The Italian Apennines Quaternary extension was accommodated by the formation of both high-angle (westdipping) and moderate- to low-angle (east-dipping) normal and normal-oblique faults that cross-cut and offset Mio-Pliocene fold-and-thrust structures. This extensional (east-dipping) detachment structure in Northern Italy is known as Etrurian Fault System (EFS). The EFS represents a regional NNW–SSE fault alignment, which has less-evident field expressions (cropping out along the western border of the Apennine belt), and extends from north to south from the extensional Lunigiana–Garfagnana basins to the Mugello–Casentino ones to the western border of the Eastern Tiber basin. The counterpart Central Italy structure, known as Latium-Abruzzo Extensional Detachment (LAED; Lavecchia et al., 2017), crops out in the Sabini-Eastern Simbruini (SES) and it is supposed to continue at mid-crustal depths beneath the L’Aquila 2009 (Mw6.3) epicentral area. The LAED would represent a regional right-lateral en echelon arm of the EFS. Potentially seismogenic moderate- to low-angle east-dipping normal faults are also located in Southern Italy, along the Campania-Lucania Extensional Fault System (CLEFS; Brozzetti, 2011). These faults were responsible for the 1980 Irpinia earthquake (Mw6.8). In the Central and Southern Apennines eastward of the extensional belt, also active E–W strike-slip faults are recognized. Previous studies investigated how a newly-formed normal fault interacts with structures inherited from a previous contractional phase (Bonini et al., 2015). Here we present the preliminary results of analogue models carried out aiming to reproduce the formation and the downward propagation of a moderate-to low-angle normal main regional fault. Both with the genesis and the evolution of this kind of structure, we investigated also the progressively activation of antithetic normal faults sole to the main east-dipping plain. Models were executed using a device composed by two rigid blocks juxtaposed along sloping sides, which represent the plane of the master fault. The footwall block is fixed, whereas the hangingwall block is allowed to slide downward along the sloping plane (30°); the displacement of the moving block is controlled by a steppermotor at a constant velocity. Wet clay (kaolin) was used as analogue of the rocks above and below the master fault; the use of wet clay allows to insert mechanical discontinuities that simulate pre-existing faults or thin layers of weaker rocks. Then a set of several experiments was performed in order to find the best fitting setup able to reproduce the main extensional (east-dipping) detachment structure.
The Campania-Lucania Extensional Fault System, Southern Italy: an analog modeling perspective
Toscani G.;Bello S.;Lavecchia G.;
2023-01-01
Abstract
The Italian Apennines Quaternary extension was accommodated by the formation of both high-angle (westdipping) and moderate- to low-angle (east-dipping) normal and normal-oblique faults that cross-cut and offset Mio-Pliocene fold-and-thrust structures. This extensional (east-dipping) detachment structure in Northern Italy is known as Etrurian Fault System (EFS). The EFS represents a regional NNW–SSE fault alignment, which has less-evident field expressions (cropping out along the western border of the Apennine belt), and extends from north to south from the extensional Lunigiana–Garfagnana basins to the Mugello–Casentino ones to the western border of the Eastern Tiber basin. The counterpart Central Italy structure, known as Latium-Abruzzo Extensional Detachment (LAED; Lavecchia et al., 2017), crops out in the Sabini-Eastern Simbruini (SES) and it is supposed to continue at mid-crustal depths beneath the L’Aquila 2009 (Mw6.3) epicentral area. The LAED would represent a regional right-lateral en echelon arm of the EFS. Potentially seismogenic moderate- to low-angle east-dipping normal faults are also located in Southern Italy, along the Campania-Lucania Extensional Fault System (CLEFS; Brozzetti, 2011). These faults were responsible for the 1980 Irpinia earthquake (Mw6.8). In the Central and Southern Apennines eastward of the extensional belt, also active E–W strike-slip faults are recognized. Previous studies investigated how a newly-formed normal fault interacts with structures inherited from a previous contractional phase (Bonini et al., 2015). Here we present the preliminary results of analogue models carried out aiming to reproduce the formation and the downward propagation of a moderate-to low-angle normal main regional fault. Both with the genesis and the evolution of this kind of structure, we investigated also the progressively activation of antithetic normal faults sole to the main east-dipping plain. Models were executed using a device composed by two rigid blocks juxtaposed along sloping sides, which represent the plane of the master fault. The footwall block is fixed, whereas the hangingwall block is allowed to slide downward along the sloping plane (30°); the displacement of the moving block is controlled by a steppermotor at a constant velocity. Wet clay (kaolin) was used as analogue of the rocks above and below the master fault; the use of wet clay allows to insert mechanical discontinuities that simulate pre-existing faults or thin layers of weaker rocks. Then a set of several experiments was performed in order to find the best fitting setup able to reproduce the main extensional (east-dipping) detachment structure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
