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Multiple impacts caused by CO2 diffusely released from soils in volcanic environments

Fátima Viveiros1,2, Catarina Silva1,3

  • Affiliations:  1 Instituto de Investigação em Vulcanologia e Avaliação de Riscos (IVAR), Universidade dos Açores; Ponta Delgada, Portugal; 2 Faculdade de Ciências e Tecnologia da Universidade dos Açores, Ponta Delgada, Portugal; 3 Centro de Informação e Vigilância Sismovulcânica dos Açores, Ponta Delgada, Portugal 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 17

  • Programme No: 6.6.5

  • Theme 6 > Session 6

Abstract

CO2 diffusely released from soils in volcanic areas may affect infrastructures, environment, fauna and humans during eruptive and quiet periods of activity. A recent review of the literature highlighted lethal air CO2 concentrations (> 100 000 ppm) in different volcanic systems, such as Azores (Portugal), Canary (Spain) and Aeolian Islands, Colli Albani (Italy), Massif Central (France), Methana (Greece), Mammoth Mountain (USA), Rotorua (New Zealand), Nyamulagira and Nyiragongo (DR Congo) volcanoes. When population is exposed, reported symptoms include nausea, vomiting, dizziness, tiredness, increasing breathing rate, loss of consciousness, which are essentially associated with the reduced oxygenation. Human and animal casualties have been also reported. In the Azores archipelago, several villages are located in high soil CO2 emission zones resulting in high indoor CO2, depending also on the edifices vulnerability. Values higher than 200 000 ppm have been measured in some buildings in the last 20 years, which are mainly explained by the high CO2 emission and the effect of meteorological parameters on the gas fluxes. In anomalous thermal zones, indoor CO2 may rise to the upper floors of the buildings and reach higher concentrations than at the expected ground level. In some of the degassing areas, high indoor 222Rn and H2S concentrations highlight the multi-gas permanent hazard. These hazardous concentrations detected in quiescent and extinct volcanoes suggest that the gas is transported to the surface through extensional tectonic structures. Bared soils and altered vegetation are also some of the impacts reported in the Azorean degassing areas.