Erlangen 2018 – scientific programme

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UP: Fachverband Umweltphysik

UP 2: Atmosphere - trace gases, Methods - remote sensing

UP 2.6: Talk

Monday, March 5, 2018, 12:15–12:30, G 1.011

BrO/SO₂ variations in the volcanic gas plumes of Cotopaxi and Tungurahua — •Florian Dinger^1,2, Nicole Bobrowski^1,2, Simon Warnach^1,2, Stefan Bredemeyer³, Silvana Hidalgo⁴, Santiago Arellano⁵, Bo Galle⁵, Ulrich Platt^1,2, and Thomas Wagner¹ — ¹MPIC, Mainz, Germany — ²IUP, Heidelberg, Germany — ³GEOMAR, Kiel, Germany — ⁴IGEPN, Quito, Ecuador — ⁵CTH, Gothenburg, Sweden

Variations of the BrO/SO₂ ratio in volcanic gas plumes have been proposed as a proxy for volcanic activities. We present and discuss BrO/SO₂ data measured via remote sensing at Tungurahua and Cotopaxi. At Tungurahua, BrO/SO₂ ratios varied from <1· 10⁻⁵ to 16· 10⁻⁵ between 2007 and 2017. Lower ratios have been predominately observed at periods when the seismic activity elevated as it has been observed at other volcanoes, such as Nevado del Ruiz and Etna. In 2015, Cotopaxi awoke from a 72-years period of relative quiescence. The BrO/SO₂ ratios in Cotopaxi’s gas plume were <1 · 10⁻⁵ from May 2015 until the week after the phreatomagmatic explosions in August 2015 and increased to a mean value of 4· 10⁻⁵ in the period from September to December 2015. This change partially correlates with the evaporation of the hydrothermal system prior to October 2015. Further, during the period from September to December 2015 the BrO/SO₂ ratios oscillated between 2 and 8 · 10⁻⁵ with a conspicuous periodic pattern of a period of 13.7 days. We found a partial correlation between BrO/SO₂ and the tide-induced surface displacement in North-South direction with a correlation coefficient of 47 %.