Driving mechanism of tectonic activity in the northern Apennines: Quantitative insights from numerical modeling

Abstract

[1] It is shown, by numerical modeling, that the recent deformation pattern observed in the northern Apennines, mainly characterized by progressive eastward migration and bowing of the belt, thrusting activity along its external front, and tensional tectonics in the internal area, can be reproduced, at a first approximation, by applying a belt-parallel (SE-NW) compression to the chain, which is simulated as a structural system characterized by a high mechanical strength and decoupled from the surrounding zones. The above compressional regime, obtained by imposing kinematic boundary conditions to the model, causes the outward escape of crustal wedges from the chain, in particular the northeastward displacement of the Romagna-Marche-Umbria Units and the counterclockwise rotation and northwestward displacement of the Ligurian Units. This kinematics produces compressional to transcompressional strain along the external front of the chain and tensional to transtensional strain in the internal area, in line with the observed features that concern both strain style and orientation of principal strains. Evidence and arguments supporting the kinematic boundary conditions and the model parameterization adopted in modeling are discussed. Numerical experiments have also been carried out to evaluate the influence of major features of the model parameterization and boundary conditions we have adopted in modeling and to provide insights into the possible influence of strong decoupling earthquakes in the central Apennines on tectonic and seismic activity in the northern Apennines.

Plate kinematics and geodynamics in the Central Mediterranean

“…The latest phase of such evolutionary reconstruction is also quantitatively supported by the results of numerical modelling of the Quaternary tectonic setting in the Central and Eastern Mediterranean regions (Mantovani et al, 2001a;Viti et al, 2004). The long-term kinematic pattern resulting from the above analyses, updated in several aspects, is shown in Fig.…”

Long-term earthquake triggering in the Southern and Northern Apennines

“…1 and 2) suggests that the deformation and associated seismic activity in the Northern Apennines is mainly driven by the indentation of the eastern part of the LA platform. A detailed description of the evidence and arguments that support this interpretation is given by Viti et al (2004Viti et al ( , 2006 and Cenni et al (2008). When a strong decoupling earthquake occurs along one of the two main shear zones longitudinally cutting the LA platform, the corresponding decoupled ELA block accelerates, causing an increase of stress and possibly of seismotectonic activity in the Northern Apennines.…”

“…The subsequent event occurred in the internal extensional border of that wedge (Northern Tiber trough, 1917, M = 5.7). The Forlivese zone, where the third major earthquake took place (1918, M = 5.7), probably corresponds to the transpressional decoupling belt between the RMU and Ligurian units (Costa 2003;Viti et al 2004). The last two major events of the 1916-1920 sequence took place along the internal extensional border of the Ligurian wedge (Mugello, 1919, M = 6.2 andGarfagnana, 1920, M = 6.5), suggesting that the above phase also involved an outward displacement of that wedge.…”

Strain Diffusion from the 30 October 2016 Norcia (Central Italy) Earthquake

“…In this work we have used the commercial software TWODEPEP® (Sewell, ; Viti et al, , , , ). The implicit Crank‐Nicolson solution method has been adopted in order to discretize time, and to reduce the parabolic form of the above‐mentioned partial differential equations to a nonhomogeneous elliptic form (Morton & Mayers, ; Sewell, ).…”