GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 NEW PALAEOSEISMOLOGICAL EVIDENCE OF COSEISMIC SURFACE RUPTURE ACROSS THE CARNIC PREALPINE FRONT (NE-ITALY): THE BUDOIA-AVIANO THRUST SYSTEM M.E. Poli 1 ; G. Patricelli 2 ; E. Falcucci 3 ; S. Gori 3 ; G. Paiero 1 ; E. Rizzo 2 ; A. Marchesini 1 ; R. Caputo 2 (1) Università di Udine, Dipartmento di Scienze Agroalimentari, Ambientali e Animali (2) Università degli Studi di Ferrara, Dipartmento di Fisica e Scienze della Terra (3) Isttuto Nazionale di Geofsica e Vulcanologia In the framework of the PRIN_2020 “Fault segmentaton and seismotectonics of actve thrust systems: the Northern Apennines and Southern Alps laboratories for new Seismic Hazard Assessments in northern Italy (NASA4SHA)”, we conducted a palaeoseismological study into the area comprised between the Budoia and Aviano localites (western Carnic Prealps, NE Italy). The investgated area, which is part of the external Plio-Quaternary front of the Eastern Southalpine Chain, is characterized by the presence of distnct WSW-ENE trending and S-verging reverse fault planes arranged in thrust systems and afectng the Quaternary succession (Poli et al., 2014). In detail, the geological and morphotectonic survey highlighted many evidence of recent deformaton afectng the Last Glacial Maximum alluvial fan of the Artugna Stream, including morphological anomalies of both the topography (scarps) and the hydrography of minor streams. Following the multdisciplinary and multscale approach, the preliminary geophysical survey, which included multscale Electric Resistvity Tomograhy (DERT and ERT) and Ground Penetratng Radar (GPR), allowed us to identfy the site for the excavaton of two palaeoseismological trenches (Rizzo et al., this session) The excavated walls intersected a set of medium-to-high angle reverse planes verging towards the North, which displace the alluvial fan stratgraphy and also afect the soil. At about 2 m depth from topography, we identfed a paleosoil dividing two alluvial fan units and afected by deformaton. The radiocarbon datng of the paleosoil sample revealed an age of about 16 ky BC. The palaeoseismological analysis allowed us to estmate a cumulatve slip, measured on all fault planes, of the order of at least 4.5 m. Moreover, we detected at least three seismic events, the most recent of which is possibly referable to the 1873 M 6.3 Alpago - Cansiglio earthquake (CPTI15, Rovida et al., 2022).