Examples of Multi-Sensor Determination of Eruptive Source Parameters of Explosive Events at Mount Etna

Multi-sensor strategies are key to the real-time determination of eruptive source parameters (ESPs) of explosive eruptions necessary to forecast accurately both tephra dispersal and deposition. To explore the capacity of these strategies in various eruptive conditions, we analyze data acquired by two Doppler radars, ground- and satellite-based infrared sensors, one infrasound array, visible video-monitoring cameras as well as data from tephra-fallout deposits associated with a weak and a strong paroxysmal event at Mount Etna (Italy). We find that the different sensors provide complementary observations that should be critically analyzed and combined to provide comprehensive estimates of ESPs. First, all measurements of plume height agree during the strong paroxysmal activity considered, whereas some discrepancies are found for the weak paroxysm due to rapid plume and cloud dilution. Second, the event duration, key to convert the total erupted mass (TEM) in the mass eruption rate (MER) and vice versa, varies depending on the sensor used, providing information on different phases of the paroxysm (i.e., unsteady lava fountaining, lava fountain-fed tephra plume, waning phase associated with plume and cloud expansion in the atmosphere). As a result, TEM and MER derived from different sensors also correspond to the different phases of the paroxysms. Finally, satellite retrievals for grain-size can be combined with radar data to provide a first approximation of total grain-size distribution (TGSD) in near real-time. Such a TGSD shows a promising agreement with the TGSD derived from the combination of satellite data and whole deposit grain-size distribution (WDGSD).

Automated summary

In this study, we analyzed data from multiple sensors during two different intensity volcanic eruptions at Mount Etna, Italy, and found that different sensors provide complementary observations that should be critically analyzed and combined for comprehensive estimates of eruptive source parameters (ESPs). The measurements of plume height during strong paroxysmal activity agreed, while discrepancies were found for weak paroxysms due to rapid plume and cloud dilution. Different sensors also provided information on different phases of the paroxysms, allowing for the conversion of total erupted mass (TEM) to mass eruption rate (MER) and vice versa. Additionally, satellite retrievals for grain-size combined with radar data showed promising agreement with total grain-size distribution (TGSD) derived from satellite data and whole deposit grain-size distribution (WDGSD).