The May 20 (MW 6.1) and 29 (MW 6.0), 2012, Emilia (Po Plain, northern Italy) earthquakes: New seismotectonic implications from subsurface geology and high-quality hypocenter location

Carannante, Simona; Argnani, Andrea; Massa, Marco; D’Alema, Ezio; Lovati, Sara; Moretti, Milena; Cattaneo, M.; Augliera, P.

doi:10.1016/j.tecto.2015.05.015

Cited by 27 publications

(33 citation statements)

References 52 publications

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“…In particular, rather than being associated with the eastward migration of the back‐arc extensional tectonic regime (e.g., Elter et al, ; Patacca et al, ), earthquakes occurring along fault zones dissecting thrust‐related anticlines close to the mountain front could be triggered by out‐of‐sequence underthrusting at depth, causing episodic gravitational reequilibration in the overlying stacked thrust sheets. In this view, seismicity in this region would be mainly driven by the dynamics of the Adriatic foreland more than by Tyrrhenian extension , in the same way of offshore earthquakes (e.g., Carannante et al, ; Chiarabba et al, ; Mazzoli et al, ). The presence of multiple thrust sheets underneath exposed thrust‐related folds is well documented for many major structures like the Maiella anticline (e.g., Patacca et al, ), the Gran Sasso thrust sheet (e.g., Cosentino et al, ; Ghisetti et al, ), and the Acquasanta anticline (e.g., Ghisetti & Vezzani, ), to the west of the Montagna dei Fiori (Figure a).…”

Section: Discussionmentioning

confidence: 99%

Syn‐Contractional Overprinting Between Extension and Shortening Along the Montagna Dei Fiori Fault During Plio‐Pleistocene Antiformal Stacking at the Central Apennines Thrust Wedge Toe

et al. 2018

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The Montagna dei Fiori fault vertically offsets the crest of the NW-SE trending Montagna dei Fiori anticline in the distal foothills of the central Apennines. There are several interpretations to explain this extensional fault system in close proximity to the Apennine deformation front. A prefolding age of the Montagna dei Fiori fault prevails in models and ideas, based on evidence of Triassic to Early Jurassic rift-related faults and on thickness and facies distribution of Miocene sediments. However, overprint relationships between extension and shortening are generally speculative and relative age constraints are loose. In this paper we provide an alternative interpretation based on new structural and geochemical data that does not support any preshortening scenarios. The outcrops show that (1) failure of the prerift to syn-rift Jurassic platform carbonates is controlled by a pattern of~N-S and E-W fault trends, (2) cessation of fault activity coincides with a breakup unconformity of Late Jurassic age, and (3) a large variety of S-C shear fabrics occurs along the Montagna dei Fiori fault. Petrography, C-O stable isotope, and microthermometric data of calcite veins provide constraints on the environmental conditions of deformation. Our multidisciplinary data set favors a partitioning of strain by the interaction of horizontal shortening and related uplift, and by gravitational reequilibration controlled by antiformal stacking underneath the Montagna dei Fiori anticline. Therefore, shortening and extensional strain fields are genetically connected, coeval, while nucleating from different levels in the mechanical stratigraphy. We discuss the implications of this model on the seismo-tectonic framework of active faulting in the central Apennines of Italy.

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Section: Discussionmentioning

confidence: 99%

Syn‐Contractional Overprinting Between Extension and Shortening Along the Montagna Dei Fiori Fault During Plio‐Pleistocene Antiformal Stacking at the Central Apennines Thrust Wedge Toe

et al. 2018

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“…The stiffness of layer 1 (Quaternary) is constrained with experimental data from a sonic log [ Maesano and D'Ambrogi , ]. Stiffness for layers 2 to 5 are constrained according to an up‐to‐date seismic velocity model obtained in the study area after the 2012 seismic sequence [ Carannante et al , ] (Figure S4). Then, dynamic Young moduli (Table ) are converted to static Young moduli according to the empirical relationship proposed by Brotons et al [] (equation ):

E_{st} = 11.531 ∙ ρ^{- 0.457} ∙ E_{dyn}^{1.251}

where E st is the static Young modulus, ρ is the mass density and E dyn is the dynamic Young modulus (Figure S5).…”

