1. Department of Earth Sciences; University of Florence; Via G. La Pira 4,; I-50121; Florence; Italy
2. Institute of Geosciences and Earth Resources; CNR; Via G. La Pira 4,; I-50121; Florence; Italy
3. Environmental and Earth Sciences Department; University of Rochester; 227 Hutchison Hall,; Rochester; New York; 14627; USA
4. Department of Environmental Sciences; Second University of Naples; Via Vivaldi 43,; I-81100; Caserta; Italy
5. Goma Volcano Observatory; Mount Goma,; Goma; Democratic Republic of the Congo
6. Estacion Experimental de Zaidin; Prof. Albareda 1,; E-18008; Granada; Spain