GNGTS 2021 - Atti del 39° Convegno Nazionale

191 GNGTS 2021 S essione 2.1 Traces along with the observations made that lead to determination of the trace location scale and trace activity scale, are presented at the scale that primary observations are made so there is transparency for the modeller and end-user regarding which observations have led to the location and activity scale designation. (2) Faults represent how the traces are connected at the surface and/or at depth.  (3) Main Faults, the inferred structures that guide the design of seismogenic sources. The main faults map represents surface interpretations of fault connections at depth between faults, based on continuation of surface geometry, total offsets profiles, surface slip vectors convergence, and consideration of rupturing during contemporary, historical and paleo earthquakes. Third, the Fault2SHA CAD includes primary slip-rate data, i.e. direct measurements from the field with the locations and methods used for inferring both the displacement and time periods over which the slip-rates are calculated together with uncertainties in these and reference to the papers where the data were originally published. The point locations for the slip-rates allow modellers to infer slip-rate profiles along a fault and uncertainties in these. The time periods and reference to methodologies allow the end- users to see what methods and assumptions have been made in inferring slip-rates and hence hazard and risk modellers can show the path between primary data and slip-rate inputs in the modelling. The data can be extracted for use in fault-based hazard assessments, in particular the modeller has access to the primary data so has the potential to include detailed uncertainty analyses. The modeller can decide which level of mapping (main faults, faults, traces) to incorporate within their hazard model. At the main fault level, we have provided some alternate options where there are different interpretations of how to connect faults. The modeller will need to decide how they allow earthquakes to rupture, for example whether multi-fault ruptures are possible and if so, what are the rules governing such ruptures. Depending on model capability, the modeller will have to determine how to extrapolate slip-rate measurements along the main fault or and/or fault. How the data is used may be dependent on the scale of the model being created – for example whether local surface rupture and high precision are required or if it is a lower resolution hazard map, and whether the model is aiming to provide information on annual probabilities or investigating a worst credible event. To aid readers use the data with fault-based SHA codes, for example with the SHERIFS (Chartier et al., 2019) and FiSH (Pace et al., 2016) codes, in Faure Walker et al. (2021) we provided tools for extracting the data into the appropriate formats. The database structure can be used as a template for data reporting within the central Apennines and with possible adaptations for other regions. We suggest that data from field investigations should be reported such that the data are useful for and can be easily included into SHA calculations both within the capabilities of current models and in the future. In a companion paper (Scotti et al., 2021a) and presentation (Scotti et al., 2021b) we propose a methodology for calculating fault-based seismic hazard using the presented database, that allows for the inclusion of detailed locations of active faults and multiple measures of slip-rate along a fault and a visualisation of the results.  References Chartier T, Scotti O, Lyon‐Caen H.; 2019: SHERIFS: Open‐Source Code for Computing Earthquake Rates in Fault Systems and Constructing Hazard Models . Seismol. Res. Lett. 90(4):1678–1688. Faure Walker JP., Visini F., Roberts GP. et al.; 2019: Variable Fault Geometry Suggests Detailed Fault-Slip-Ra- te Profiles and Geometries Are Needed for Fault-Based Probabilistic Seismic Hazard Assessment (PSHA) . Bull. Seismol. Soc. Am. 109(1):110–123. doi: 10.1785/0120180137. FaureWalker J, Boncio P., Pace B., Roberts G., Benedetti L., ScottiO., Visini F. and Peruzza L.; 2020: Fault2SHA Central Apennines Database . Institute for Risk and Disaster Reduction, University College London, PAN- GAEA, https://doi.org/10.1594/PANGAEA.922582.