A Feasibility Study on Monitoring Crustal Structure Variations by Direct Comparison of Surface Wave Dispersion Curves from Ambient Seismic Noise

Figure 4

Example of FTAN map showing Rayleigh wave group velocity for the path ESPZ–JUBA for the spectral band corresponding to two frequency bands: (a) secondary (5–10 s) microseism band and (b) primary (10–30 s) microseism band. The yellow areas in the map are those associated with the energy arrivals. Cyan dots indicate relative maxima for a given filter central period. Blue dots indicate the period corresponding to the fundamental mode of Rayleigh waves. In this figure, we show the overall energy distribution normalized to 1, whereas the energy was normalized for each frequency to improve the tracking of group arrivals. The measured group velocity values () are plotted against the filtered central period ().

(a)

(b)