Geodetic deformations in the Central-Southern Apennines (Italy) from repeated GPS surveys

Abstract

We computed the horizontal strain rate field for a sector of tbc Central-Southern Apennines (Italy) from GPS data collected during yearly repeated campaigns performed from 1994 to 2000 on tbc GeoModAp (Geodynamic Modeling of the Apennines) geodetic network. Site velocities were obtained starting from tbc daily coordinates and covariance solutions, using a Kalman filter approach. The residual velocity field with respect to a Eurasian 6xed reference frame shows two different prevalent motion trends, NE-ward for tbc eastern sector of the network and NW-ward for tbc western one. The mean strain rate tensor, obtained from a least square inversion method, shows a signifcant extensional deformation (1.2 x 10 ' strain/yr) normal to tbc Apennine chain, in agreement with seismological and neotectonic data. On the basis of tbc network dimension, of about 250 km, this value gives a well constrained estimate of about 3.0 ± 0.2 mm/yr of the extensional velocity oriented N55E, normal to the chain axis. Our results show a transition of the strain rate field from about N-S compression in tbc Tyrrbenian sfide to about NE-SW extension toward tbc Adriatic, which depicts a more complex deformation pattern.