The hydrothermal system of Cerro Machín volcano (Colombia): New magmatic signals observed during 2011–2013

Cerro Machín volcano in Colombia recently (2009–2013) exhibited new seismic activity. A geochemical characterization of emitted fluids was carried out based on the chemical and isotopic compositions of fumaroles and thermal springs discharged in this volcanic area with the aim of improving the volcano monitoring program.

The isotopic composition of fumaroles located in the upper part of the dome was characterized by depleted δD and δ18O relative to the meteoric recharge fluids, which is due to a separation of the liquid phase in the lower part of the dome. A clear magmatic He signature was found in the fumaroles, with an increased magmatic contribution observed in the discharged fluids during 2011–2013 corroborating the increase in recorded seismic activity. Coupling the geochemical and seismic information has highlighted a clear awakening of Cerro Machín volcanic activity, indicating that this volcano is still active deserve an improvement of volcanic monitoring activity by the scientific community.