Structural architecture and active deformation pattern in the northern sector of the Aeolian-Tindari-Letojanni fault system (SE Tyrrhenian Sea-NE Sicily) from integrated analysis of field, marine geophysical, seismological and geodetic data

2017 ◽  
Vol 136 (3) ◽  
pp. 399-417 ◽  
Author(s):  
Fabrizio Cultrera ◽  
Giovanni Barreca ◽  
Luigi Ferranti ◽  
Carmelo Monaco ◽  
Fabrizio Pepe ◽  
...  
Keyword(s):  
Geodetic Data ◽  
Fault System ◽  
Integrated Analysis ◽  
Deformation Pattern ◽  
Tyrrhenian Sea ◽  
Active Deformation ◽  
Ne Sicily ◽  
Structural Architecture ◽  
Northern Sector

scholarly journals Deformation Pattern of the Northern Sector of the Malta Escarpment (Offshore SE Sicily, Italy): Fault Dimension, Slip Prediction, and Seismotectonic Implications

2021 ◽  
Vol 8 ◽  
Author(s):  
Salvatore Gambino ◽  
Giovanni Barreca ◽  
Felix Gross ◽  
Carmelo Monaco ◽  
Sebastian Krastel ◽  
...  
Keyword(s):  
Historical Earthquakes ◽  
Tectonic Activity ◽  
Recurrence Time ◽  
Time Interval ◽  
Deformation Pattern ◽  
Active Deformation ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Bathymetric Grids ◽  
Northern Sector

Marine seismic reflection data coupled with on-land structural measurements improve our knowledge about the active deformation pattern of the northern sector of the Malta Escarpment, a bathymetric and structural discontinuity in the near-offshore of Eastern Sicily. As favourably oriented to be reactivated within the Neogene Africa–Europe convergence, it is believed that the Malta Escarpment has a significant role in the recent seismotectonic framework of the Western Ionian Basin and the Hyblean foreland domain of SE Sicily, where some of the largest and most destructive Mediterranean earthquakes are located according to available historical catalogs. Offshore seismic data along with bathymetric grids illuminate the shallow subseafloor setting and allow more accurate mapping of the seafloor expression of previously identified faults in the area. The seismic interpretation and the near-fault sediment pattern analysis provide constraints on fault 3D geometries as well as on their through-time tectonic activity, suggesting also that part of the observed deformation may have been caused by nontectonic processes. Identified faults form currently an E-dipping, roughly N–S trending, and 60 km-long extensional belt deforming the seafloor with a significant displacement amount in the Ionian offshore between Catania and Siracusa. 3-dimensional parameters of faults were then used to derive expected magnitudes and their reactivation propensity. Empirical scaling relationships and forward methods point to a high seismic potential for the detected fault as well as predict the fault slip behavior according to the field-derived differential stress. This combined analysis along with faults displacement measurements pointed out how the longest and most continuous fault could be capable of generating M > 7 seismic events, putting forward strong seismotectonic implications for the adjacent and densely populated Hyblean Plateau. The expected magnitude and the estimated recurrence time interval are compatible with those inferred for large historical earthquakes in the area even if other offshore seismic sources cannot be ruled out.

scholarly journals Morphostructural, Meteorological and Seismic Factors Controlling Landslides in Weak Rocks: The Case Studies of Castelnuovo and Ponzano (North East Abruzzo, Central Italy)

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 122 ◽  
Author(s):  
Monia Calista ◽  
Enrico Miccadei ◽  
Tommaso Piacentini ◽  
Nicola Sciarra
Keyword(s):  
Central Italy ◽  
Alluvial Fan ◽  
Precipitation Event ◽  
Integrated Analysis ◽  
Deformation Pattern ◽  
Weak Rocks ◽  
Geomorphological Mapping ◽  
North East ◽  
Triggering Factors ◽  
The Stability

