Inferences From Repeated Airborne Magnetic Measurements On The Island Of Vulcano (Eolian Islands, Italy) For Volcanic Risk Mitigation

The Island of Vulcano belongs to the active Eolian volcanic arc. Recent events on Stromboli<br>have renewed public interest and consciousness about this type of natural hazard not only in Italy, but<br>almost in the whole of Europe. A strong need for a reliable method to recognise significant changes in<br>the internal state of a volcano has risen, because of the currently ongoing and permanently changing<br>activity of the Eolian volcanic system. The measurement of variations in the local total magnetic field<br>anomaly within repeated airborne surveys is a promising strategy since rocks loose their magnetisation<br>when they are heated to temperatures higher than the so-called Curie-point resulting in a decline within<br>anomalies in the local magnetic field. Thus, changes in the geomagnetic field can indicate changes in the<br>dynamical behaviour of the geothermal volcanic system. Two airborne magnetic surveys have been<br>conducted by the Geological Survey of Austria in 1999 and in 2002 in the area of Vulcano and over a<br>part of Lipari. The raw data have to be carefully processed in order to be comparable, since they have<br>been assembled at different altitudes. Sophisticated innovative field transformation algorithms had to be<br>developed, and the rough topography and high susceptibility of the island of Vulcano require a<br>topographic correction of the measured data. Preliminary results, however, exhibit some significant<br>changes in the magnetic anomaly field.