The evolution of topography in forearc regions results from the complex interplay of crustal and mantle processes. The Southern Apennines represent a well‐studied forearc region that experienced ...several tectonic phases, initially marked by compressional deformation followed by extension and large‐scale uplift. We present a new structural, geomorphic and fluvial analysis of the Pollino Massif and surrounding intermontane basins (Mercure, Campotenese and Castrovillari) to unravel their evolution since the Pliocene. We constrain multiple tectonic transport directions, evolution of the drainage, and magnitude and timing of long‐term incision following base level falls. Two sets of knickpoints suggest two phases of base level lowering and allow to estimate ∼500 m of long‐term uplift (late Pleistocene), as observed in the Sila Massif. On a smaller spatial scale, the evolution and formation of topographic relief, sedimentation, and opening of intermontane basins is strongly controlled by the recent increase in rock uplift rate and fault activity. At the regional scale, an along‐strike, long‐wavelength uplift pattern from north to south can be explained by progressive lateral slab tearing and inflow of asthenospheric mantle beneath Pollino and Sila, which in turn may have promoted extensional tectonics. The lower uplift of Le Serre Massif may be explained as result of weak plate coupling due to narrowing of the Calabrian slab. The onset of uplift in the Pollino Massif, ranging from 400 to 800 ka, is consistent with that one proposed in the southern Calabrian forearc, suggesting a possible synchronism of uplift, and lateral tearing of the Calabrian slab.
Key Points
Topographic evolution constrained by structural, geomorphic and river analysis of the Pollino range and surrounding extensional basins
At short spatial scale, increase in rock uplift and fault activity controls the endorheic‐exorheic transition
At regional scale, uplift increases between 400 and 800 ka, due to progressive lateral slab tearing, and inflow asthenospheric mantle
This work is focused on advanced differential SAR interferometry (DInSAR) techniques for the generation of deformation time series from sequences of SAR images. We first present the basic rationale ...of these techniques providing some details of the most well known algorithms. Subsequently, through the analysis of selected case studies focused on the available C‐band SAR data archives, we show the relevance of the retrieved spatially dense deformation time series for the comprehension of several geophysical phenomena. We finally introduce, again via a real case study, the advances brought in by the new generation X‐band space‐borne SAR sensors, highlighting new investigation possibilities for fast varying deformation phenomena.
In convergent systems, the interplay between tectonics, erosion, and sedimentation controls the orogenic evolution. The nature of the interactions between these factors is still elusive due to the ...complex feedbacks that operate across different temporal and spatial scales. Here, we investigate these feedbacks with analog models of landscape evolution designed to account for both tectonic forcing and surface processes, using a water‐saturated granular material that allows to simulate contemporary brittle deformation and surface processes. The deformation is imposed by the movement of a rigid backstop, and surface processes are triggered by simulated rainfall and runoff. We vary the convergence velocity, rainfall rate, and basal angle of the box, testing how different boundary conditions affect the balance between tectonics and surface processes. We measure the competition between input fluxes (tectonics) and output fluxes (erosion) of material, showing how sedimentation strongly affects the balance between these fluxes. The results suggest that the experimental equilibrium between tectonics and erosion can be achieved, in the analog models, only for low convergence rates (about 10 mm hr−1) and/or for high basal angle (>2°, limited sedimentation). If the foreland is overfilled with sediments and/or if convergence velocity is higher, channels decrease their erosional efficiency, moving the dynamic equilibrium between tectonics and erosion toward the former.
Plain Language Summary
Laboratory models are extremely useful in studying the interaction between processes that build (i.e., tectonics) and processes that carve and shape orogens (i.e., surface processes). We use a rectangular plexiglass box filled with an analog material made of granular materials (silica powder, glass microbeads, and PVC powder) to simulate the building of an accretionary wedge. Surface processes are triggered by a rainfall system above the models, made by commercial sprinklers. To study the interaction between tectonics and surface processes, we change the boundary conditions such as convergence velocity (i.e., the building of the orogenic wedge), and the basal slope (i.e., the inclination of the box toward the foreland). We noticed that the slower the convergence velocity, the higher is the possibility of surface processes adjusting to the tectonic forcing. The capability to remove sediments in front of the accretionary wedge also allows for a stronger response of surface processes to the imposed tectonic forcing.
