Abstract
An attenuation model incorporating the dependence of attenuation slope on earthquake focal depth for 5 % damped acceleration response spectra was determined by two-step regression analysis. The relations between source effects and earthquake types were investigated. Earthquakes were classified into four types (Type A-1: shallow inter-plate earthquakes, Type A-2: shallow intra-plate earthquakes, Type B: intermediate-depth earthquakes, and Type C: inland crustal earthquakes). Variation in source effects according to earthquake types is large in shorter-period rang and incorporated into the attenuation model.
