GIS-based evaluation of seismic hazard for cultural heritage sites in Gyeongju historic areas

This study aims to evaluate the seismic hazard for cultural heritage sites based on pre-existing seismic hazard assessments, by reflecting the damage to cultural heritage sites in the Gyeongju historic area during the 2016 Gyeongju and 2017 Pohang earthquakes. Regarding site effects, the pre-existing seismic hazard assessments for cultural heritage sites suggested dependable outcomes; however, the topographic effect was considered to be negligible. The pre-existing seismic risk assessments for cultural heritage sites conducted one-dimensional equivalent linear analyses utilizing five input motions; seismic microzonation was performed by considering mountainous areas as rock outcrops with no site amplification. In this study, to assess site amplification, one-dimensional ground response analyses were carried out. Equivalent linear and non-linear analyses were conducted at thirty-six cultural heritage sites using ten input motions, including the 2016 Gyeongju and 2017 Pohang earthquakes. Their results were compared to improve the reliability of the evaluation of site amplification. Triangulation points were replaced with cultural heritage sites located in mountainous areas, and seismic microzonation was conducted based on updated information. To verify the significance of topographic effects in seismic hazard assessment, topographic features of the mountainous area were characterized by slope angle and relative elevation. Then, the possibility of topographic effects was determined by considering topographic features along with the results of ground response analyses. Complementary seismic hazard assessment shows that both site and topographic effects should be considered to estimate reliable seismic hazard.