Signal processing of tilt data for ground deformation modeling in volcanic areas

The problem of filtering tilt signals recorded in active volcanic areas is considered. The drawbacks of using traditional digital-filtering techniques for this kind of data are outlined, and a model-based procedure is proposed. The model-based procedure is based on three possible classes of models for the estimation of thermal effects on tilt data. The validity of this approach has been tested by using data recorded by an array operating on Mt. Etna (Italy). About 8 months before an eruption occurred, the tilt component clearly started to rise, coming out from the confidence interval delimited by two horizontal rows.