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Rayleigh waves

Rayleigh wave anomalies
a) Observed phase velocity map for Rayleigh waves at 167 s (Laske and Masters, 1996). The phase velocity perturbation typically varies between -1.5% and 1.5%.
b) After the correction for crustal signal, these variations are substantially larger.
c) Observed phase velocity map for Rayleigh waves at 40 s (Ekstrom et al., 1993).
d) Map corrected for crustal signal. The crust correction at this period does not increase the variance but redistributes the anomalies.