Geotechnical study in Tona

In the municipality of Tona, white or soft expansive clays predominate as the main substrate, occurring in 87.5%, whereas sandstones, conglomerates and flysch appear sporadically. These formations generally have low permeability, which limits drainage and may favour the presence of shallow aquifers in localised areas. In terms of bearing capacity and foundations, the predominance of soft clayey materials requires special attention due to their low strength and high compressibility, directly influencing the choice of deep foundations or ground-improvement solutions on many occasions.

Seismicity in Tona is very low, with only 5 events in the last 30 years and a maximum magnitude of 1.6, so the seismic influence on structural design is practically negligible. It is important to highlight the existence of possible karst phenomena; this condition requires prior verification of the absence of voids or underground instabilities before any foundation is executed. Although the report indicates that the substrate is not predominantly clayey, which rules out the risk of expansivity, the main factor to consider in any geotechnical study in Tona will be the possible presence of karst and the low bearing capacity of the soft clays.