The 2016 Italian seismic hazard model

Abstract

The Italian reference seismic hazard model was released in 2004, but it has been adopted for the definition of seismic zones in 2006 and for building code only in 2009. At the beginning of 2015 the Seismic Hazard Center (CPS) of INGV was commissioned to coordinate the national scientific community with the aim of elaborating a new reference seismic hazard model, mainly finalized to the update of seismic code. The CPS designed a roadmap to release within 2 years a significantly renewed model, with regard both to the updated input elements and to the strategies to follow, in order to obtain a shared and largely accepted PSHA. The main requirements of the model were discussed in meetings with the experts on earthquake engineering. A public call was opened according to a transparent procedure; we received 24 proposals from many national institutions. The activities were organized in 6 tasks: project coordination, input data, seismicity models, ground motion prediction equations, computation and rendering, validation. In the first phase, the working groups of each task worked separately; in the second phase of the project they collaborated to release a final model. During the project, many scientific aspects were carefully considered, as in many other seismic hazard projects: the use of a declustered catalogue versus a non declustered one, the adoption of the logic-tree approach instead of an ensemble modeling, the definition of objective strategies to assign the weight to each single model, and so on.