Geotechnical study in Legazpi

In Legazpi, the predominant geological substrate is composed of limestones, dolomites and marbles, also presenting sandstones, conglomerates and flysch in a secondary manner. Carbonate formations are usually compact and not very deformable, which allows relatively efficient direct foundations, although with low permeability and, in some cases, the presence of shallow aquifers. However, it is essential to assess the continuity and quality of the rock, since small inclusions can vary the local bearing capacity, particularly where more detrital intercalations occur.

Seismic activity in the municipality is very low, with only 5 events in 30 years and a maximum magnitude of 1.9, so it does not represent a relevant constraint for structural design. Nevertheless, the existence of karst phenomena associated with limestones and dolomites requires carrying out a detailed karst verification before undertaking any foundation, as underground cavities may exist that could affect the safety of the works. The non-clayey substrate rules out the risk of expansivity, with the main geotechnical challenge being the correct identification of potentially karstic structures.