Relationship between topography, rates of extension and mantle dynamics in the actively-extending Italian Apennines

To investigate the mechanism driving active extension in the central and southern Italian Apennines and the geography of seismic hazard, we compare spatial variations in upper crustal strain-rate measured across exposed fault scarps since 15±3ka with data on cumulative upper-crustal strain and topographic elevation, and free-air gravity, P-wave tomography and SKS splitting delay times that are a proxy for strain in the mantle. High extensional strain-rates across the Apennines since 15±3ka (0.4–3.1mm/yr along 90km transects) occur in two areas (Lazio-Abruzzo; SE Campania and Basilicata) where values for finite extensional strains that have developed since 2–3Ma are highest (2–7km cumulative throw), and where mean elevation in 5×90km NE–SW boxes is >600m; the intervening area (NW Campania and Molise) with