Photo-geology of the Montefalco Quaternary Basin, Umbria, Central Italy

<p>We present a photo-geological map for the 185 km² fault-bounded, Montefalco Basin, Umbria, Central Italy. The basin formed in the Quaternary in response to extensional tectonics dissecting folds and thrusts of the northern Apennines range. To prepare the 1:25,000 geological map, we integrated geological and morphological information obtained through the visual analysis of three sets of aerial photographs of different age, the collection of new field data, and the review of pre-existing surface and sub-surface geological data. We show that systematic interpretation of aerial photographs contributed to improving the geological mapping, providing information not readily available through traditional field mapping. We expect that the new map will be used for different types of geological and geomorphological investigations, including studies of active tectonic, Quaternary morpho-tectonics, sedimentological and stratigraphic analyses, mining and exploration investigations, and the analysis of landslide types, patterns and distribution.</p

Dynamic weakening along incipient low-angle normal faults in pelagic limestones (Southern Apennines, Italy)

<p>Slip along low-angle normal faults is a mechanical paradox requiring activation of strain weakening mechanisms. Microstructures present in the slip zones of incipient low-angle normal faults cutting carbonates in the Southern Apennines of Italy show that slip was promoted by two weakening mechanisms producing a reduction of the friction coefficient: (1) high pore fluid pressures; (2) dynamic weakening related to thermal decomposition indicated by decarbonation microstructures and concomitant localized dynamic calcite recrystallization. Furthermore, as a consequence of thermal decomposition, nanoparticles occur as infilling of injection veins, suggesting that powder lubrication processes are active along the slip surface during seismic slip. </p