We present a 2-D subsurface image of the Paganica Fault from a high-resolution refraction tomography and detailed geological investigation carried out across part of the northwestern segment of the 20-km-long Paganica-San Demetrio fault-system, and which was responsible of the 2009 April 6 Mw 6.1 L'Aquila earthquake (central Italy). We acquired two seismic profiles crossing the Paganica basin with a dense-wide aperture configuration. More than 30 000 P wave first-arrival traveltimes were input to a non-linear tomographic inversion. The obtained 250-300 m deep 2-D Vp images illuminate the shallow portion of the Paganica Fault, and depict additional unreported splays defining a complex half-graben structure. We interpret local thickening of low-Vp (<2400 m s-1) and intermediate-Vp (2600-3400 m s-1) regions as syn-tectonic clasticwedges above a high-Vp (3800-5000ms-1) carbonate basement. These results are condensed in a 4.2-km-long section across the Paganica basin, clearly indicating that the Paganica Fault is a mature normal fault cutting the whole upper 10 km of the crust. We evaluate a minimum cumulative net displacement of 650 ± 90 m and a total heave of 530 ± 65 m accomplished by the Paganica Fault, respectively. In the conservative hypothesis that the extension started during the Gelasian (1.80-2.59 Ma),we obtain a minimum long-term slip-rate of 0.30 ± 0.07 mm yr-1 and an extension-rate of 0.25 ± 0.06 mm yr-1, respectively. Considering the regional averaged extensional field of 1 mm yr-1 obtained from geodetic and geological analyses at 104 yr timescale, we infer that the Paganica Fault accounts for 20 per cent of the NE-extension affecting this zone of the central Apennines axis due to the concurrent activity of other parallel normal fault-systems nearby (e.g. the Liri, Velino-Magnola, L'Aquila-Celano and Gran Sasso fault-systems).

Investigating the architecture of the Paganica Fault (2009Mw 6.1 earthquake, central Italy) by integrating high-resolution multiscale refraction tomography and detailed geological mapping / Villani, F.; Improta, L.; Pucci, S.; Civico, R.; Bruno, P. P. G.; Pantosti, D.. - In: GEOPHYSICAL JOURNAL INTERNATIONAL. - ISSN 0956-540X. - 208:1(2017), pp. 403-423. [10.1093/gji/ggw407]

Investigating the architecture of the Paganica Fault (2009Mw 6.1 earthquake, central Italy) by integrating high-resolution multiscale refraction tomography and detailed geological mapping

Bruno P. P. G.;
2017

Abstract

We present a 2-D subsurface image of the Paganica Fault from a high-resolution refraction tomography and detailed geological investigation carried out across part of the northwestern segment of the 20-km-long Paganica-San Demetrio fault-system, and which was responsible of the 2009 April 6 Mw 6.1 L'Aquila earthquake (central Italy). We acquired two seismic profiles crossing the Paganica basin with a dense-wide aperture configuration. More than 30 000 P wave first-arrival traveltimes were input to a non-linear tomographic inversion. The obtained 250-300 m deep 2-D Vp images illuminate the shallow portion of the Paganica Fault, and depict additional unreported splays defining a complex half-graben structure. We interpret local thickening of low-Vp (<2400 m s-1) and intermediate-Vp (2600-3400 m s-1) regions as syn-tectonic clasticwedges above a high-Vp (3800-5000ms-1) carbonate basement. These results are condensed in a 4.2-km-long section across the Paganica basin, clearly indicating that the Paganica Fault is a mature normal fault cutting the whole upper 10 km of the crust. We evaluate a minimum cumulative net displacement of 650 ± 90 m and a total heave of 530 ± 65 m accomplished by the Paganica Fault, respectively. In the conservative hypothesis that the extension started during the Gelasian (1.80-2.59 Ma),we obtain a minimum long-term slip-rate of 0.30 ± 0.07 mm yr-1 and an extension-rate of 0.25 ± 0.06 mm yr-1, respectively. Considering the regional averaged extensional field of 1 mm yr-1 obtained from geodetic and geological analyses at 104 yr timescale, we infer that the Paganica Fault accounts for 20 per cent of the NE-extension affecting this zone of the central Apennines axis due to the concurrent activity of other parallel normal fault-systems nearby (e.g. the Liri, Velino-Magnola, L'Aquila-Celano and Gran Sasso fault-systems).
2017
Investigating the architecture of the Paganica Fault (2009Mw 6.1 earthquake, central Italy) by integrating high-resolution multiscale refraction tomography and detailed geological mapping / Villani, F.; Improta, L.; Pucci, S.; Civico, R.; Bruno, P. P. G.; Pantosti, D.. - In: GEOPHYSICAL JOURNAL INTERNATIONAL. - ISSN 0956-540X. - 208:1(2017), pp. 403-423. [10.1093/gji/ggw407]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/777248
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