A new dense CGPS network in Southern Italy to study plate boundary deformation

Abstract

The collision between Africa and Eurasia is associated with a complex pattern of deformation within the plate boundary zone, with subduction of oceanic fragments, crustal extension along formerly contracting orogenic belts and back-arc spreading in Tertiary basins. First-order scientific problems regarding the strain accumulation along seismogenic structures, the present-day activity of the Calabrian slab, the existence of rigid blocks within the plate boundary and the regional crust and upper mantle structures are still awaiting for a better understanding. To solve those open questions, the CESIS project, established in 2002 by the INGV (Istituto Nazionale di Geofisica e Vulcanologia), is deploying 60 permanent CGPS stations in Southern Italy. All the sites will be equipped with Leica GRX 1200 Pro GPS receivers acquiring at 1Hz sampling interval for seismic source analysis. The data are then transmitted at 30s sampling interval by means of a satellite system (VSAT) to two acquisition centres, located in Rome and in Irpinia. Furthermore, the network sites are integrated either with broad band and very broad band seismometers or accelerometers to improve the monitoring of the background seismicity in Southern Appennines seismic belts and to better constrain the geometry of the seismogenic structures. The satellite data transmission and the integration with seismic instruments makes this network one of the most innovative CGPS networks in Europe. New developments on the GPS monumentation have also been carried out. The research activity resulting from the data coming from the CESIS network will thus exploit the full range of temporal and spatial frequencies that characterize plate boundary deformation, allowing a large range of scientific problems, ranging from earthquake source studies to regional plate kinematics, to be tackled. Some of the most intriguing targets concern (a) the study of present activity of the Calabrian slab and its associated crustal deformation, (b) the southern boundary of the Adriatic block (a rigid microplate whose existence have been proposed on the basis of seismicity distribution, earthquake slip-vectors, and space geodesy), (c) the study of strain build-up along seismogenic faults and (d) the processes which allow the deformation to be localised or distributed on the fault systems. We present (a) a new prototype of short-drilled braced GPS monumentation, (b) the technical description of geodetic data acquisition, (c) the flow and archiving of geodetic data, and (e) the first results of data analysis