Geotechnical study in La Alberca de Záncara

In La Alberca de Záncara, the dominant substrate is composed almost exclusively of gypsum, anhydrite and salts, characterising the area by extensive but low-permeability formations in depth, which may allow the existence of aquifers at deeper levels. These materials present a significant risk of dissolution, so any project that requires foundation work must consider the potential instability associated with collapse or subsidence. Additionally, although expansive clays exist, their occurrence is secondary or limited to specific climatic zones, generally reducing the dominant expansive risk, but not ruling it out completely in localised sectors.

As regards seismicity, the municipality records moderate seismic activity with 40 events in the last 30 years and a maximum magnitude of 4.1, so the possible seismic effect should be considered in structural design, albeit with restrictions specific to the local context. The possible presence of karst makes it necessary to carry out detailed checks before any foundation work, given the risk of cavities and natural subsidence associated with these soluble materials. In conclusion, the most relevant constraint for the feasibility and safety of foundations in La Alberca de Záncara lies in the interaction between the gypsum-bearing substrate, the susceptibility to karst-related phenomena, and the risk of salt dissolution.