THURSDAY 9 FEBRUARY, 4 PM CET (WEBSEMINAR)
Giorgio Arriga
Title: Long-term evolution of seismogenic faults in the central Apennines.
My PhD focuses on studying the long-term evolution of seismogenic faulting in carbonate rocks, specifically in the L’Aquila Intermountain Basin (central Apennines). I combine fieldwork, structural geology, stratigraphy, geochemistry, and geochronology with the goal of understanding how normal fault zones nucleated, propagated, and exhumed during the Pliocene and Quaternary. An important part of my work includes the carbonate geochronology of syn-kinematic structures (U-Th and Thermoluminescence dating) to constrain the age of the tectonic activity. In addition, by integrating Δ47 (clumped isotope) thermometry, it is possible to study the fluid-rock interaction and reconstruct the temperature evolution of the fault zones over time. The main objective of this research is to provide a multidisciplinary, thermal, spatial, and temporal evolutionary model of the seismogenic faults of the central Apennines, contributing to improve both their geodynamic evolution and the regional seismotectonic framework.
The seismogenic fault pattern of the central Apennines of Italy provides a natural laboratory to study interactions and feedbacks between long- and short-term deformation in extensional settings. The Apennines are a Cenozoic orogenic belt, formed by the superposition of multiple oceanic tectonic units, due to the westward subduction of the Adriatic microplate below the Eurasian plate. The central sector (central Apennines) is composed of a fold and thrust belt with a NW-SE direction and a NE vergence, which developed due to a NE-SW compressional phase, that lasted from the late Burdigalian (ca. 18 Ma) until the late Pliocene (ca. 3 Ma). At the end of the mountain building, the Apennines underwent a phase of orogenic collapse, which is the driving mechanism for the present extensional tectonic setting. It was responsible for the opening of several extensional basins located along the axis of the chain, which are filled with alluvial, lacustrine, and slope deposits. These basins are bordered by high angle normal faults that are the seismogenic source for historical and recent seismic events, such as the 2009 (Mw = 6.3) L’Aquila earthquake, and the 2016-2017 (Mw = 6.5) Amatrice-Visso-Norcia seismic sequence. Despite we have a good understanding of the present-day seismic behavior of these faults (short-term), still poorly is known about when faulting started and how it developed in the crust through space and time (long-term evolution).