High Precision Tilt Observation at Mt. Etna Volcano, Italy

Abstract

In 2007-2008, we installed on Mt. Etna two deep tilt stations using high resolution, self-leveling instruments. These installations are a result of accurate instrument tests, site selection, drilling and sensor positioning that has allowed detecting variations related to the principal diurnal and semidiurnal tides for first time on Mt. Etna using tilt data. We analyzed the tidal effects recorded on tilt signals and we removed tidal effects from signals, thereby allowing to detect changes of about 20 nrad with a considerable improvement in respect to the previous installation. Tilt changes have accompanied the Mt. Etna main eruptive phases and are generally related to the rapid rise of magma and formation of dikes and eruptive fissures. However, tilt changes may characterize lava fountains, earthquakes, and inflation-deflation phases. The 2008-2009 eruption represents an example of the potential of the tiltmeters we used, which provides new perspectives for highly precise monitoring of ground deformation on volcanoes.