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Abstract Quantifying erupted masses of magma is fundamental to determine the size of eruptions. Pre- and post- eruptive Digital Elevation Models (DEMs) derived from satellite data can quantify erupted masses, even in remote areas. Here we used bistatic Synthetic Aperture Radar (SAR) data from the TanDEM-X satellite and EarthDEMs derived by stereo-optical data, to investigate topographic changes and the erupted mass at the caldera of Raung (Indonesia), which is one of the most frequently erupting volcanoes on Java. We found that erupted masses associated with Magnitude ≤ 2 eruptions occurred from 2000 to mid-2014 are difficult to be estimated with these DEMs, due to the difficultly to separate the signal of the limited amount of ash deposited within the caldera from data errors. On the contrary, these DEMs mapped at high resolution deposits of Magnitude ≥ 3 eruptions. The November 2014 – August 2015 eruption produced 11.72 ± 1.58 x1010 kg of magma (Magnitude 4.06 ± 0.06), generating lava flows with a maximum height of ~ 46–50 meters and a new intra-caldera cone. The January-April 2021 eruption, never studied before, erupted at least 2.29 ± 0.76 x1010 kg of magma (Magnitude 3.34 ± 0.15), generating lava flows (maximum thickness ~ 16–21 meters) and the growth of the intra-caldera cone. Our analysis reveals that the different pre-eruptive DEMs used to process SAR data and calculate topographic and volume changes can affect extrusive mass estimates by up to ~ 60%. Erupted masses at Raung here estimated could be used in future studies to develop physics-based models coupling extrusion rates with other monitoring parameters to further improve the knowledge of this frequently erupting volcano.
Galetto et al. (Fri,) studied this question.