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  • August 5, 2023
[Frontier Letter] Unified approach for evaluation of horizontal site amplification factors with special reference to history of studies on the effects of surface geology on seismic motion

Following the 1923 Kanto earthquake in Japan, Japanese researchers noticed strong effects of surface geology (ESG) on seismic motion and began to quantify the site amplification factors (SAFs) associated with soft surface sediments. Kawase et al. (2023) introduce various emerging techniques for broadband quantitative evaluations of SAFs based on the vast amount of observed ground motions primarily from dense Japanese strong-motion networks. They propose to follow five basic guidelines for the successful implementation of techniques to delineate SAFs at a target site. As seen in Fig.5, they found much smaller S-wave (horizontal) SAFs in the western side of Honshu, which is probably related to the origin of Japan Islands.