Key Points
Balance between tectonics and surface processes in analog accretionary wedges, using water‐saturated granular materials
Effect of sedimentation in tuning the balance between tectonics and erosion
Tectonics‐surface processes equilibrium for low analog convergence rates and/or high basal angles (lower sedimentation)
The Moroccan High Atlas, the Anti‐Atlas belts, and the Siroua volcanic massif form an orographic system locally risen to elevations over 4 km. Topographic growth of this system occurred by Cenozoic ...transpressive inversion of Mesozoic rift structures concomitant with volcanic activity and related mantle processes. In order to constrain the topographic growth, we analyze the regional‐scale exhumation pattern, and we compare it to physiographic features. We contribute 35 new mean (U‐Th‐Sm)/He and 24 new fission track ages on apatite from the High Atlas and Anti‐Atlas, which all together range from 196 to 5 Ma. In the Anti‐Atlas, we find that the rate and amount of Cenozoic exhumation are <0.05 km/Ma and ~2 km, respectively. In the High Atlas, our new data together with previous ones show that the axial regions feature the highest topography, relief, channel steepness, and orographic precipitations together with the maximum rate and amount of Cenozoic exhumation, in the range of 0.2–0.3 km/Ma and 4–6 km, respectively. This region is bounded by high‐angle oblique‐slip faults, which display a Neogene vertical motion of a few kilometers. Moreover, the most deeply incised valley in the axial region of the High Atlas shows stepwise cooling and exhumation with a final acceleration after 6 Ma. We conclude that the location in the same region of high river channel steepness, topography, orographic precipitations, and rates and amount of exhumation, together with large vertical offsets along oblique‐slip faults, suggests that crustal deformation may exert a major control on the topographic growth of Atlas orographic swell.
Key Points
Cooling ages constraint the maximum amount of exhumation of 6 km in the axial regions and 4.4 km in the frontal regions of the western High Atlas
Thermal modeling indicates a rapid cooling event at 10 Ma
Morphometric and exhumation pattern indicate remarkable differences along the High Atlas
The High Atlas of Morocco is a double‐vergent mountain belt developed by Cenozoic shortening and inversion of a Triassic‐Jurassic rift. The structural setting, the morphometric features, and the ...patterns of exhumation through time and space change remarkably both along and across the strike. Here we combine structural data with revised thermochronological data to unravel the kinematic and evolution of the western High Atlas. Our results show that the structural grain of the western High Atlas is defined by two main groups of faults, namely, thrust and oblique‐slip faults, which mainly strike subparallel from W‐E to NE‐SW. The slip direction of the thrust structures is NNW‐SSE to NW‐SE oriented, and the slip direction of the oblique‐slip faults is WSW‐ENE to NW‐SE oriented. Pieces of thermochronological and geological evidence indicate that in the last ~10 Ma the exhumation rate increased during the activity thrusts and oblique‐slip faults. The coexistence of these two fault systems also suggests partitioning of deformation under a transpressive regime. In the western High Atlas, we estimate a displacement of ~12 km on the frontal thrusts and of at least ~22 km on the axial oblique‐slip structures. Thrusts and oblique‐slip structures together result in a total cumulative displacement of ~25 km, which represents about half of the Africa‐Eurasia convergence.
Key Points
The western High Atlas builds up under a transpressional regime due to oblique convergence
Using thermochronology and fault kinematics, we infer an overall NW‐SE oriented shortening of ~25 km
The onset of the main deformation event occurred in the middle‐late Miocene
The interaction between sedimentation/erosion and faulting represents one of the most intriguing topics in landscape and tectonics evolution. Only few studies have been able to document the feedback ...between faulting and sedimentary loading from field observations. Here, we focus on how sediment loading/unloading influences the dynamics of fault systems in the Fucino basin, in the Central Apennines (Italy). The Fucino basin represents a remarkable case study with respect to the other main extensional basins in the Apennines because of its large dimension, square shape, significant sediment thickness, and its endorheic nature throughout its evolution.
We present a detailed structural and geomorphologic analysis of the Fucino basin and its surroundings, investigating the kinematic and geometry of each main fault strand. The slickenlines analysis reveals multiple families of slip‐vectors and timing of activity, suggesting a change in extension slip‐direction from N240° to N200° during middle Pleistocene. Using a local isostatic model, we estimate that up to the 30% of the vertical geological displacement of the faults, which overall ranges from 0.5 to 2.5 km, is related to the sediment loading/unloading. We demonstrate a positive feedback between sedimentation and faulting which may also lead to a reorganization in fault kinematics related to a significant increase in vertical stress. We propose a conceptual model for the permanent endorheic configuration of the Fucino basin, which includes the effect of sediment loading.
