Figure 3

Examples of localized subsidence. (a) Velocity profile along the ABC transect shown in Fig. 1f. Blue arrows and labels indicate approximate wavelengths of key subsiding features. (b) Velocity profile along the Metropolitan Cathedral’s southern façade (location in Figs. 1f, 2a). The observed velocities (black dots) are fitted by a curve (black line) with a spatial wavelength of 350 m and amplitude of 20 mm/year as shown by the blue arrows. (c) Cross-section of the main hydro-geological units along the ABC transect (modified from²⁶). (d) Schematic section of shallow sediment layers beneath Mexico City’s Metropolitan Cathedral (shown with vertical exaggeration, modified from²⁸). Interestingly, the Metropolitan Cathedral’s foundation piles (vertical black lines) reach the so-called “hard layer”. (e) Detailed view of the intermediate-wavelength subsidence component (location in Fig. 2b). The velocities indicate apparent uplift (blue colour) along the elevated viaducts of Metro lines 4 and B, a sewage canal, a shallow tunnel part of the Metro system. Apparent uplift also observed in a cluster of four large buildings: the square is the former Palacio de Lecumberri prison, the rectangle is the Chamber of Deputies, the circle is a large bus station, and the triangle is the Justice Palace. (f) Oblique Google Earth image of the Pantitlán Metro station (location in Fig. 2b) and its pedestrian overpass system. The arrows mark apparent uplift/subsidence velocities from the intermediate-wavelength component. Matlab R2015b (https://www.mathworks.com/), ArcMap 10.2 (https://www.esri.com/software/arcgis) and Google Earth Pro 7.3 (https://www.google.com/intl/en/earth/) were used to generate the figures. ArcMap 10.2 was used to produce the shaded relief map from SRTM data (https://earthexplorer.usgs.gov). Satellite imagery credits: INEGI and Maxar Technologies.