Geotechnical study in Vilagarcía de Arousa

In Vilagarcía de Arousa, soils formed by sandstones, conglomerates and flysch materials predominate, which represents a robust and stable geological base in most of the municipality. Areas with fine sands and silts, although common, have a lower bearing capacity and require special attention in building projects, as they could be affected by compaction or differential settlement. Levels of slate and schist are scarce and their overall influence is limited. The predominantly impermeable nature of the formations limits deep infiltration, but associated shallow aquifers may exist; this is an aspect to take into account when assessing groundwater level and drainage in geotechnical studies.

Seismic activity in Vilagarcía de Arousa is moderate, with 47 recorded events over 30 years, but with low maximum magnitudes (Mmax 2.9), which reduces the importance of seismic action in normal structural design. The geotechnical analysis should not be concerned about soil expansivity, since the subsoil is not clayey and, therefore, the risk of significant volumetric movements associated with changes in moisture is ruled out. No karst processes are identified in the area, so the main geotechnical constraint lies in local variability in compaction conditions and the presence of shallow aquifers.