Geotechnical study in Balmaseda

In Balmaseda, the terrain is predominantly formed by sandstones, conglomerates and flysch, accompanied in smaller proportions by limestones, dolomites and marbles. These lithologies impart characteristics of high strength and low deformability to the ground, which generally translates into good bearing-capacity conditions for shallow foundations. Owing to their low or negligible permeability, these formations usually limit the presence of deep aquifers, although localised shallow aquifers associated with specific fractures could exist, an aspect to consider especially in projects that require deep excavations or pumping.

Seismic activity in Balmaseda is very low—just 3 events in 30 years with a low maximum magnitude (Mmax 2)—which implies a seismic hazard level that is practically negligible for construction. In addition, since the bedrock lacks expansive clayey facies, the risk of problems related to expansivity is categorically ruled out. Accordingly, the main geotechnical considerations in Balmaseda will be determined by the local characterisation of the rock substratum and the identification of possible altered zones or shallow aquifers associated with fracturing.