We investigated the role of the morphostructural setting and seismic and meteorological factors in the development of landslides in the piedmont of the Abruzzo Apennines. In February 2017, following a heavy snow precipitation event and a moderate seismic sequence (at the end of the Central Italy 2016–2017 seismic crisis), several landslides affected the NE-Abruzzo chain and piedmont area. This work is focused on the Ponzano landslide (Civitella del Tronto, Teramo) and the Castelnuovo landslide (Campli, Teramo) in the NE Abruzzo hilly piedmont. These landslides consist of: (1) a large translational slide-complex landslide, affecting the Miocene–Pliocene sandstone clay bedrock sequence of the piedmont hilly sector; and (2) a complex (topple/fall-slide) landslide, which occurred along a high and steep scarp on conglomerate rocks pertaining to terraced alluvial fan deposits of the Pleistocene superficial deposits. Both of the landslides are typical of the Abruzzo hilly piedmont and both of them largely affected houses and villages located on top of the scarp or within the slope. The landslides were studied by means of field geological and geomorphological mapping, borehole investigations, geostructural analysis and photogeological analysis. For the Ponzano landslide, a detail pre-post-landslide air photo interpretation allowed for defining the deformation pattern occurred on the slope. For the Castelnuovo landslide, the triggering factors and the stability of the slope were evaluated with FLAC3D numerical modelling, in pre- and post-landslide conditions. Through this integrated analysis, the triggering factors, the landslide mechanism and the stability conditions of the landslides and the characterization of two main types of landslides affecting the piedmont hilly area of the Abruzzo region were investigated.

scholarly journals Tectonostratigraphy and major structures of the Georgian Greater Caucasus: Implications for structural architecture, along-strike continuity, and orogen evolution

Geosphere ◽  
2022 ◽  
Author(s):  
Charles C. Trexler ◽  
Eric Cowgill ◽  
Nathan A. Niemi ◽  
Dylan A. Vasey ◽  
Tea Godoladze
Keyword(s):  
Fault System ◽  
Thrust Faults ◽  
Geologic Mapping ◽  
Greater Caucasus ◽  
The Core ◽  
The North ◽  
Thrust Sheets ◽  
Southern Half ◽  
Caucasus Mountains ◽  
Structural Architecture

Although the Greater Caucasus Mountains have played a central role in absorbing late Cenozoic convergence between the Arabian and Eurasian plates, the orogenic architecture and the ways in which it accommodates modern shortening remain debated. Here, we addressed this problem using geologic mapping along two transects across the southern half of the western Greater Caucasus to reveal a suite of regionally coherent stratigraphic packages that are juxtaposed across a series of thrust faults, which we call the North Georgia fault system. From south to north within this system, stratigraphically repeated ~5–10-km-thick thrust sheets show systematically increasing bedding dip angles (<30° in the south to subvertical in the core of the range). Likewise, exhumation depth increases toward the core of the range, based on low-temperature thermochronologic data and metamorphic grade of exposed rocks. In contrast, active shortening in the modern system is accommodated, at least in part, by thrust faults along the southern margin of the orogen. Facilitated by the North Georgia fault system, the western Greater Caucasus Mountains broadly behave as an in-sequence, southward-propagating imbricate thrust fan, with older faults within the range progressively abandoned and new structures forming to accommodate shortening as the thrust propagates southward. We suggest that the single-fault-centric “Main Caucasus thrust” paradigm is no longer appropriate, as it is a system of faults, the North Georgia fault system, that dominates the architecture of the western Greater Caucasus Mountains.

