Hyblean discrete geodetic network
Hyblean discrete geodetic network (reference: Alessandro Bonforte)
Just after the December 13 1990 earthquake, the first GPS surveys were performed in 1991 in the epicentral area, across the Scordia-Lentini graben, with the aim of detecting near field deformation related with this tectonic structure. The GPS network partially included the already existing local trilateration network (surveyed by the Electromagnetic Distance Measurement technique) installed by the International Institute of Volcanology (IIV) of Catania in the same period for similar aims and the IGMI levelling route.
After 1991, the GPS network was extended and presently comprises 50 stations, including the older EDM and GPS benchmarks. The new geodetic monuments consist in iron and concrete pillars on top of which a screw allows the GPS antenna to be directly installed. This installation allows instrumentation set-up errors to be avoided. From 1998, GPS surveys are carried out on the northern part of network. The surveyed network is located between the town of Siracusa and Catania and extends from the Ionian coastline to the central Hyblean plateau. It was designed with an average grid of about 10 km to constrain both the local seismic and aseismic crustal deformations related to the present tectonic activity.
