Quantitative Modeling of Volcanic SO2: Integrated Monitoring of Precursory Activity

Abstract:

Many volcanoes produce some level of precursory activity prior to a large eruption. However, this activity may only be detected depending on the available monitoring system in place. In certain cases, precursors can be interpreted to make forecasts about the timing and magnitude of the impending eruption. Furthermore, changes in this activity are used to determine the style of the eruption provided the mechanics producing these precursory signals are properly understood. One important precursory measurement is the rate of volcanic gas exsolution. In particular CO₂ and SO₂ are measured to predict changes in the magma depth as well as its composition. Another important precursory measurement is the thermal flux discharged from summit vents. For example, three precursory periods at Kliuchevskoi volcano in 2005, 2007, and 2009 were studied using thermal infrared (TIR) satellite data obtained from both the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Advanced Very High Resolution Radiometer (AVHRR) sensors. TIR data is also sensitive to the spectral absorbance of volcanogenic SO₂. Software to detect and model SO₂ flux has now been applied to previously-acquired ASTER data of these three eruptions at Kliuchevskoi. By directly comparing the measured thermal flux and the modelled SO₂ flux during the precursory period, the mechanisms leading to the larger eruption are better resolved. Applying these same techniques to future precursory activity would allow the type and duration until onset of the impending eruption to be better predicted in the precursory phase.