Linking dynamic earthquake rupture to tsunami modeling for the Húsavík-Flatey transform fault system in North Iceland

2021 ◽  
Author(s):  
Fabian Kutschera ◽  
Sara Aniko Wirp ◽  
Bo Li ◽  
Alice-Agnes Gabriel ◽  
Benedikt Halldórsson ◽  
...  
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Fault System ◽  
Deformation Pattern ◽  
Tsunami Modeling ◽  
Earthquake Rupture ◽  
Worst Case ◽  
Fault Systems ◽  
Complex Fault ◽  
The Impact

<p>Earthquake generated tsunamis are generally associated with large submarine events on dip-slip faults, in particular on subduction zone megathrusts (Bilek and Lay, 2018). Submerged ruptures across strike-slip fault systems mostly produce minor vertical offset and hence no significant disturbance of the water column. For the 2018 Mw 7.5 Sulawesi earthquake in Indonesia, linked dynamic earthquake rupture and tsunami modeling implies that coseismic, mixed strike-slip and normal faulting induced seafloor displacements were a critical component generating an unexpected and devastating local tsunami in Palu Bay (Ulrich et al., 2019), with important implications for tsunami hazard assessment of submarine strike-slip fault systems in transtensional tectonic settings worldwide. </p><p>We reassess the tsunami potential of the ~100 km Húsavík Flatey Fault (HFF) in North Iceland using physics-based, linked earthquake-tsunami modelling. The HFF consists of multiple fault segments that localise both strike-slip and normal movements, agreeing with a transtensional deformation pattern (Garcia and Dhont, 2005). The HFF hosted several historical earthquakes with M>6. It crosses from off-shore to on-shore in immediate proximity to the town of Húsavík. We analyse simple and complex fault geometries and varying hypocenter locations accounting for newly inferred fault geometries (Einarsson et al., 2019), 3-D subsurface structure (Abril et al., 2020), bathymetry and topography of the area, primary stress orientations and the stress shape ratio constrained by the inversion of earthquake focal mechanisms (Ziegler et al., 2016).</p><p>Dynamic rupture models are simulated with SeisSol (https://github.com/SeisSol/SeisSol), a scientific open-source software for 3D dynamic earthquake rupture simulation (www.seissol.org, Pelties et al., 2014). SeisSol, a flagship code of the ChEESE project (https://cheese-coe.eu), enables us to explore simple and complex fault and subsurface geometries by using unstructured tetrahedral meshes. The dynamically adaptive, parallel software sam(oa)²-flash (https://gitlab.lrz.de/samoa/samoa) is used for tsunami propagation and inundation simulations and solves the hydrostatic shallow water equations (Meister, 2016). We consider the contribution of the horizontal ground deformation of realistic bathymetry to the vertical displacement following Tanioka and Satake, 1996. The tsunami simulations use time-dependent seafloor displacements to initialise bathymetry perturbations. </p><p>We show that up to 2 m of vertical coseismic offset can be generated during dynamic earthquake rupture scenarios across the HFF, which resemble historic magnitudes and are controlled by spontaneous fault interaction in terms of dynamic and static stress transfer and rupture jumping across the complex fault network. Our models reveal rake deviations from pure right-lateral strike-slip motion, indicating the presence of dip-slip components, in combination with large shallow fault slip (~8 m for a hypocenter in the East), which can cause a sizable tsunami affecting North Iceland. Sea surface height (ssh), which is defined as the deviation from the mean sea level, and inundation synthetics give an estimate about the impact of the tsunami along the coastline. We further investigate a physically plausible worst-case scenario of a tsunamigenic HFF event, accounting for tsunami sourcing mechanisms similar to the one causing the Sulawesi Tsunami in 2018.</p>

Beyond elasticity: Are Coulomb properties of the Earth’s crust important for volcano geodesy?

