oa Electric Resistivity Tomography in 2D and 3D Applied to Characterize Urban Subsoils

More than 70% of urban areas seated on the Basin of Mexico were built on what was once Lake of Texcoco, which is mainly made up of clayey sediments. The growth of Mexico City and surrounding areas has increased the supply of drinking water to the inhabitants of this region. Over time, this process of exploitation of the aquifers has caused a differential subsidence in the valley, reaching in some points (towards the N and NE) up to 40 cm/year. If we add to this, the increase in water-extraction wells, leaks in pipe lines, etc., the hydrostatic balance in the subsoil has been modified, which has seriously affected the buildings and houses settled on these clays. This paper presents the effects on urban areas and how geophysical methods, particularly the Electrical Resistivity Tomography method in its 2D and 3D modalities, can characterize the subsoil, in such a way that geological and anthropogenic features that may represent a risk for urban infrastructure on the surface can be recognized. Some examples are presented where the Exploration Group has worked on: location of cavities, detection of fracture patterns, subsidence, among others.