Geotechnical study in Zalla

In Zalla, soils comprising sandstones, conglomerates and flysch predominate, representing more than half of the municipality’s formations. These substrates, together with the significant presence of limestones, dolomites and marbles, provide a generally competent foundation for construction, with good bearing capacity in most cases. However, the low frequency of fine sands and silts implies a reduced risk of soft or compressible soils, although it is important to rule out their presence locally in the specific areas under study.

With notable seismicity (94 events over 30 years) and a maximum recorded magnitude of 3.7, geotechnical studies in Zalla need to assess, at minimum, the dynamic response of the ground, even though there are no major associated structural requirements linked to seismic risk. The absence of karst risk and the lack of clayey substrates rule out issues of expansivity and cavities, resulting in the main conditioning factor of the studies focusing on the correct identification of the near-surface layers and hydrogeological analysis where shallow aquifers or areas of low permeability are present.