A multi-parameter investigation of volcanic plume behavior and resultant environmental impact at a persistently degassing volcano, Masaya, Nicaragua

Recent advances in volcanic gas sensing technology make possible detailed investigations of the behavior of boundary layer gas plumes. An intensive survey of SO2 flux during two month-long campaigns revealed an apparent decrease of 30-50% downwind of Masaya volcano, Nicaragua. Dry deposition of S and aerosol conversion cannot account for such losses. Local topography modifies regional trade winds, causing plume acceleration. The resulting along-axis dilution of the plume leads to underestimates of total SO2 emissions. This apparent depletion can be accounted for by accurate determination of plume speed at the location of each SO2 flux measurement. Interaction of acidic plumes with elevated topography results in widespread vegetation damage downwind, which may be characterized by a multi-parameter approach incorporating ground-based datasets and Landsat NDVIs at Masaya and other volcanic systems. A thorough understanding of plume behavior is essential for accurate evaluation of volcanic SO2 output and resultant environmental impacts.