A New Approach for Real-Time Erupted Volume Estimation From High-Precision Strain Detection Validated by Satellite Topographic Monitoring

Timely estimations of magma volumes emitted during an eruption or a sequence of explosive events are vital for investigating the eruptive activity and evaluating the associated hazard. A reliable method for estimating erupted volumes is based on the analysis of digital surface models that nowadays can be obtained subsequently using stereo or tri-stereo optical satellite imagery. However, the real-time estimation of the erupted volumes is still an open challenge. Here, we explore the capacity of extracting volume estimates from continuous measurements of volumetric strain changes recorded by borehole dilatometers. We compare the volumes derived from numerous high spatial resolution satellite images with high precision strain records at Etna during 2020-2022, when more than 60 lava fountains occurred. The good correlation between the two data sets shows that strain changes can be used as a proxy to estimate the emitted volumes both over time and in real-time. Quantifying erupted volumes is fundamental in volcanology to provide a robust characterization of eruptions. To date, estimates of erupted volumes have been calculated after the eruptions have ended and the real-time estimation of the erupted volumes is still an on-going challenge. In recent decades, the sequences of lava fountain-type eruptions at Etna, with dozens of episodes close in time and more than 100 episodes occurring since 2011, has made the task of estimating the volumes in real-time during each single eruption ever more essential. This would enable providing precise information to Civil Protection authorities and contribute toward hazard evaluation. In this study, we took on this new challenge by exploring the potential to extract erupted volume estimates from continuous measurements of strain changes, recorded by high-precision borehole instruments installed on the volcano's flanks. We compared and validated the volumes deriving from numerous high spatial resolution satellite images with high-precision strain records at Etna during 2020-2022, when more than 60 lava fountains occurred. The good correlation between the two data sets shows that strain changes can be used effectively as a proxy to estimate the emitted volumes, both over time and, more importantly, in real-time. Detection of strain changes during sequences of lava fountain eruptions from continuous recording high-precision borehole instrumentsQuantifying erupted volumes from strain changes, comparison and validation with the volumes calculated from high spatial resolution satellite measurementsNew method to estimate the erupted volumes in real-time by using the continuous strain recording