TEMA DI RICERCA:  

TITOLO DEL PROGETTO: Progettazione e installazione di un array sismico a piccola scala come sistema di “allarme sismico”

DURATA DEL PROGETTO: 12 mesi

Obiettivi

The necessary, but not necessarily sufficient prerequisite for the design of any seismic alarm system in a tectonically active area is the precise knowledge of its seismicity (detection and localization of seismic events). The main tool for reaching this objective is the lowering of the monitoring threshold by some orders of magnitude, that can be realised best with seismic arrays. In this context it must be clearly evidenced, that we don't claim, that the information provided by the proposed seismic array itself would be able to predict any earthquake. However, the monitoring capabilities of such an array provide important information, which can be used as a first step of the design of a future alarm system.

One of the main doubts expressed in the scientific commission's project valuation is the question, whether the proposed array analysis techniques can be applied successfully to earthquakes in Central Italy. The presence of strong attenuation and scattering, due to the heterogeneous geological situation in Italy, are the main reasons for those doubts.

 The detection at array stations is governed by the gain that can be achieved in the signal-to-noise ratio (SNR) through the process of beamforming. For any array geometry it is thus possible to predict the gain if the signal and noise cross-correlations are known for all pairs of sensors.

Following the referees' suggestions, that the main objective of the approved feasibility study should be a test with real field data, it is planned to collect new seismic data during a survey at one of the possible future array sites. For this purpose a mobile test array, consisting of at least 6 seismic stations will be deployed in order to determine the signal and noise cross- correlations for all pairs of sensors of the array layout.

Depending on the local and regional seismicity a recording period of 2Dž weeks should be hopefully sufficient to record a reasonable number of representative arrivals. The expected result of the data analysis will be the knowledge about the gain improvement achieved by a small scale array deployed in Central Italy and the resulting minimal magnitude threshold level.

The approved grants will be mainly used to cover the travel expenses of the field personnel.

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