Estimating VS30 at Korean Peninsular seismic observatory stations using HVSR of event records

Abstract

The VS30 of 89 stations in Republic of Korea are predicted using semi-empirical relationship between natural frequency (fp) selected from horizontal-to-vertical spectral ratio (HVSR) and time averaged shear wave velocity down to 30 m depth (VS30). The installation of seismic stations has been accelerated in Republic of Korea after two damaging earthquakes at 2016-2017, but the majority of stations do not have geophysical investigation yet, and even for a few stations the investigation is prohibited due to deforestation issue and civil complaints. The objective of this study is to predict VS30 for stations without investigation using fp to VS30 relationship. The HVSR of 48 stations with measured VS30 are analyzed to find appropriate fp selection and the best-fitted model. We found that the fp-VS30 relationship is weak if the peak is not distinct and HVSR amplitude is low, and the model developed for the stable continent region fits the best.