(a)–(d) Average P station residuals for V_P/V_S = 1.76 for (a) the 3-D model and (b) the layered model, and for V_P/V_S = 1.90 for (c) the 3-D model and (d) the layered model. (e)– (h) Average S station residuals for V_P/V_S = 1.76 for (e) the 3-D model and (f) the layered model, and for V_P/V_S = 1.90 for (g) the 3-D model and (h) the layered model