Relatore: Aldo Zollo, Professore Ordinario, Dipartimento Scienze Fisiche - Università degli Studi di Napoli "Federico II"
Seminario presso LGIT - Laboratoire de Geophysique Interne et Tectonophysique, Universite Joseph Fourier, Grenoble, France
Earthquake early warning systems (EEWS) are real-time monitoring infrastructures that are able to provide rapid notification of the potential damaging effects of an impending earthquake. The final aim is to predict the expected damage and losses at critical infrastructures, tens of seconds before the occurrence of the strong ground shaking produced by the earthquake. The operability and reliability of an EEWS thus depends on the fast telemetry and processing of data from dense instrument arrays deployed in the source region of the event of concern or surrounding the target site. For a regional EEWS, the relevant source parameters (event location and magnitude) are estimated from the early portion of recorded signals in the near-source region. They are used to predict, with a quantified confidence, a ground motion intensity measure at a distant site where a target structure of interest is located. Recently, robust and effective algorithms for the real time and evolutionary event location have been developed to provide in few seconds the information about the hypocenter location. On the other hand the feasibility of a real-time earthquake magnitude determination using the information carried out in the initial portion of recorded P- and S-signals is matter of investigation and debate. In this seminar we shall review the principles, methods and technological developments related to the feasibility and implementation of a regional early warning system with a special focus on the seismic alert management system under construction in Campania region, southern Italy. We shall describe a probabilistic, evolutionary approach for the real time location and magnitude estimation based on a general strategy, where the computation starts when few seconds of data from a small number of recording stations are available, and the source parameters estimates along with their uncertainties are progressively updated with time. The method testing and validation is illustrated through the analysis of and application to Euro-Mediterranean and Japanese earthquake records.