Comparison of Fourier Amplitude Spectra of Strong Ground Motions from Taiwan and California Region

Comparison of Fourier Amplitude Spectra of Strong Ground Motions from Taiwan and California Region

The ground motion prediction equation (GMPE) is widely used around the world. Development of a local GMPE can help to predict possible future earthquakes of specific magnitudes and distance ranges, but in many regions the historical earthquake database will have some gaps (lack of data with specific magnitude ranges). In this case, databases from foreign regions might help to decide the trend of the regression feature of the extrapolated part, but regional differences should be considered carefully, owing to different seismological structures and geological settings. In this study, spectral differences of the Fourier amplitude spectra of strong ground motions are first compared for Taiwan and the California region. For these two regions, there have been a sufficient number of shallow crustal earthquake events to thoroughly consider spectral differences for similar magnitudes, hypocenter distances, site classifications, etc. The preliminary results show significant differences between the low-frequency and high-frequency bands that mainly relate to the seismogenic depth of the source and the site effect. The highlighted features of regional differences can help generate an adjustment factor for foreign GMPEs and extend the available source-scaling relationships for future possible large earthquakes.