A comparison of approaches for the prediction and inversion of surface wave phase delays

Abstract

50 s and that finite-frequency theory is superior for Love waves at periods >125 s. The € winner' approach indicated that exact ray theory is superior at short periods, whereas finite-frequency theory is superior at long periods. However, when only the great-circle ray and finite-frequency approaches were considered, we found that each approach was superior as often as it was not. We solved for phase velocity maps with the measurements using two inversion approaches: the great-circle ray approximation and finite-frequency theory. While output maps generated using both approaches were generally similar, analysis of the variance reduction and the correlation with the input map showed that the great-circle ray theory inversion yielded phase velocity maps that better explained the measurements and matched the input maps. On the basis of the tests we have performed and the results we have obtained, we recommend using great-circle ray theory instead of 2-D finite-frequency theory for the analysis of surface wave phase delays, at least on the global scale.