Self-potential anomalies in some Italian volcanic areas

The study of self-potential (SP) space and time variations in volcanic areas may provide useful information on both the geometrical structure of the volcanic apparata and the dynamical behaviour of the feeding and uprising systems. In this paper, the results obtained in the islands of Vulcano (Eolian arc) and Ponza (Pontine achipelago) and on the Mt.Somma-Vesuvio complex are shown. In the island of Vulcano and on the Mt. Somma-Vesuvio apparatus areal SP surveys have been performed with the aim of evidencing anomalies closely associable to the zones of major volcanic activity. In the island of Vulcano also a profile across the fumaroles along the crater rim of the Fossa Cone has been carried out in order to have a direct relationship between fumarolic fracture migration and flow rate and SP anomaly space and time variations.The areal survey in the island of Ponza, which is considered an inactive area, is assumed as a reference test with which to compare the amplitude and pattern of the anomalies in the active areas. A tentative interpretation of the SP anomalies in volcanic areas is suggested in terms of electrokinetic phenomena, related to the movement of fluids of both volcanic and non-volcanic origin.