2021 ◽  
Author(s):  
Håvard Svanes Bertelsen ◽  
Frank Guldstrand ◽  
Sigmundsson Freysteinn ◽  
Rikke Pedersen ◽  
Karen Mair ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Numerical Models ◽  
Geodetic Data ◽  
Tensile Fracture ◽  
Dislocation Model ◽  
Deformation Pattern ◽  
Volcano Geodesy ◽  
Plumbing Systems ◽  
Deformation Patterns ◽  
Active Volcanoes

<p><span>Geodetic modelling has become an established procedure to interpret the dynamics of active volcanic plumbing systems. Most established geodetic models implemented for inverting geodetic data share similar physical assumptions: (1) the Earth's crust is modelled as an infinite, homogeneous elastic half-space with a flat surface, (2) there is no anisotropic horizontal stress to simulate tectonic stresses, (3) the source boundary conditions are kinematic, i.e., they account for an instantaneous inflation or deflation of the source. Field and geophysical observations, however, provide evidence that significant inelastic shear deformation of the host rock can accommodate the propagation of dykes and sills. We show that inelastic processes accommodating the emplacement of dykes in the brittle crust have large implications for dyke-induced surface deformation patterns. </span></p><p><span>We present two quantitative laboratory experiments that simulate two distinct dyke emplacement mechanisms, in agreement with geological and geophysical observations: (1) dyke propagation as a tensile fracture through a dominantly elastic host in gelatin, and (2) dyke propagation in the silica flour as viscous indenter, which pushes its ahead plastic host that dominantly fails in shear. The syn-emplacement surface deformation is monitored during each experiment. Each dyke emplacement mechanism triggers drastically distinct surface deformation patterns: two uplifting bulges separated by a trough in the gelatin experiment, in good agreement with the expected dyke-induced deformation predicted by the rectangular dislocation model, versus a single uplifting elongated bulge above the apex of the dyke in the silica flour experiment. This first-order difference shows that (1) the rheology of the host and the emplacement mechanisms of dykes are key factors for interpreting dyke-induced geodetic data at active volcanoes, and (2) static, kinematic geodetic models, such as the rectangular dislocation model, have limitations for revealing the physics and dynamics of volcanic plumbing systems. </span></p><p><span>There is no geodetic model associated with dyke emplacement able to reproduce the single uplifting bulge measured in our silica flour experiment. Instead, such surface deformation pattern is usually fitted with geodetic models of inflating spherical, ellipsoidal or horizontal planar sources. Our silica flour experiment thus shows that (1) a successful data fit is not sufficient and does not imply a physically relevant interpretation, and (2) dykes emplaced as viscous indenters should be considered as an alternative interpretation of single uplifting bulges measured at active volcanoes. This implies that novel geodetic models accounting for dykes emplaced as viscous indenters should be designed to interpret dyke-induced surface deformation patterns in favorable geological settings, e.g. felsic volcanoes. </span></p><p><span>In summary, our study motivates the design of new geodetic models that move beyond elasticity, i.e. that account for the realistic elasto-plastic mechanical behavior we know occurs in the Earth's brittle crust. In addition, it highlights the added value of our </span><span><em>laboratory volcano geodesy</em></span><span> approach, which can be the foundation for designing novel geodetic models that accounts for processes that cannot be implemented in numerical models. </span></p>

Integrated analysis of geophysical and geochemical data from cold fluid seepage system along the Gydratny Fault (Lake Baikal)

2020 ◽  
Author(s):  
Olesya Vidischeva ◽  
Marina Solovyeva ◽  
Evgeniya Egoshina ◽  
Yana Vasilevskaya ◽  
Elena Poludetkina ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Lake Baikal ◽  
Carbon Isotopic Composition ◽  
Fault System ◽  
Geochemical Data ◽  
Integrated Analysis ◽  
Fluid Migration ◽  
Carbon Isotopic ◽  
Lake Bottom ◽  
Methane Concentrations

