Spatial Variation of Peak Ground Acceleration Attenuation in the Korean Peninsula

Probabilistic Seismic Hazard Analysis (PHSA) is widely used in seismic hazard assessment. The level of peak ground acceleration (PGA) is calculated based on seismicity for certain recurrence periods in PHSA. The PGA is directly related to seismic damages, and accurate estimation of probabilistic PGA is crucial for seismic hazard analysis. Thus, construction of correct PGA attenuation model is highly needed. In an 1-D PGA attenuation model, the PGA is assumed to be attenuated isotropically with distance. The PGA is, however, affected not only by the distance and source properties including magnitude, focal depth, and faulting geometry, but also by medium properties in receiver sites and raypaths. The lateral variation of PGA in the Korean Peninsula is investigated based on seismic records in dense seismic networks. To isolate the spatial variation of attenuation features, the influences of source properties are corrected by using the ratio of PGA at different distances. We present the correlations between the PGA attenuation model with known geological and geophysical properties in the crust.