Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

294 PATA Days 2024 K E Y W O R D S Paleoearthquakes, Statistical modeling, Surface rupture scenarios, Individual fault and regional seismic hazard evaluation, Apennines normal faults (1) Istituto Nazionale di Geofisica e Vulcanologia, Italy. *Email: daniela.pantosti@ingv.it Lombardi A.M. (1) Cinti F.R. (1) Pantosti D. (1) PALEOEARTHQUAKES MODELING AND EFFECTS OF UNCERTAINTIES ON PROBABILITY ASSESSMENT OF NEXT FAULT RUPTURES: THE CASE OF CENTRAL ITALY SURFACE FAULTING EARTHQUAKES A B S T R A C T Using the published paleoseismological native trenching data for 16 faults in Central Italy, we compile a new database of surface faulting earthquakes, having quite stable statistical properties since 6000 BCE. By applying a probabilistic aggregation method, we correlate the event ages from distinct trenches on each fault to construct all possible individual fault rupture scenarios, consistent with geological constraints. These fault time histories are the basis for both individual fault and regional seismic hazard evaluation. We investigate how the probability of future events varies considering all sources of uncertainty, related to both ages and rupture temporal models. We find that data and model uncertainties have a large impact on probabilities of next rupture for individual faults; they depend on basic features of the temporal model and on the relation between the elapsed time and the mean interevent time. At a regional scale, we cannot exclude the simplest possible model, i.e. the Poissonian behavior, that provides quite stable probabilities of future events, close to 27% in the next 50 years. I N T R O D U C T I O N The present study has been carried out with the main goal of characterizing the earthquake occurrences and of constructing earthquake rupture forecasts, both for individual faults and at regional scale, using paleoearthquakes dataset in the Central Apennines (Lombardi et al., 2024 submitted). In the following, we summarize the steps of the work: the set of the paleoseismological data; the procedure applied to generate rupture scenarios for each fault; the earthquake forecast assessment, for individual faults and at regional scale, made by including all uncertainties related to both ages and rupture temporal models.