<p>Lake Baikal is a part of large intracontinental rift zone. Baikal sedimentary infill is more than 7 km thick and was developed under predominantly extensional tectonics. Large number of faults of different geometry is imaged by several seismic surveys carried out in the region. The fault systems serve as fluid discharge pathways from deep sources to surface. A number of active seepage structures were mapped and studied during the Class@Baikal expeditions along the major fault system of the Central Baikal basin, which extends in SW-NE direction over 40 km and was named recently as the Gydratny Fault. Irregular distribution of these seeps, differences in their morphology and activity rate imply a variable permeability of the fault and different characteristics of migration pathways along its segments.</p><p>High-resolution seismic sections were acquired across the Gydratny Fault during the Class@Baikal cruises. The survey was followed by extensive bottom sediments and gases sampling. Hydrocarbon gases and isotopic characteristics as well as sediment pore water composition were analysed. Methane was detected in sediments along the whole fault extend in concentrations of more than 100 ml/l, exceeding background values (<15 ml/l), suggesting that the fault plane acts as regional fluid migration path. The highest methane content (>275 ml/l) and the presence of its homologues were observed at several local sites situated along the fault and associated with mud volcanoes and gas hydrate bearing seeps. The carbon isotopic composition varies from -72 to -57‰ VPDB for methane and from -21 to -31 ‰ VPDB for ethane, suggesting that these are thermogenic gases that migrate from deep layers of sedimentary infill of the basin.</p><p>Seismic data show well-established segmented nature of the Gydratny Fault system, which is believed to be a reason for observed variations of fluid discharge rates. Integrated analysis of the collected geophysical and geochemical data allowed evaluating contributions of different structural elements of the Gydratny Fault to fluid migration pattern in the area. NE segment of the fault system is a well expressed normal fault propagating to the lake bottom which is associated with higher methane concentrations (150-200 ml/l), elevated methane homologues content of up to 40 ml/l and heavier carbon isotopic composition in gas samples. The SW segments is either faintly expressed in the bottom relief or does not reach the surface at all. The methane concentrations in sediment samples collected from the segment are 100-150 ml/l and its carbon isotopic composition is normally lighter. We suggest that deeper parts of the SW fault segment are still highly conductive and concentrated hydrocarbon fluids migrate from the source upwards but some near-surface dispersal of migrated fluids occurs at places where the fault does not reach the lake bottom. The Gydratny master fault is accompanied by numerous subsidiary faults developed within hanging wall while footwall is less faulted. The associated faults are believed to enhance the main fluid migration system and this interpretation is supported by observations of normally higher methane concentrations in bottom sediments of the hanging block.</p><p>This study was funded by RFBR Grant № 18-35-00363.</p>

Multiphase rotational extension and marginal flexure along a developing passive margin: the Western Afar Margin, East Africa

2020 ◽  
Author(s):  
Frank Zwaan ◽  
Giacomo Corti ◽  
Derek Keir ◽  
Federico Sani ◽  
Ameha Muluneh ◽  
...  
Keyword(s):  
East Africa ◽  
Large Scale ◽  
Structural Evolution ◽  
Good Evidence ◽  
Passive Margin ◽  
Fault System ◽  
Afar Depression ◽  
Multidisciplinary Study ◽  
Structural Architecture ◽  
Echelon Fault

