Interseismic coupling for the Altotiberina Fault from GPS data

Abstract

The Umbria-Marche Apennines is a region characterized by strong historical and instrumental earthquakes located in a complex tectonic framework where both extensional and compressional activities are taken up. Moreover a particular fault structure, the Altotiberina fault (ATF), seems to play an active role within this tectonic extension, even if it is still not clear whether this structure is active or able to generate big earthquakes. Nevertheless which of the known fault systems play a major role in accommodating the extension, and which are the modes (seismic VS aseismic deformation) this extension is taken up, are still debated topics. Using a dense network of high-precision GPS measurements and a kinematic block modeling approach, this study evaluates which fault systems can better explain the crustal deformation observed by geodetic data. Inferring a tectonic activity of the ATF within this context, we evaluate its interseismic coupling distribution, and the resolution capability due to the spatial distribution of data. A wide portion of ATF, well resolved by data, is aseismically creeping, whereas for the first 4–5km of depth seems fully locked, providing new clues on its seismic potential.