The research in this area is aimed at developing low-cost techniques for the determination of the depth profile of elastic rigidity from surface data. In particular, the research focuses on the application of ambient vibration measurements carried out at the surface with individual stations (HVSR) or seismic antenna (ARRAY) for the dynamic characterization of the subsoil. The research covers two main aspects. The first is the physical modeling of the environmental vibration field through physical models and numerical procedures. This kind of study is a prerequisite for the development of inversion procedures suitable for the reconstruction of the characteristics of the subsoil from seismic data. Considerable advances have been made in this direction that have allowed us to overcome the limitations of the models most widely applied and to develop new and more effective inversion procedures. The most advanced research in this area relate to the in-situ determination of the dissipative properties of the subsoil materials. The second aspect concerns the determination of experimental procedures effective for a correct determination of the characteristics of the wave field of environmental vibrations. Given the practical importance of these investigations, it is essential to establish appropriate criteria for validation and qualification of measurements in order to make these techniques applicable in practice. The development of general protocols is very advanced and has been implemented in the new Guidelines for the Seismic Microzonation issued by the Conferenza dei Presidente delle Regioni e delle Province Autonome e dal Dipartimento Nazionale della Protezione Civile (Italian National Department of Civil Protection). In these studies are currently involved researchers of the University of Basilicata and Bologna, the National Department of Civil Protection and the Washington Department of Natural Resources (USA). They also implemented a number of agreements with the Regione Emilia-Romagna for testing of these techniques, in order to support the activities for the elaboration of cards seismic micro-zoning maps at municipal scale.
This research concerns some critical aspects of the process of seismic hazard asessment: the use of site-based macroseismic information, critical analysis and updating of the ground motion prediction equations in terms of macroseismic and instrumental data, and statistical study of the level of completeness of earthquake catalogs. This research has led to the development of a new procedure for the statistical/probabilistic estimate of seismic hazard at a national scale, starting from the seismic history of a number of sites, derived from the analysis of the available historical evidence. The methodology developed allows us a more accurate assessment of seismic hazard by an accurate parameterization of involved uncertainties, and also allows full exploitation of the large data base now available on the local effects of historical earthquakes. The latest developments in this area are related to the application of the above hazard estimates for the determination of the reference earthquake, to be used for the study of seismic response and other engineering applications. These studies are carried out in close coordination with the National Department of Civil Protection, the Geological Survey of the Regione Emilia-Romagna and other University Departments. Other research in this area relate to the development and implementation of strategies for the validation of seismic hazard maps from the comparison with the observed seismicity. These procedures will provide a formally correct assessment of the quality of the different hazard algorithms, in order to identify the most effective procedures. The research in these areas have previously been funded by the National Department of Civil Protection and the National Institute of Geophysics and Volcanology.
We operate a network of 10 permanent GPS stations located in Tuscany. Moreover, the data collected from more than 300 permanent GPS stations in the central and northern Italy are analyzed. The results obtained are used for the determination of the horizontal velocity and strain rate fields and the pattern of vertical ground motion. The possible implications of such pieces of information for the assessment of seismic hazard are then considered. This investigation is being conducted under an agreement between the Dipartimento di Fisica, Scienze della terra e dell’Ambiente and the Regione Toscana, aimed at the assessment of seismic hazard and the definition of priority criteria among the Tuscan seismic zones, to be used for optimal management of the resources allocated for seismic prevention.
Through the analysis of a vast amount of pieces of evidence, a very detailed reconstruction of the seismotectonic framework of the Italian region is carried out. This knowledge, supplemented by the study of the propagation of stress and strain perturbations induced by strong seismic events, is used to interpret the spatio-temporal distribution of historical earthquakes in Italy. The information provided by this research may have significant implications for the estimation of deterministic seismic hazard in Italy. This research has been carried out with the financial support granted by the Regione Toscana, the Italian Space Agency (within the SIGRIS Project) and the Italian Ministry of University and Research (1997, 1999, 2001, 2003, 2005 and 2007).
This research investigates the role of the stress and strain perturbations induced in the crust by strong earthquakes generated at major peri-Adriatic seismic sources. The research (supported by the Regione Toscana, the Italian Space Agency and the Italian Ministry of University and Research), makes use of elastic-viscous finite element modelling of the crust-mantle system to properly take into account the structural, thermal and rheological properties of the study area. The results obtained by numerical experiments are compared with the information on the seismic history and space geodesy (GPS) measurements, to understand how the post-seismic perturbations may influence the activation of the major Italian seismic sources.
- Babbucci Daniele (Fellow)
- Tamburelli Caterina (Fellow)
- Paolucci Enrico (PhD student)