<p>This multidisciplinary study focuses on the tectonics of the Western Afar Margin (WAM), which is situated between the Ethiopian Plateau and Afar Depression in East Africa. The WAM represents a developing passive margin in a highly volcanic setting, thus offering unique opportunities for the study of rifting and (magma-rich) continental break-up, and our results have both regional and global implications.</p><p>Earthquake analysis shows that the margin is still deforming under a ca. E-W extension regime (a result also obtained by analysis on fault measurements from recent field campaigns), whereas Afar itself undergoes a more SW-NE extension. Together with GPS data, we see Afar currently opening in a rotational fashion. This opening is however a relatively recent and local phenomenon, due to the rotation of the Danakil microcontinent modifying the regional stress field (since 11 Ma). Regional tectonics is otherwise dominated by the rotation of Arabia since 25 Ma and should cause SW-NE (oblique) extension along the WAM. This oblique motion is indeed recorded in the large-scale en echelon fault patterns along the margin, which were reactivated in the current E-W extension regime. We thus have good evidence of a multiphase rotational history of the WAM and Afar.</p><p>Furthermore, analysis of the margin’s structural architecture reveals large-scale flexure towards Afar, likely representing the developing seaward-dipping reflectors that are typical for magma-rich margins. Detailed fault mapping and earthquake analysis show that recent faulting is dominantly antithetic (dipping away from the rift), bounding remarkable marginal grabens, although a large but older synthetic escarpment fault system is present as well. By means of analogue modelling efforts we find that marginal flexure indeed initially develops a large escarpment, whereas the currently active structures only form after significant flexure. Moreover, these models show that marginal grabens do not develop under oblique extension conditions. Instead, the latter model boundary conditions create the large-scale en echelon fault arrangement typical of the WAM. We derive that the recent structures of the margin could have developed only after a shift to local orthogonal extension. These modeling results support the multiphase extension scenario as described above.</p><p>Altogether, our findings are highly relevant for our understanding of the structural evolution of (magma-rich) passive margins. Indeed, seismic sections of such margins show very similar structures to those of the WAM. However, the general lack of marginal grabens, which are so obvious along the WAM, can be explained by the fact that most rift systems undergo or have undergone oblique extension, often in multiple phases during which structures from older phases control subsequent deformation.</p>

Active Deformation along the Southern End of the Tosco-Abreojos Fault System: New Insights from Multibeam Swath Bathymetry

2010 ◽  
Vol 168 (8-9) ◽  
pp. 1363-1372 ◽  
Author(s):  
François Michaud ◽  
Thierry Calmus ◽  
Gueorgui Ratzov ◽  
Jean-Yves Royer ◽  
Marc Sosson ◽  
...  
Keyword(s):  
Fault System ◽  
Active Deformation ◽  
Swath Bathymetry

Tectonics and sedimentation of the Lower and Middle Pleistocene mixed siliciclastic/bioclastic sedimentary successions of the Ionian Peloritani Mts (NE Sicily, Southern Italy): the onset of opening of the Messina Strait

2009 ◽  
Vol 1 (1) ◽  
Author(s):  
Agata Stefano ◽  
Sergio Longhitano
Keyword(s):  
Tectonic Setting ◽  
Fault System ◽  
Tectonic Activity ◽  
Middle Pleistocene ◽  
Central Mediterranean ◽  
Coastal Margin ◽  
Ne Sicily ◽  
Messina Strait ◽  
Block Faulting ◽  
Tectonics And Sedimentation

AbstractBiostratigraphic analyses carried out on siliciclastic/bioclastic deposits discontinuously cropping out along the Ionian flank of NE Sicily, indicate that they form two sedimentary events of Early and Middle Pleistocene, respec tively. Vertical facies successions, showing transgressive trends, suggest that sedimentation occurred within semi-enclosed marine embayments, where sublittoral coastal wedges developed on steep ramp-type shelves. Sediments accumulated in shoreface to offshore transitions along steep bottom profiles. This depositional scenario was strongly conditioned by the tectonic activity of the rift zone linking Western Calabria and Eastern Sicily. The effects of glacio-eustatism were also recognized. According to our reconstruction, the study area was controlled by a transfer fault system which affected the coastal margin producing major episodes of uplift and subsidence. Block-faulting was responsible for significant cannibalization and recycling of older deposits during the Middle Pleistocene. Such a tectonic setting can be considered the precursor scenario for the formation of the Messina Strait between Calabria and Sicily. This narrow, linear basin influences the hydrodynamic setting of sublittoral deposits along the Ionian coast of Sicily, giving rise to strong flood/ebb tidal currents. The uppermost part of the Middle Pleistocene succession recognized in the study area is indeed dominated by tide-influenced associations of sedimentary structures which most likely record the first stage of the opening of this ‘seaway’ of the central Mediterranean Sea.

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