Fig. 19

Estimated values of unknown parameters for equilateral and most-flattened triangles using the observed data. The legend is the same as that in Fig. 9. The phase velocities, \(X_1\) and \(Y_1\), are determined well, and the estimated values for \(X_2\) and \(Y_2\) depend on the initial data set and are not stable. The solid black lines show theoretical dispersion curves for the fundamental mode of Rayleigh waves propagating in a ground with the velocity structure shown in Table 3