Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior

The central Apennines are a fold-thrust belt currently affected by post-orogenic extensional seismicity. To constrain the influence that inherited thrust-related structures exert on present seismic behavior of belt, we provide high-resolution structural and hydraulic characterization one most external exposed thrust fault systems Apennines, Sibillini Mts. Thrust Front (STF). We integrate mapping, multiscale analysis, in situ air permeability brittle facies zone. also performed K-Ar dating selected rocks to better inheritance. STF is defined complex, ∼300-m-thick deformation zone involving Meso-Cenozoic marl limestone results from accommodation both aseismic slip during shortening. Permeability measurements indicate low (10−2 ÷ 10−3 D) marly rich host rock diminishes within zone, where principal surfaces associated S-C represent efficient barriers (permeability down ∼3 × 10−10 sub-vertical fluid flow. Field data began its evolution ca. 7 Ma (early Messinian). suggest studied may barrier for upward migration deep fluids at hypocentral depth present-day earthquakes. speculate similar zones have overall regional seismotectonic pattern causing transient overpressures and, possibly, triggering cyclic earthquakes normal faults prone while crosscutting earlier (as per classic valve behavior). This mechanism controlled origin 2016−2017 devastating