the need for revisions in some areas.