Etn@ref: a geodetic reference frame for Mt. Etna GPS networks

In volcanology, geodetic data are one of the most important instruments for the scientific community interested in modeling physical processes related to magma movements in the shallow crust. Since the end of the 1980s, GPS surveys and continuous GPS stations have greatly improved the possibility of measuring such movements with high time and space resolution. However, physical modeling requires that any external influence on the data that is not directly related to the investigated quantity must be filtered. One major tricky factor in determining a deformation field using GPS displacement vectors and velocities is the correct choice of a stable reference frame. In this study, we defined a local reference frame using more than a decade of GPS measurements, to refer the Mt. Etna ground deformation pattern to a rigid block. In particular, we used a weighted least-squares inversion to estimate the Euler pole for the rigid block by minimizing the adjustments to two horizontal components of GPS velocity at 13 << fiducial >> sites located within a 350-km radius of Mt. Etna. The inversion inferred a Euler pole located at 38.450 degrees N and - 107.702 degrees E, and a rotation rate of 0.263 deg/Myr.