Strain rate field from geodetic velocity measurements: an approach based on numerical modelling

The reconstruction of the strain rate field from geodetic velocity data is often carried out by geometrical procedures, such as subdivision in polygons of the geodetic network or interpolation of the velocity vectors. However, as discussed in this work, this kind of approach presents several shortcomings, which may affect the reliability of the computed strain rate field. In particular, the results of such approaches may be strongly biased by the fact that the mechanical properties of the crust in the zone considered are neglected. This problem may be overcome by the use of numerical modelling imposing the geodetic velocity vectors as kinematic constraints. As an example, the proposed procedure is applied to the Central Mediterranean region to determine the strain rate field associated with a recent geodetic (GPS) velocity data set available in literature. The comparison of the result so obtained with the one derived by polygon subdivision shows that numerical modelling allows a more detailed and reliable recognition of the strain-rate field in the zones involved.