Frictional controls on the seismogenic zone: Insights from the Apenninic basement, Central Italy

Volpe, G.; Pozzi, Giacomo; Carminati, Eugenio; Barchi, Massimiliano Rinaldo; Scuderi, M. M.; Tinti, Elisa; Aldega, Luca; Marone, Chris; Collettini, Cristiano

doi:10.1016/j.epsl.2022.117444

Cited by 17 publications

(6 citation statements)

References 76 publications

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“…The Apennines are a region of thin‐skinned backarc extension driven by lithospheric mantle delamination associated with the Adria slab retreat (e.g., Jolivet et al., 2013; D’Acquisto et al., 2020). Structurally, this region is characterized by normal faulting that accommodates upper crustal thinning on top of a sub‐horizontal mid‐crustal detachment at ∼9 km depth (Scrocca et al., 2005; Volpe et al., 2022; Waldhauser et al., 2021). The pattern of closely spaced parallel NW‐SE striking normal faults and the surface strain rate data (Kreemer et al., 2014a) testify a near plane strain horizontal deformation field with a relatively low PHSR of about 0.36 (Figures 8c and 8e).…”

Section: Discussionmentioning

confidence: 99%

Fault Networks in Triaxial Tectonic Settings: Analog Modeling of Distributed Continental Extension With Lateral Shortening

Liu,

Rosenau,

Brune

et al. 2024

Tectonics

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Triaxial deformation is a general feature of continental tectonics, but its controls and the systematics of associated fault networks remain poorly understood. We present triaxial analog experiments mimicking crustal thinning resulting from distributed longitudinal extension and lateral shortening. Contemporary longitudinal extension and lateral shortening are related by the principal horizontal strain ratio (PHSR). We investigate the effect of crustal geometry, rheology and strain rate on deformation localization, faulting regime and pattern, and PHSR in brittle and brittle‐viscous crustal‐scale models. We find that in brittle models the fault networks reflect the basal boundary condition and fault‐density scales inversely with brittle layer thickness. In brittle‐viscous models, as strain rate (ė) decreases, (a) Three fault patterns emerge: conjugate sets of strike‐slip faults (ė > 3 × 10−4 s−1, PHSR > 0.31), sets of parallel oblique normal faults (ė = 0.3–3 × 10−4 s−1, PHSR = 0.15–0.25), horst‐and‐graben system (ė < 0.3 × 10−4 s−1, PHSR < 0.1). (b) The strain localization increases systematically and gradually. We interpret the strain rate dependent of faulting regimes to be controlled by vertical coupling between the model upper mantle and model upper crust resulting in spontaneous permutation of principal stress axes. Rate‐dependency of strain localization can be related to mechanical coupling between the upper and lower crust. We identify the following parameters controlling triaxial tectonic deformation: upper crustal thickness and friction coefficient, lower crustal thickness and viscosity, as well as strain rate. We test our models and predictions against natural prototypes (Tibet, Anatolia, Apennines, and Basin and Range Province) thus providing new perspectives on triaxial deformation.

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Section: Discussionmentioning

confidence: 99%

Fault Networks in Triaxial Tectonic Settings: Analog Modeling of Distributed Continental Extension With Lateral Shortening

Liu,

Rosenau,

Brune

et al. 2024

Tectonics

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“…In other portions these zones are confined at depth by the top of the basement (Supplementary Note 2 and Supplementary Fig. 3 ), where frictionally stable, foliated, and phyllosilicate-rich horizons favour aseismic deformation 49 .…”

Section: Discussionmentioning

confidence: 99%

Rock and fault rheology explain differences between on fault and distributed seismicity

et al. 2022

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Analysis of seismicity can illuminate active fault zone structures but also deformation within large volumes of the seismogenic zone. For the Mw 6.5 2016–2017 Central Italy seismic sequence, seismicity not only localizes along the major structures hosting the mainshocks (on-fault seismicity), but also occurs within volumes of Triassic Evaporites, TE, composed of alternated anhydrites and dolostones. These volumes of distributed microseismicity show a different frequency-magnitude distribution than on-fault seismicity. We interpret that, during the sequence, shear strain-rate increase, and fluid overpressure promoted widespread ductile deformation within TE that light-up with distributed microseismicity. This interpretation is supported by field and laboratory observations showing that TE background ductile deformation is complex and dominated by distributed failure and folding of the anhydrites associated with boudinage hydro-fracturing and faulting of dolostones. Our results indicate that ductile crustal deformation can cause distributed microseismicity, which obeys to different scaling laws than on-fault seismicity occurring on structures characterized by elasto-frictional stick-slip behaviour.

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“…In other portions these thick zones of diffuse microseismicity are con ned at depth by the top of the basement (Supplementary Fig. 1), where frictionally stable, foliated, and phyllosilicate-rich horizons favour aseismic deformation 47 .…”

Section: Discussionmentioning

confidence: 99%

On fault vs. off-fault seismicity: the role of rock vs. fault rheology

Collettini

Paola

Barchi

et al. 2022

Preprint

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Analysis of seismicity can illuminate active fault zone structures but also pervasive deformation occurring within large volumes of the seismogenic zone. Here we show that, for the Mw 6.5 2016–2017 Central Italy seismic sequence, seismicity not only localizes along SW-dipping normal faults, but also occurs within larger volumes of Triassic Evaporites, TE, composed of alternated anhydrites and dolostones. This off-fault and diffuse microseismicity shows a different frequency-magnitude distribution than on-fault seismicity along the structures hosting the largest events. We interpret that, during the sequence, shear strain-rate increase promoted widespread ductile deformation within TE that light-up with diffuse microseismicity. This interpretation is supported by field and laboratory observations showing that TE background ductile deformation is complex and dominated by distributed failure and folding of the anhydrites associated with boudinage fracturing and faulting of dolostones. Our results indicate that ductile crustal deformation can cause off-fault and diffuse microseismicity, which obeys to different scaling laws than on-fault seismicity on structures characterized by elasto-frictional stick-sip behaviour.

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Frictional controls on the seismogenic zone: Insights from the Apenninic basement, Central Italy

Cited by 17 publications

References 76 publications

Fault Networks in Triaxial Tectonic Settings: Analog Modeling of Distributed Continental Extension With Lateral Shortening

Fault Networks in Triaxial Tectonic Settings: Analog Modeling of Distributed Continental Extension With Lateral Shortening

Rock and fault rheology explain differences between on fault and distributed seismicity

On fault vs. off-fault seismicity: the role of rock vs. fault rheology

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