- Ground-motion model is:
_{0}to c_{4}, h and σ are from Joyner and Boore (1981) and c_{6}and V_{0}are not significant at 90% level so do not report them. - Use data of Joyner and Boore (1981).
- Continuous site classification for soil sites in terms of shear-wave velocity, V , to depth of one quarter wavelength of waves of period of concern. V measured down to depths of at least 30m and then extrapolated using geological data. V known for 33 stations.
- Soil amplification factor based on energy conservation along ray tubes, which is a body wave argument and may not hold for long periods for which surface waves could be important. Does not predict resonance effects.
- Regress residuals, R
_{ij}, w.r.t. motion predicted for rock sites on log R_{ij}= P_{i}+ c_{6}V_{j}, where j corresponds to jth station and i to ith earthquake. Decouples site effects variation from earthquake-to-earthquake variation. Find unique intercept by requiring average site effect term calculated using shear-wave velocity to be same as that calculated using rock/soil classification. - No significant, at 90%, correlation between residuals and V for PGA.
- Repeat regression on residuals using V and depth to underlying rock (defined as either shear-wave velocity > 750m∕s or > 1500m∕s). Find no correlation.