Fig. 2

a, b Plots of observed PGAs (larger of two horizontal components) and PGVs (larger of two horizontal components) after adjustment for site amplification, respectively. Only a subset of data shown in Fig. 1a were plotted where the values of Vs30 were known or estimated. The solid lines represent median prediction curves using equations in Si and Midorikawa (1999, 2000) for Mw = 6.6, depth = 37, and type of event = crust, and dashed lines denote plus–minus one standard deviation. In the legends, BA, FA, and NLA are the abbreviations for back-arc, fore-arc, and nonlinear site response analyzed sites. c, d Plots of residuals for the PGAs and PGVs plotted in a, b, respectively. Mean residuals with a plus–minus one standard deviation are shown by vertical bars for four different distance ranges 20–50 km, 50–100 km, 100–200 km, and 200–300 km