1. Progetto S5 – Test sites per il monitoraggio multidisciplinare di dettaglio WP2.4 – Ground deformation pattern of the Calabro-Peloritan area and the Messina Strait from GPS networks and terrestrial data Mattia M. 1, Aloisi M. 1, Anzidei M. 2, Bruno V. 1, Cannavò F. 1, Cheloni D. 2, DAgostino N. 2, Mastrolembo B. 3, Palano M. 1, Serpelloni E. 2 INGV - Sezione di Catania 2) INGV - Centro Nazionale Terremoti, Roma 3) Dipartimento di Fisica, Università di Bologna

2. GOALS Velocity and strain rate field across the Messina Straits and the Calabrian Arc from the analysis of periodical and continuous GPS data. Elastic block modelling, inter-seismic strain loading and deep geometry of the 1908 Messina fault. Analysis of triangulation data for the estimates of the strain rates in the Messina Straits and the interseismic tectonic loading on the fault responsible for the 1908 Messina earthquake. Modelling of the source responsible for the December 28, 1908 earthquake, by using a numerical approach (i.e. finite element).

3. Reference Frame: EURASIA Observation Time 1996.00 – 2008.21 GPS velocity GPS strain-rate Strain-rate computed as described in Haines and Holt, 1993. Mattia et al., 2009, Tectonophysics

4. Ground deformation modeling GPS velocity field was modeled by using 3 different approaches: 1)vectorial decomposition of velocities measured across main fault system. 2)analytical inversion of residual velocity field computed taking into account the motion of the African plate with respect to the Eurasian plate. 3)analytical inversion of velocity field taking into account the GPS baselines and their length variations.

5. GPS velocities (with 95% error ellipses) in a Eurasia- fixed reference frame. We use only stations with > 2.5 yrs time-span. ~30° ~4.5 mm/yr ~3 mm/yr ~6.5 mm/yr KAl TGF Eurasia fixed ApEu 4.0 mm/yr NuEu 4.9 mm/yr

6. We use rectangular, uniform-slip, dislocations embedded in an elastic, homogeneous and isotropic half-space and a constrained, non-linear optimization algorithm, to solve for the best fit rectangular fault geometry and fault slip rate. Assuming a quasi 2D model, we constrain the fault strike, base on the estimated strain-rate field, and explore all other parameters. Uncertainties (68% confidence level) have been estimated using a bootstrap approach. 7.6 km 30° 3.5 mm/yr 1.6 mm/yr

7. Shear strain rates (nanostrain/yr) and Orientation of the most extensional strain (degrees) 1 2 1 2 -23.37-113.8848.7154.96140.7944.89 Shear strain rates plottati come gamma totale nella direzione di massima estensione. Daniele Cheloni, Tesi Dottorato Univ. Bologna

8. Ground deformation modeling of leveling data (Loperfido, 1909)

9. Sensitivity test

11. CONCLUSIONS The main objectives of the WP have been achieved. The FEM modelling of the source responsible for the December 28, 1908 earthquake is still in progress. Thank you!