Section: Methodsmentioning

confidence: 99%

Aftershocks, groundwater changes and postseismic ground displacements related to pore pressure gradients: Insights from the 2012 Emilia‐Romagna earthquake

et al. 2017

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During the 2012 Emilia‐Romagna (Italy) seismic sequence, several time‐dependent phenomena occurred, such as changes in the groundwater regime and chemistry, liquefaction, and postseismic ground displacements. Because time‐dependent phenomena require time‐dependent physical mechanisms, we interpreted such events as the result of the poroelastic response of the crust after the main shock. In our study, we performed a two‐dimensional poroelastic numerical analysis calibrated with Cosmo‐SkyMed interferometric data and measured piezometric levels in water wells. The simulation results are consistent with the observed postseismic ground displacement and water level changes. The simulations show that crustal volumetric changes induced by poroelastic relaxation and the afterslip along the main shock fault are both required to reproduce the amplitude (approximately 4 cm) and temporal evolution of the observed postseismic uplift. Poroelastic relaxation also affects the aftershock distribution. In fact, the aftershocks are correlated with the postseismic Coulomb stress evolution. In particular, a considerably higher fraction of aftershocks occurs when the evolving poroelastic Coulomb stress is positive. These findings highlight the need to perform calculations that adequately consider the time‐dependent poroelastic effect when modeling postseismic scenarios, especially for forecasting the temporal and spatial evolution of stresses after a large earthquake. Failing to do so results in an overestimation of the afterslip and an inaccurate definition of stress and strain in the postseismic phase.

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“…Fault plane solutions of major instrumental earthquakes show prevailing compressional mechanisms (Pondrelli, Salimbeni, Perfetti, & Danecek, ; Scognamiglio et al, ). A marked uplift of the ground (up to 17 cm) was measured around the epicentral area of the 2012 events (maximum magnitude Mw ~ 6.1 on May 20; Anzidei, Maramai, & Montone, ; Carannante et al, ) through DInSAR technique and high‐precision levelling (Bignami et al, ; Caputo et al, ; Salvi et al, ). Nevertheless, the entire Po Plain is subsiding (up to 2.5 mm/year over the last 1.43 Myr, Carminati & Di Donato, ), due to the combined effect of flexural subsidence and sediment compaction.…”

Section: Geological Settingmentioning

confidence: 99%

Peat layer accumulation and post‐burial deformation during the mid‐late Holocene in the Po coastal plain (Northern Italy)

et al. 2019

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Peat horizons are characteristic features of delta plains worldwide. In this study, we tested the use of peat‐based correlations to assess the deformation of Holocene strata in the Po coastal plain (Northern Italy). The Holocene stratigraphy, about 30 km inland from the modern coastline consists of a peat‐bearing, estuarine and deltaic succession, up to 23 m thick. Through the analysis of 31 core data and 100 piezocone penetration tests, we identified and mapped three 10–40 cm‐thick peat layers (T1–T3) dated to 6.6–5.8, 5.5–5.0 and 3.3–2.7 cal kyr BP respectively. These peat horizons were found to be suitable stratigraphic markers within the Holocene succession over an area of about 200 km2. The mid‐late Holocene palaeogeography, reconstructed through high‐resolution peat correlation, supported by 72 radiocarbon dates, highlights a typical upper delta plain environment, with ribbon‐shaped distributary channels and swamp interdistributary areas. Peat layers are inclined towards E‐NE with gradients that increase downsection from ~0.016% (T3) to 0.021% (T1). The gradient of the oldest peat horizon is one order of magnitude larger than the slope of the modern delta plain (~0.0025%). We infer that peat horizons accumulated during periods of low sediment supply mainly controlled by autogenic processes and were deformed after deposition. Differential compaction of underlying sedimentary strata and recent tectonic activity of the buried Apenninic thrust systems are the most likely drivers of strata deformation. Based on isochore maps, we document that higher sedimentation rates in topographically depressed areas compensated, in part at least, the ongoing deformation, keeping unaltered the topographic gradient and the depositional environment. This study demonstrates that peat‐based correlation and mapping can shed lights on the mechanisms of strata accumulation and deformation in deltaic settings, constituting a robust basis for reconstructing delta evolution.

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The May 20 (MW 6.1) and 29 (MW 6.0), 2012, Emilia (Po Plain, northern Italy) earthquakes: New seismotectonic implications from subsurface geology and high-quality hypocenter location

Cited by 27 publications

References 52 publications

Syn‐Contractional Overprinting Between Extension and Shortening Along the Montagna Dei Fiori Fault During Plio‐Pleistocene Antiformal Stacking at the Central Apennines Thrust Wedge Toe

Syn‐Contractional Overprinting Between Extension and Shortening Along the Montagna Dei Fiori Fault During Plio‐Pleistocene Antiformal Stacking at the Central Apennines Thrust Wedge Toe

Aftershocks, groundwater changes and postseismic ground displacements related to pore pressure gradients: Insights from the 2012 Emilia‐Romagna earthquake

Peat layer accumulation and post‐burial deformation during the mid‐late Holocene in the Po coastal plain (Northern Italy)

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