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- Variações sazonais na monitorização contínua do fluxo de CO2 do solo no Vulcão das Furnas (ilha de São Miguel, Açores)Publication . Pacheco, Joana; Viveiros, Fátima; Silva, Catarina; Ferreira, T.Resumo: Diversos estudos têm demonstrado que variáveis ambientais (e.g. meteorológicas) podem afetar a emissão de gases através dos solos, identificando, em alguns casos, variações sazonais na desgaseificação difusa de CO2 em regiões vulcânicas. O presente estudo pretende complementar os trabalhos realizados anteriormente no Vulcão das Furnas relacionados com a desgaseificação difusa de CO2, tendo como principal objetivo confirmar a existência de variações sazonais no fluxo deste gás. Para tal, foram analisados os dados da estação permanente de fluxo de CO2 (GFUR2) entre outubro de 2011 e março de 2015. As medições de fluxo de CO2 foram realizadas através do método da câmara de acumulação. Os dados obtidos sugerem a existência de variações sazonais, com registos de valores mais elevados durante os meses de inverno quando comparados com os meses de verão, confirmando assim a variação observada em trabalhos anteriores.
- Fumarolic gas monitoring after an hydrothermal explosion at caldeira do Asmodeu (Furnas volcano, Azores)Publication . Moreno, Lucia; Viveiros, Fátima; Silva, Catarina; Pacheco, Joana; Cojocariu, M.Abstract: On the 30th of August 2017 an explosion occurred in Caldeira do Asmodeu fumarole located in the Furnas Village fumarolic field, São Miguel Island. Local inhabitants reported that the turbidity of the water increased before the explosion and all the water disappeared immediately after the event. Subsequently, the water appeared with a muddy aspect. Sampling of the gases released from a close fumarole was done the following day and one week after the explosion. Chemical analyses included gas chromatography for the gases in the headspace of the bottles and titration for those in the alkaline solution. Results obtained were compared with data gathered since 2015 and some ratios were applied to the gas compositions of the fumaroles before and after the explosion. The results obtained did not show significant differences and contributed to confirm that the phenomena should be quite superficial, thus not related with deep changes on the system.
- Secondary manifestations of volcanism – an open window to understand geothermal resources in the Azores archipelagoPublication . Viveiros, Fátima; Silva, Catarina; Moreno, Lucia; Pacheco, Joana; Ferreira, T.Abstract: Gas geochemistry techniques applied to fumaroles and soil diffuse degassing areas constitute fundamental tools to understand deep geothermal reservoirs thermodynamic conditions and may provide valuable information both during the exploratory and production phases. Geothermometry applied to fumaroles located at Fogo (São Miguel Island) and Pico Alto (Terceira Island) volcanoes showed maximum feeding temperatures around 256 and 263 ºC, respectively, for each area, which are in general in agreement with the direct temperature measurements performed in the geothermal wells. Soil CO2 flux degassing maps performed at Caldeiras da Ribeira Grande (Fogo) and Furnas do Enxofre (Pico Alto) fumarolic fields allowed to estimate the CO2 naturally emitted to the atmosphere as well as the thermal energy released from both degassing areas. Fumaroles, diffuse degassing areas, geothermometers.