Coseismic extension recorded within the damage zone of the Vado di Ferruccio Thrust Fault, Central Apennines, Italy

摘要: Recent high resolution hypocentral localisation along active fault systems in the Central Apennines illuminates activation of seismogenic volumes dipping at low angle (<30°) extensional settings overprinting contractional deformations affecting continental crust Adria microplate. Individuation geological structures and processes associated with these seismic patterns will contribute to interpretation sequence evolution, hazard studies. Here we report field microstructural evidence faults localized within pre-existing thrust zones. The Vado di Ferruccio Thrust Fault (VFTF) is a narrow zone (<2.5 m thick core) Italy, accommodating ∼1 km shortening during Miocene-Pliocene exhumed from <3.5 km depth. In zone, exposures throughout Fornaca Tectonic Window show Late Triassic bituminous dolostones over Middle Jurassic interlayered carbonates upon SSW-dipping fault. Isoclinal folds are dragged sheared by thrust-parallel reverse footwall block whereas NW-striking occur hanging wall. core observations consistent stable pressure solution-mediated aseismic sliding towards N024° thrusting, cyclic veining faulting. Later extension has been accommodated regional scale major normal cutting through VFTF, while veins pressure-solution seams crosscut microstructures thrusting record stress regime core. Lenses shattered rocks (up 10 s m thick), cut dense network small displacement (<1.2 m) mirror-like faults, reported hangingwall VFTF. These minor related sharp principal slipping surface on upper margin VFTF core, interpreted as fossil microseismicity compartmentalized wall Synthetic antithetic damage geometrically kinematically similar earthquake ruptures (Mw < 2) such flats illuminated 2009 Mw 6.1 LAquila sequence.