Geotechnical study in Orkoien

In Orkoien, the geological substrate is composed mostly of limestones, dolomites and marbles, which together account for 67% of the exposed materials, representing a competent rock base for shallow and deep foundations, particularly when they are located in continuity and without significant alterations. However, around 27.55% of the area, fine sands and silts are also present; their density will need to be investigated to ensure adequate bearing capacity and to avoid differential settlements. The isolated presence of water masses suggests the possibility of local aquifers, although low-permeability formations predominate.

With regard to seismicity, Orkoien shows high activity, with 200 events recorded over the last 30 years and a maximum magnitude (Mmax) of 5,2, so this factor must be considered carefully in the structural design calculations for buildings. Although no predominant karstification has been identified, there is a risk of expansivity associated with the presence of non-expansive or dispersed clays within a non-clayey matrix, which means it is necessary to analyse, on a point-by-point basis, the swelling susceptibility in those areas where these facies occur. Seismicity and local variability in fine soils emerge as the priority geotechnical factors to study before founding in the municipality.