Radon concentration in caves as a proxy for tectonic activity in The Cantabrian Mountains (Spain)

Radon (Rn) constitutes a good geochemical tracer for neotectonic activity in faults since associated fracturing near the surface favours fluid escape to atmosphere. In this contribution, we measured Rn concentration air inside karst caves constraints recent fault Cantabrian Mountains (N Spain). Rock formations exhumed during uplifting of record long history fracturing, which has potential connect deeper sources with surface. regional study, correlate measurements cave survey data and geological structures using Geographic Information Systems. Thirty-four average was recorded by CR-39 detectors 8 integrated months. The method is applied central part that built on sedimentary low-grade metamorphic rocks relatively poor U. Dominant tectonic are examined 28 cavities. values higher than 0.5 kBq·m-3 developed preferably following fractures direction N30oW, being greater 0.8 cavities located less 200±50 m from subvertical such orientation. anomalies point relative high connectivity along zones NW-trending, preserving fracture most Mountains. Finally, study area there low but significant radioactive hazard fractured rock massif. It contrasts other active settings where may come movements.