A shaded relief magnetic anomaly map of total intensity of the Earth's magnetic field for Italy and the surrounding seas has been produced at sea level, for the geomagnetic epoch 1979.0 (see Chiappini et al., 2000). Magnetic observations were made on shore within the framework of Progetto Finalizzato Geodinamica of the Consiglio Nazionale delle Ricerche (PFG-CNR) between 1977 and 1981. The off shore data were taken during the period 1965-1972 by the Osservatorio Geofisico Sperimentale (OGS). This new compilation gives an unprecedented view of the magnetic anomaly field of the whole area at ground level, which contains many imprints of the major tectonic elements of Italy, and portrays their regional characterization. In 2004 Caratori et al. have undertaken a detailed reprocessing of old aeromagnetic data taken by AGIP at the national scale, with the inclusion of new data. For the first time now the ground level map and the aeromagnetic map show the existence of common features that allow comprehensive correct scientific investigations.
PUN/US II. 20, 1998 Research unit: TR IESTE (Geophysics) STRUCTURE AND PHYSICAL PROPERTI ES OF THE TECTOSPHERE IN TH E METASTABLE EU ROPE Sciemiflc responsible: GIULIANO FRANCESCO PANZA Dipanimcnto di Scicnze ddla Terra. Uni' crsita di Tricstc, P.k Europa I. 1-34127 rricste c-mail: panaif<1 univ.1riestc.it Researchers: P. Suhadolc, A. Sarao, R. Cazzaro, F. Vaccari, G. Costa, F. Romanelli, S. Kravania, R. Nicolich, L. Cernobori, F. Accaino, I. Marson, I. Velicogna, B. Della Vedova, G. Pellis Funding: 1996 Lit. 25,000,000; 1997 Lit. 25,000,000 INTRODUCTION The Earth's structure and the geod) nam ic processes that originate it are strictly interconnected: an accurate knowledge of the Earth·s structure and its physical properties is fundamental for the understanding of the dynamics of our planet and critical for realistic simulations of seismic ground motion. On the other side the separation and the definition of the different dynamic processes acting in a certain area help to better understand the structure and the physical properties of the investigated region. In recent years much emphasis has been given to the inversion or observed phase and waveform data for the best fitting set or model parameters at a variety of scale-lengths. RESULTS The first step to beller understand and define 1he structural model and the phys ica l properties of the tectosphere in Europe has been the compilation a 3-D regionalized digital model of the European Crust and mantle velocity clown to depths of approximately 400 km [I]. This data set is intended to be used as a reference for seismological studies and also as a constraint to study the physical properties of the Earth. The model represents the European area from 25° W to 35° E, and from 30° N to 70° N. It is entirely based upon the existing geological and geophysical literature and it incorporates topographic and bathymetric features. The resulting model (denominated I-data set) is defined by 6400 vertical structures at nodes ith an average separation of about I 00 km. The I-data set has been compared quantitatively with some of the recent models obtained from body and surface wave tomography and it is found that the S-wave velocity in the I-data set and in the EUR-S9 I differs b) no more than about 4% in most of the area. In addition to some purely theoretical developments (2), we started to validate the I-data set by means of a 3-D gravity model using a three dimensional interactive modelling in which the effect on gravity, of homogeneous
Gravity gradiometric data or gravity data transformed into vertical gradient can be efficiently processed in three dimensions for delineating density discontinuities. Model studies, performed with the combined use of maxima of analytic signal and of horizontal gradient and the Euler deconvolution techniques on the gravity field and its vertical gradient, demonstrate the superiority of the latter in locating density contrasts. Particularly in the case of interfering anomalies, where the use of gravity alone fails, the gravity gradient is able to provide useful information with satisfactory accuracy.
The fifth in the series of International Comparisons of Absolute Gravimeters (ICAG) was held at the Bureau International des Poids et Measures (BIPM) in November 1997. Fifteen absolute gravimeters participated in the comparison. The mean gravity value obtained at station A (0.9 m) at the BIPM was found to be 980 925 707.8 µGal with a standard uncertainty of 2.8 µGal. This is consistent with the results obtained in previous comparisons at this site. Conclusions based on the analysis of the present results and proposals for future activities are presented.
