Seismogenic compression in southern Italy? Morphotectonic analysis to detect possible evidence of Late Quaternary tectonics along the Southern Apennine Outer Front

Federica Ferrarini, Ramon Arrowsmith, Francesco Brozzetti, Rita de Nardis, Daniele Cirillo, & Giusy Lavecchia

Published August 15, 2019, SCEC Contribution #9738, 2019 SCEC Annual Meeting Poster #128

Earthquakes are a major natural hazard for the Mediterranean area and Italy is one of the countries where they still belong among the deadliest disasters. Earthquakes occurred in the last fifteen years in central-southern Italy (S. Giuliano di Puglia 2002 Mw 5.4, l’Aquila 2009 Mw 6.3, Norcia 2016 Mw 6.5) confirm the significant vulnerability of buildings, even when exposed to moderately energetic shocks. Additionally, in some areas, peculiar geological setting and low-deformation rates often challenge the need to outline active faults. The Apennine compressional Outer Front (AOF) well fits this frame.

The AOF traverses the mainland Italy and connects with the E-W Maghrebian chain in Sicily. It is clearly seismogenic along the northern and central sectors and similar behaviour is attributed to the Sicilian Outer Front. Differently, it is often considered inactive in southern Italy (SAOF) where the orogenic activity ceased at the beginning of the Middle Pleistocene and the front is buried under Plio-Quaternary foredeep successions. This setting agrees with the lack of recent compressive instrumental seismicity along the SAOF.

We started to investigate part of this structural element (Abruzzo and Molise regions) along the Adriatic piedimont and in the foolthill areas where a tectonic uplift phase is reported in the Middle-Late Pleistocene (0.2 mm/y). We performed morphometric analysis on the fluvial network to detect possible transient response to late Quaternary tectonic activity. As well, we used the distribution of normalized channel steepness index to infer relative magnitudes of rock uplift. We compared map distribution of knick points, ksn values and relief maps along with the main geological, lithological and structural features known for the area.

Our approach in the study area highlighted as smaller rivers flowing in the piedimont/coastal sectors, tend to show vertical step- knick points, especially along their tributaries, and despite to the clayey lithology. Differently, rivers characterized by wide catchments mostly exhibit anomalous convexities (upstream in the trunk and in a more inner position, e.g. Frentani Mts area), suggesting possible ‘non equilibium’ conditions. Both the channel stepness- and relief maps are consistent with these results. These results seem to suggest locally higher rock uplift rates, supporting the existence of tectonic signals related to Late Quaternary shortening along the SAOF.

Key Words
Active tectonics, tectonic geomorphology, Southern Apennines, Italy

Citation
Ferrarini, F., Arrowsmith, R., Brozzetti, F., de Nardis, R., Cirillo, D., & Lavecchia, G. (2019, 08). Seismogenic compression in southern Italy? Morphotectonic analysis to detect possible evidence of Late Quaternary tectonics along the Southern Apennine Outer Front. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology