Geotechnical study in Larrabetzu

In Larrabetzu, the ground is characterised mainly by the presence of limestones, dolomites and marbles, which represent more than 77% of the substratum, followed in smaller proportions by sandstones, conglomerates and flysch. These rock formations provide a firm and competent base with generally high bearing capacity, which favours direct foundation solutions, particularly in areas where a good rock mass is available at shallow depth. Fine sands and silts, due to their rarity and properties, usually do not significantly influence works, although their localised presence must be identified during the geotechnical study to rule out differential settlements.

The seismicity in Larrabetzu is very low, with barely one recorded event in the last 30 years and a very low maximum magnitude, which minimises the seismic constraint in projects. The fact that the substratum is not clayey eliminates the risk of expansiveness, providing greater security both against seasonal movements and against any problems associated with unstable soils. The main factor to consider will be the localised detection of less competent strata and the checking of fracturing in limestone areas.