A Combined Velocity Field of the Mediterranean Region

We present a full 3-D velocity field of the Earth’s surface in the Euro-Mediter
ranean area obtained from a combination of three different velocity solutions
computed at the Centro Nazionale Terremoti (CNT) of the Istituto Nazionale
di Geofisica e Vulcanologia (INGV). All the publicly available GPS data since
1993, have been fully reprocessed by three different software tools and the final
velocity field is estimated combining three independent velocity solutions in a
least squares sense. The input velocity solutions are treated as stochastic sam-
ples of the true velocity field by loosening the reference frame constraints in the
associated variance-covariance matrix. The proposed approach allows for a
fast and efficient combination of multi velocity solutions, taking into account
the full network covariance, if available. The velocity map for the Euro-Medi-
terranean region will be updated and released regularly on the web portal of
the National GPS Network (http://ring.gm.ingv.it) and made available to
the scientific community. Here we show and discuss the data analysis and the
combination schemes, and the results of the combined velocity field.