The Probability map of distributed faulting in Italy was obtained by combining information derived from two public databases: the DISS database (https://diss.ingv.it/), that is a geospatial repository that includes seismogenic sources, i.e. major active faults deemed to generate damaging earthquakes and as such used for assessing earthquake hazards, and the ITHACA database (https://sgi.isprambiente.it/ithacaweb/default.aspx#1) that collects available information on active and capable faults affecting the Italian territory, based on a critical review of the available literature.
In order to estimate the probability that a capable fault from the ITHACA database produces surface ruptures following earthquakes generated by the seismogenic sources of the DISS database, the elements of the two datasets are integrated into a system of principal and distributed faulting, a framework commonly adopted in coseismic surface faulting hazard studies. Specifically, the upper tip of the CSS seismogenic sources of DISS are treated as principal faults along which primary faulting occurs. Conversely, the capable faults from the ITHACA database are assimilated into distributed faulting phenomena that develop in association with primary faulting.
The selection of models for estimating the conditional probability of distributed faulting occurrence was guided by: (i) their compatibility with the methodological approach developed for the DISS–ITHACA interoperability; (ii) the updated status of the reference databases adopted; and (iii) the consistency of each model’s applicability range with the Italian seismotectonic setting. Consequently, for each kinematic style, the most up-to-date model best aligned with this framework was selected: for normal faults, we selected the model by Ferrario and Livio (2021), whereas for reverse and strike-slip faults, the models by Takao et al. (2014) were adopted.
Ferrario, M. F., and Livio, F. (2021). Conditional probability of distributed surface rupturing during normal‐faulting earthquakes. Solid Earth, 12(5), 1197–1209. https://doi.org/10.5194/se‐12‐1197‐2021.
Takao, M., Ueta, K., Annaka, T., Kurita, T., Nakase, H., Kyoya, T., & Kato, J. (2014). Reliability improvement of probabilistic fault displacement hazard analysis. Journal of Japan Association for Earthquake Engineering, 14(2), 2‐16–2‐36. https://doi.org/10.5610/jaee.14.2_16.
