Characterizing the subsurface structure and active faults of the Fucino Basin (Central Apennines) through integrated high-resolution seismic reflection and nodal ambient noise surveys

The Fucino Basin, the largest tectonic basin within the Central Apennines orogen, is bounded by normal faults that have controlled the deposition of over 1 km of Pliocene-Quaternary continental deposits above a Messinian substratum. Conflicting interpretations from legacy seismic profiles have hindered a full understanding of the basin’s stratigraphy, age, evolution, and fault systems, creating uncertainties for tectonic reconstructions, seismic response analysis and hazard assessment. To resolve these uncertainties, we acquired new high-resolution datasets through three complementary active–passive seismic surveys. These include seismic reflection profiles covering ∼10 km, a nodal ambient noise campaign deploying 258 short-period nodes over 16 km 2 , preceded by two pilot array tests, and finally a basin-wide ambient noise survey comprising 1-hour recordings at 42 sites. Our analysis focused on the San Benedetto and Trasacco Faults—responsible for the 1915, M7.1, Marsica earthquake—and the main depocenter (the Bacinetto) associated with the San Benedetto Fault. This paper presents experimental setup, recorded data, and initial findings that provide new insights into basin stratigraphy, fault geometry, and spatial distribution of the fundamental resonance frequency (f 0 ). The seismic reflection data show excellent imaging quality, resolution, and penetration exceeding 1 km. The Bacinetto hosts up to 850–900 m of continuous lacustrine succession and lower fluvio-lacustrine deposits that record sustained syn-sedimentary slip along the San Benedetto Fault from the Late Pliocene to Recent times. No evidence is found for significant synthetic or antithetic faulting beneath the depocenter, contradicting earlier structural models. The intra-basin Trasacco Fault forms a clear basement step and localized sediment thickening that tapers northwestward f 0 varies from 1 to 2 Hz near the basin margins to ∼0.2 Hz in the Bacinetto, reflecting progressive sediment thickening, whereas it varies abruptly across fault zones. f 0 estimates from nodal and station data show good consistency.