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.Mattia M.11, Aloisi M., Aloisi M.11, Anzidei M., Anzidei M.22, Bruno V., Bruno V.11, , Cannavò F.Cannavò F.11, Cheloni D., Cheloni D.22, D’Agostino N., D’Agostino N.22, ,

Mastrolembo B.Mastrolembo B.33, , Palano M.Palano M.11, Serpelloni E., Serpelloni E.22

INGV - Sezione di CataniaINGV - Sezione di Catania

2) INGV - Centro Nazionale Terremoti, Roma2) INGV - Centro Nazionale Terremoti, Roma

3) Dipartimento di Fisica, Università di Bologna3) Dipartimento di Fisica, Università di Bologna

GOALSGOALS

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).

Reference Frame: Reference Frame: EURASIAEURASIA

Observation TimeObservation Time

1996.00 – 2008.211996.00 – 2008.21

GPS velocityGPS velocityGPS strain-rateGPS strain-rate

Strain-rate computed as Strain-rate computed as described in described in Haines and Haines and

Holt, 1993.Holt, 1993.

Mattia et al., 2009, Mattia et al., 2009, TectonophysicsTectonophysics

Ground deformation modelingGround deformation modeling

GPS velocity field was modeled by using 3 GPS velocity field was modeled by using 3 different approaches:different approaches:

1)1) vectorial decomposition of velocities vectorial decomposition of velocities measured across main fault system.measured across main fault system.

2)2) analytical inversion of residual velocity analytical inversion of residual velocity field computed taking into account the field computed taking into account the

motion of the African plate with respect to motion of the African plate with respect to the Eurasian plate.the Eurasian plate.

3)3) analytical inversion of velocity field taking analytical inversion of velocity field taking into account the GPS baselines and their into account the GPS baselines and their

length variations.length variations.

GPS velocities (with 95% error ellipses) in a Eurasia-fixed reference frame. We use only stations with > 2.5 yrs time-span.

GPS velocities (with 95% error ellipses) in a Eurasia-fixed reference frame. We use only stations with > 2.5 yrs time-span.

~30°~30°

~4.5 mm/yr~4.5 mm/yr

~3 mm/yr~3 mm/yr~6.5 mm/yr~6.5 mm/yr

KAlKAl

TG

FT

GF

Eurasia fixedEurasia fixed

ApΩEu4.0 mm/yr

NuΩEu4.9 mm/yr

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.

Uncertainties (68% confidence level) have been estimated using a bootstrap approach.

7.6 km7.6 km

30°30°

3.5 mm/yr3.5 mm/yr

1.6 mm/yr1.6 mm/yr

Shear strain rates (nanostrain/yr) and Orientation of the most extensional strain (degrees)

1 2 1 2

-23.37 -113.88 48.71 54.96 140.79 44.89

Shear strain rates plottati come gamma totale nella direzione di massima estensione.

Daniele Cheloni, Tesi Dottorato Univ. Bologna

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

Sensitivity testSensitivity test

CONCLUSIONSCONCLUSIONS

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!Thank you!