Sylvía Rakel Guðjónsdóttir flytur fyrirlestur um verkefni sitt til meistaraprófs í jarðfræði. Verkefnið ber heitið Gas emissions from the Krýsuvík high-temperature geothermal system, Iceland.
Ágrip
A high-temperature geothermal field is located within the Krýsuvík volcanic system on the Reykjanes Peninsula. Since 2009 episodes of uplift followed by subsidence periods have been observed in the area by continuous GPS measurements and InSAR. In April 2013, near-real time monitoring of gas emissions was initiated in Krýsuvik using a MultiGAS sensor system which collects a semi-continuous time series of gas composition. This monitoring method is relatively new in Iceland, with the first station installed on Hekla volcano in 2012. This study is the first to provide a critical evaluation on the suitability of the MultiGAS method in Iceland. Gas emissions in Krýsuvik are examined and correlated with other geophysical and metrological data. The gas emission dataset comprises semi-continuous MultiGAS time series, diffuse CO2 gas flux from three areas, direct samples from fumaroles of dry gas and condensates, seismic and GPS records. The MultiGAS dataset and fumarole samples indicate that the gas emissions are H2O dominated, with CO2 the most abundant dry gas species. The semi-continuous MultiGAS dataset reveals higher variations of gas composition than previously reported by spot sampling. The diffuse CO2 soil flux from Krýsuvík was estimated 101.4 T/day. Correlating MultiGAS data with geophysical data suggest that peaks of H2O/X ratios (X = CO2, H2S) follow events of crustal movements. SO2 was also detected in minor amounts (~0.6 ppmv) at the same time, the first time it has been detected in the Krýsuvík area. The high variations in H2O/X ratios are interpreted to be related to the intensity of degassing activity in the fumarole. The intensity of the fumarole is thought to be lower during intervals of low or no recorded seismic events. The H2O/X ratios measured with the MultiGAS station are consequently lower due to condensation processes affecting the H2O concentration before the steam reaches the inlet tube 20 cm above ground level.
Leiðbeinendur: Evgenia Ilyinskaya, Sigrún Hreinsdóttir og Þráinn Friðriksson
Prófdómari: Halldór Ármannsson