Repeated reactivation in the Apennine-Maghrebide system, Italy: a possible example of fault-zone weakening?

Tavarnelli, Enrico; Decandia, F. A.; Renda, Pietro; Tramutoli, Mariano; Gueguen, E.; Alberti, Mauro

doi:10.1144/gsl.sp.2001.186.01.16

Cited by 23 publications

(20 citation statements)

References 24 publications

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“…The structure includes E-verging folds and NS-trending thrust faults, linked by SW-NE-trending right strike-slip faults (Decandia et al, 1980;Decandia, 1982). Its average SSW-NNE direction is oblique with respect to the SW-NE direction of tectonic transport, inferred from mesostructural evidence (Tavernelli et al, 2001).…”

Section: Regional Geological Setting and Seismicitymentioning

confidence: 94%

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

et al. 2006

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Results of geological, geomechanical and seismometric investigations aiming at the analysis of the seismic response in a carbonate ridge of the Nera River valley (Central Apennines -Italy) are discussed. Geological and geomechanical surveys were aimed at defining the stratigraphic and structural setting of the outcropping formations and the jointing conditions of the rock mass. Velocimetric records of both ambient noise and small-magnitude earthquakes were analysed in order to identify amplification conditions. The analysis was carried out in the time domain, through directional energy evaluation, and in the frequency domain, through H/V spectral ratios and spectral ratios with respect to a reference station. A local amplification factor was estimated from Housner intensity. The study revealed a significant seismic amplification in a fault zone. This effect was observed in intensely jointed and mylonitic rock masses, located inside moderately jointed rock masses, and is the result of specific geometries and significant impedance contrasts. A map of fault zones prone to amplification of ground motion was constructed, taking into account the jointing conditions of the rock masses and the structural setting of the investigated ridge. The study relied on an integrated methodological approach, which combined the available data under union and intersection criteria.

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Section: Regional Geological Setting and Seismicitymentioning

confidence: 94%

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

et al. 2006

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“…2a) hosts a main thrust associated with E-verging folds and north-south trending thrust faults linked by southwest-northeast trending right strike-slip faults (Decandia et al, 1980;Decandia, 1982;Barchi et al, 1993Barchi et al, , 2000. Its average south-southwest-north-northeast direction is oblique with respect to the southwest-northeast direction of tectonic transport, inferred from mesostructural evidences (Tavarnelli et al, 2001).…”

Section: Engineering Geology Model Of the Cerreto DI Spoleto Alluvialmentioning

confidence: 95%

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Lenti

Martino²,

Paciello

et al. 2009

Bulletin of the Seismological Society of America

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The results of field surveys, velocimetric records, and numerical models are reported with the goal of analyzing the local seismic response in a section of the Nera River alluvial valley in central Italy. Alluvial deposit geometry and dynamic properties were defined by geological and geophysical investigations. 2D amplification effects were pointed out by horizontal-to-vertical spectral ratios (HVSRs) as well as by horizontal-to-horizontal spectral ratios (HHSRs) to a reference station; HVSRs were derived from both noise and weak-motion records, while HHSRs were only computed from weak motions. Where travertine deposits are interlayered within the alluvia, 2D amplification effects are shown only by HHSRs. The observed amplifications: (1) consist of peaks of the amplification functions A (f) in the range 1-10 Hz, (2) generally correspond to two frequency ranges whose values mainly depend on the valley shaped ratio and on the local heterogenities of the alluvial deposits, and (3) can be regarded as due to a 1D resonance combined with lateral wave propagation. Numerical models via the finite difference method were performed by the Italian National Institute for Geophysics and Volcanology-Web Interface for Seismological Application and by the Fast Lagrangian Analysis of Continua codes. The obtained results: (1) show a good agreement with HHSRs, (2) prove that some 2D amplification effects are constrained by both the shape ratio of the valley and the heterogeneity of the alluvial deposits, (3) reveal focalization effects within the alluvial deposits strictly related to the shape of the valley, and (4) allow the comparison of the A(f) functions in both linear and nonlinear dynamic behavior and the computation of the shear strains due to ground motion within the alluvial deposits

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“…Shortening is difficult to estimate in the northern Apennines due to contractional reactivation of preorogenic normal faults as thrusts (e.g., Tavarnelli et al, ) and to subsequent extensional reactivation of these thrusts during rollback subduction (e.g., Brogi & Liotta, ). This makes tectonostratigraphic markers unreliable for estimating thrust displacement.…”

Section: New Constraints On Post‐20 Ma Adria Motionmentioning

confidence: 99%

Post‐20 Ma Motion of the Adriatic Plate: New Constraints From Surrounding Orogens and Implications for Crust‐Mantle Decoupling

et al. 2017

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A new kinematic reconstruction that incorporates estimates of post‐20 Ma shortening and extension in the Apennines, Alps, Dinarides, and Sicily Channel Rift Zone (SCRZ) reveals that the Adriatic microplate (Adria) rotated counterclockwise as it subducted beneath the European Plate to the west and to the east, while indenting the Alps to the north. Minimum and maximum amounts of rotation are derived by using, respectively, estimates of crustal extension along the SCRZ (minimum of 30 km) combined with crustal shortening in the Eastern Alps (minimum of 115 km) and a maximum amount (140 km) of convergence between Adria and Moesia across the southern Dinarides and Carpatho‐Balkan orogens. When combined with Neogene convergence in the Western Alps, the best fit of available structural data constrains Adria to have moved 113 km to the NW (azimuth 325°) while rotating 5 ± 3° counterclockwise relative to Europe since 20 Ma. Amounts of plate convergence predicted by our new model exceed Neogene shortening estimates of several tens of kilometers in both the Apennines and Dinarides. We attribute this difference to crust‐mantle decoupling (delamination) during rollback in the Apennines and to distributed deformation related to the northward motion of the Dacia Unit between the southern Dinarides and Europe (Moesia). Neogene motion of Adria resulted from a combination of Africa pushing from the south, the Adriatic‐Hellenides slab pulling to the northeast, and crustal wedging in the Western Alps, which acted as a pivot and stopped farther northwestward motion of Adria relative to Europe.

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Repeated reactivation in the Apennine-Maghrebide system, Italy: a possible example of fault-zone weakening?

Cited by 23 publications

References 24 publications

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

Evidence of Amplification Effects in Fault Zone Related to Rock Mass Jointing

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Post‐20 Ma Motion of the Adriatic Plate: New Constraints From Surrounding Orogens and Implications for Crust‐Mantle Decoupling

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