Preprints
https://doi.org/10.5194/nhess-2022-60
https://doi.org/10.5194/nhess-2022-60
 
01 Mar 2022
01 Mar 2022
Status: a revised version of this preprint is currently under review for the journal NHESS.

Updated area-source seismogenic model for seismic hazard of Italy

Francesco Visini1, Carlo Meletti1, Andrea Rovida2, Vera D'Amico1, Bruno Pace3, and Silvia Pondrelli4 Francesco Visini et al.
  • 1Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy
  • 2Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Milano, Milano, Italy
  • 3Dipartimento di Ingegneria e Geologia, Università degli Studi di Chieti-Pescara, Chieti, Italy
  • 4Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Bologna, Italy

Abstract. A new probabilistic seismic hazard model, called MPS19, has been recently proposed for the Italian territory, as a result of the efforts of a large national scientific community. This model is based on 11 groups of earthquake rupture forecast inputs and, particularly, on 5 area-source seismogenic models, including the so-called “MA4” model. Data-driven procedures were followed in MA4 to evaluate seismogenic parameters of each area source, such as upper and lower seismogenic depth, hypocentral depth distributions and nodal planes. In a few cases, expert judgment or ad-hoc assumptions were necessary due to the scarcity of data. MA4 consists of 20 seismicity models that consider epistemic uncertainty in the estimations of the completeness periods of the earthquake catalogue, of maximum magnitude values and of seismicity rates. In particular, 5 approaches were adopted to calculate the rates, in the form of truncated Gutenberg-Richter frequency-magnitude distribution. The first approach estimated seismicity rates using earthquakes located in each source zone, while the other approaches firstly calculated the a and b values of the truncated Gutenberg-Richter relation for groups of zones considered tectonically homogeneous, and successively partitioned in different ways the a values to the zones forming each group.

The results obtained in terms of seismic hazard estimates highlighted that the uncertainty explored by the 20 seismicity models of MA4 is at least of the same order of magnitude of the uncertainty due to alternative ground motion models.

Francesco Visini et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2022-60', Anonymous Referee #1, 05 Apr 2022
    • AC1: 'Reply on RC1', Francesco Visini, 16 May 2022
  • RC2: 'Comment on nhess-2022-60', Julian Garcia-Mayordomo, 06 Apr 2022
    • AC2: 'Reply on RC2', Francesco Visini, 16 May 2022
  • RC3: 'Comment on nhess-2022-60', Anonymous Referee #3, 08 Apr 2022
    • AC3: 'Reply on RC3', Francesco Visini, 16 May 2022

Francesco Visini et al.

Francesco Visini et al.

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Short summary
As new data are collected, seismic hazard models can be updated and improved. In the framework of a project aimed to update the Italian national seismic hazard model, we proposed a model based on definition and parametrization of area sources. Using geological data, seismicity and other geophysical constraints, we delineated three-dimensional boundaries and activity rates of a seismotectonic zoning, and explored the epistemic uncertainty by means of a logic tree approach.
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