Speaker
Description
We use infrasound waves generated by volcanic eruptions at Volcan Tungurahua to study both changing atmospheric conditions and source characteristics. Analyzed infrasound data were recorded for a 32 month period at Volcan Tungurahua by a five-station network (within 6.5 km from the vent). We use cross-network correlation to quantify the cyclic eruptive behavior of Tungurahua and results are corroborated by reports from the Ecuadorian monitoring agency. Cross-network correlation lag times are used to compute ~6.75 m resolution infrasound source positions, which take into account coarse NOAA atmospheric models for local winds and temperatures. Variable infrasound-derived source locations suggest source migration during the 32 months of analyzed data. Such source position variability is expected following energetic eruptions that destructively altered the crater/vent morphology as confirmed by imagery obtained during regular overflights. We also observe variations in cross-network lag times over short time periods (seconds to days) when vent location is stable and attribute these variations to changes in atmospheric structure. Assuming a fixed source location we invert for average air temperatures and winds in Tungurahua's vicinity (<6.5 km) and find evidence for diurnal and semidurnal tropospheric tides.
