EGU General Assembly 2020
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Spatial-temporal variations of surface diffuse CO2 degassing at El Hierro volcano, Canary Islands

Pedro A. Hernández1,2,3, Christopher A. Skeldon4, Jingwei Zhang5, Fátima Rodríguez1, Cecilia Amonte1, María Asensio-Ramos1, Gladys V. Melián1,2,3, Eleazar Padrón1,2,3, and Nemesio M. Pérez1,2,3
Pedro A. Hernández et al.
  • 1Instituto Volcanológico de Canarias (INVOLCAN), 38240 La Laguna, Tenerife, Canary Islands, Spain (
  • 2Instituto Tecnológico y de Energías Renovables (ITER), 38611 Granadilla de Abona, Tenerife, Canary Islands, Spain
  • 3Agencia Insular de la Energía de Tenerife (AIET), 38611 Granadilla de Abona, Tenerife, Canary Islands, Spain
  • 4Hamilton College, Major BA, Geosciences, 198 College Hill Road, Clinton, NY 13323 USA
  • 5Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, U.K.

El Hierro (278 km2), the youngest, smallest and westernmost island of the Canarian archipelago, is a 5-km-high edifice constructed by rapid constructive and destructive processes in ~1.12 Ma, with a truncated trihedral shape and three convergent ridges of volcanic cones. It experienced a submarine eruption from 12 October, 2011 to 5 March 2012, off its southern coast that was the first one to be monitored from the beginning in the Canary Islands. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies are a useful geochemical tool to monitor the volcanic activity in this volcanic island. Diffuse CO2 emission surveys have been performed at El Hierro Island since 1998 in a yearly basis, with much higher frequency during the period 2011-2012. At each survey, about 600 sampling sites are selected to obtain a homogeneous distribution. Measurements of soil CO2 efflux are performed in situ following the accumulation chamber method. During pre-eruptive and eruptive periods, the diffuse CO2 emission released by the whole island experienced significant increases before the onset of the submarine eruption and the most energetic seismic events of the volcanic-seismic unrest (Melián et al., 2014. J. Geophys. Res. Solid Earth, 119, 6976–6991). The most recent diffuse CO2 efflux survey was carried out in July 2019. Values ranged from non-detectable to 28.9 g m−2 d−1. Statistical-graphical analysis of the data shows two different geochemical populations; Background (B) and Peak (P) represented by 97.5% and 0.5% of the total data, respectively, with geometric means of 1.2 and 23.6 g m−2 d−1, respectively. Most of the area showed B values while the P values were mainly observed at the interception center of the three convergent ridges and the north-east of the island. To estimate the diffuse CO2 emission for the 2019 survey, we ran about 100 sGs simulations. The estimated 2019 diffuse CO2 output released to atmosphere by El Hierro was 214 ± 10 t d-1, value lower than the background average of CO2 emission estimated on 412 t d-1 and slightly higher than the background range of 181 t d-1 (−1σ) and 930 t d-1 (+1σ) estimated at El Hierro volcano during the quiescence period 1998-2010 (Melián et al., 2014, JGR). Monitoring the diffuse CO2 emission has proven to be a very effective tool to detect early warning signals of volcanic unrest at El Hierro.

How to cite: Hernández, P. A., Skeldon, C. A., Zhang, J., Rodríguez, F., Amonte, C., Asensio-Ramos, M., Melián, G. V., Padrón, E., and Pérez, N. M.: Spatial-temporal variations of surface diffuse CO2 degassing at El Hierro volcano, Canary Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11805,, 2020.