1. Department of Basic and Applied Sciences for Engineering (SBAI), University of Rome La Sapienza, Via Antonio Scarpa 14, 00161 Rome, Italy
2. National Institute of Geophysics and Volcanology (INGV)—The Etna Observatory, Piazza Roma 2, 95125 Catania, Italy
3. Research Microscopy Solutions (RMS), Carl Zeiss S.p.A., Via Varesina 162, 20156 Milan, Italy