Figure 7
Spectral and spatial signal analyses of the subsidence signal over the calibration area. (a) Results of implementing the SWAB algorithm on the power spectrum’s radial profiles. The blue dots present the averaged power spectrum of six individual profiles and the red line represents a best-fit two-term exponential model. Black lines are two best-fit linear curves and red dot marks the location of a \({D}_{1}\) threshold (0.0021 cycles/m) (See Fig. S2). (b) Selected velocity transects across Metro line 4 showing apparent uplift. Each curve is calculated from averaging and detrending 20 3 m-spaced transects. The peak in each curve corresponds to apparent uplift produced by the Metro system. Spatial wavelengths are measured between the local minima closest to the Metro line (red dots).
