Conclusions

In theory, combining the fundamental mode with the first higher mode results in $V_s$ and $V_p$ profiles better defined over the whole soil column. The influence of the first higher mode in the inversion is probably more complex than the conclusions of Xia et al. (2003). In our tests, the first higher mode alone better constrains the velocity of the intermediate layer and the depth of the basement than the fundamental mode even defined on a very wide frequency range. However, the velocity of the half space basement is better retrieved with the fundamental mode.

In a real case, the limited range of the available dispersion curves ruins all positive aspects of the inclusion of the first higher mode. Redundancy of both curves (above 5 Hz in this case) just allows a cross-check of the results found with the fundamental curve alone.