RICERCA ITALIANA     

Blending geophysics, space techniques, geochemistry and petrology for a reference geodynamical model of the Italian region

Università degli Studi di Milano

Abstract

The present project integrates geophysical, geodetic, petrological, geochemical methodologies and space techniques in order to comprehend and to model the geodynamical processes of the lithosphere-asthenosphere system in the central Mediterranean and in the closest part of Eurasia. These processes leave their signatures on a broad spectrum of time scales, from the active deformation one, comparable to the life time of human beings, to the long time scale one, ruling the main phases of the geological history. The complexity of the structure and of the composition of the investigated domain and of its time evolution, require the proposed multidisciplinary approach to unravel their key features. Petrology and geochemistry will constrain geophysical data, such as the seismological and the heat-flow ones, allowing us the mapping of the lithosphere in 4-dimensions, space plus time. Geochemically distinct types of Plio-Quaternary igneous rocks will be studied, their regional distribution, high-pressure mantle xenoliths entrained in volcanic rocks, the nature and location of the important boundaries (crust-mantle and lithosphere-asthenosphere boundaries), depth and lateral extent of magma sources, and the compositional variations in the lithospheric mantle through time, constituting our 4-D approach. Within this multiscale point of view, finite element models will be implemented, in order to better exploit the models cross-checked by geophysics, geochemistry and petrology. The >>>

Principal Investigator

Roberto SABADINI Università degli Studi di MILANO

Research Objectives

The general objective of the present project, based on the synergic use of geophysical and space technique methodologies with petrological and geochemical ones, is to constrain the structure of the Earth and to model the geodynamic processes affecting peninsular Italy and surrounding regions, that leave their signatures on a broad spectrum of time scales: from the short one of present-day active deformation, responsible for the seismicity in Italy, to the long time scale one, ruling the main phases of the geological history. The complexity of the region under investigation is expressed by the strong heterogeneities of the crust-mantle system and the wide variety of Plio-Quaternary magmatic rocks and is the result of the geodynamic evolution, which affected the Mediterranean during the Neogene and Quaternary times. The generated mosaic of compositionally and structurally distinct mantle domains, that have undergone different evolutionary histories in terms of compositional and structural modifications, requires a multidisciplinary approach to unravel its key features. The implementation of the forward geophysical models targeted towards the imaging of the geometries of the deep structures obtained from seismic tomography, joint with gravimetry, the simulation of active tectonics, and the comprehension of the geodynamical processes affecting the Italian peninsula and surrounding regions greatly benefit and require a strong input from petrological and geochemical data. Thus we >>>

First Results

UNIMI
1) Implementation of the effects of the faults within the finite elements numerical models (thin-sheet) developed by the UR;
2) Implementation of dip-slip and strike-slip seismic sources within the analytical models at high spatial resolution for the modelling of co-seismic and post-seismic deformation, for a compressible crust;
3) Implementation of the methodology for the integration (data fusion) of GPS and SAR data;
4) Installation of permanent GPS receivers;
5) Implementation of automatic procedures for the acquisition, control and storage of the data for the permanent GPS receivers;
6) Contribution to the analysis of the data from the permanent GPS receivers managed by CGS-ASI and from those managed directly by the research units of the University and Politecnico of Milan.
POLIMI
1) At the end of the first year research, the design of the permanent GPS network at national scale will be fixed and the non-standard analysis of the time series of the sites belonging to the network will be accomplished.
2) The geodetic deformation pattern in the whole Italian area will be estimated in a more reliable way. This deformation pattern will be compared with the results coming from the geodynamical modelling defined by the other RUs of the project to validate the structural models over Italy and surrounding areas.
3) The non-permanent network GPS data will be processed using standard scientific >>>

Timescale

24 months

National and international background

The proposed project has both national and international bases. The team from Milan has already obtained original results, published in the international literature, on the importance of lithospheric and mantle layering on the evaluation of post-seismic deformation following large earthquakes (C.N.R. project no. 96.00354.00354) (Sabadini and Vermeersen, 1997). In order to correctly estimate the effects of post-seismic deformation in seismogenetic regions, it is necessary in fact to account for rigidity and density discontinuities in the upper and lower crust. The stratification of the upper mantle plays an important role on post-seismic deformation at large distances from the fault. These results are relevant for the present project, the objectives of which are the modelling of the geodynamics of large areas of peninsular Italy and the monitoring of surface deformation in seismogenetic regions. This new class of stratified, viscoelastic Earth models has allowed to obtain the first estimate of post-seismic deformation rates for shallow, normal faulting and moderate size earthquakes, as those that striked the Umbria-Marche in 1997 (Riva, Aoudia, Vermeersen, Sabadini and Panza, 2000). This work is the result of the integrated approach and strong cooperation between the UR of Trieste and Milano, both University and Politecnico, during the project COFIN1998 supported by the Italian Ministry of the University and Research (M.U.R.S.T.). This reserch is carried on within the >>>