Key Points
Role of tectonics and drainage systems in the evolution of extensional basins
Extensional fault network and sedimentary loading keep the Fucino basin internally drained during its evolution
Sediment load contributes to incrementing of max 30% the faults total geological throw and locally reorganizes the stress field
The causative source of the first damaging earthquake instrumentally recorded in the Island of Ischia, occurred on 21 August 2017, has been studied through a multiparametric geophysical approach. In ...order to investigate the source geometry and kinematics we exploit seismological, Global Positioning System, and Sentinel‐1 and COSMO‐SkyMed differential interferometric synthetic aperture radar coseismic measurements. Our results indicate that the retrieved solutions from the geodetic data modeling and the seismological data are plausible; in particular, the best fit solution consists of an E‐W striking, south dipping normal fault, with its center located at a depth of 800 m. Moreover, the retrieved causative fault is consistent with the rheological stratification of the crust in this zone. This study allows us to improve the knowledge of the volcano‐tectonic processes occurring on the Island, which is crucial for a better assessment of the seismic risk in the area.
Key Points
Investigation of the ground deformation and source geometry of the 2017 Ischia Island earthquake (Italy) is discussed
The available seismological, GPS, and DInSAR data permit to investigate the causative fault and define its geometry and kinematics
The results suggest that the rheology properties of the crust beneath the Ischia Island have an influence on the volcano‐tectonic processes
Observations from satellites provide high-resolution images of ground deformation allowing to infer deformation sources by developing advanced modeling of magma ascent and intrusion processes. ...Nevertheless, such models can be strongly biased without a precise model of the internal structure of the volcano. In this study, we jointly exploited two interferometric techniques to interpret the 2011–2013 unrest at Campi Flegrei caldera (CFc). The first is the Interferometric Synthetic Aperture Radar (InSAR) technique, which provides highly-resolved spatial and temporal images of ground deformation. The second is the Ambient Noise Tomography (ANT), which images subsurface structures, providing the constraints necessary to infer the depth of the shallow source at CFc (between 0.8 and 1.2 km). We applied for the first time a tool to delineate the deformation source boundaries from the observed deformation maps: the Total Horizontal Derivative (THD) technique. The THD processes the vertical component of the ground deformation field detected through InSAR applied to COSMO-SkyMed data. The patterns retrieved by applying the THD technique show consistent spatial correlations with (1) the seismic group-velocity maps achieved through the ANT and (2) the distribution of the earthquakes nucleated during the unrest at ~1 km. High-velocity anomalies, the retrieved geometrical features of the deformation field, and the spatial distribution of seismicity coincide with extinct volcanic vents in the eastern part of the caldera (Solfatara/Pisciarelli and Astroni). Such a coincidence hints at a significant role of the extinct plumbing system in either constraining or channeling the eastward propagation of magmatic fluids. Here, we demonstrated that a joint analysis of the InSAR patterns, seismic structures, and seismicity allows us to model in space and time the characteristics and nature of the shallow deformation source at CFc. Using published literature, we show that the effects of structural heterogeneities at shallow depths may have a more significant early-stage impact on the evolution of the surface displacement signals than deeper magmatic sources: these secondary structural effects may produce local amplification in the deformation records which can be mistakenly interpreted as early signals of impending eruptions. The achieved results are particularly relevant for the understanding of the origin of deformation signal at volcanoes where magma propagation within sills is expected, as at CFc.
•The joint exploitation of InSAR and ANT allow to detect the source features.•Interferometric technique is Synthetic Aperture Radar to the surface analysis.•The Ambient Noise Tomography to analyze the internal structures.•We analyze di Campi Flegrei caldera during the 2011–2013 unrest episode.
We present an approach to measure 3-D surface deformations caused by large, rapid-moving landslides using the amplitude information of high-resolution, X-band synthetic aperture radar (SAR) images. ...We exploit SAR data captured by the COSMO-SkyMed satellites to measure the deformation produced by the 3 December 2013 Montescaglioso landslide, southern Italy. The deformation produced by the deep-seated landslide exceeded 10 m and caused the disruption of a main road, a few homes and commercial buildings. The results open up the possibility of obtaining 3-D surface deformation maps shortly after the occurrence of large, rapid-moving landslides using high-resolution SAR data.
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