Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

Anchuela, Óscar Pueyo; Lafuente, Paloma; Arlegui, L. E.; Liesa, Carlos L.; Simón, José Luis Múñoz de Baena y

doi:10.1007/s00531-015-1283-y

Cited by 19 publications

(7 citation statements)

References 36 publications

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“…Analog models also show that the upward propagation of thrust faults can be slowed down or even halted by the presence of pre-existing frictional discontinuity (e.g., decollements) above the fault propagating tip (Bonanno et al, 2017). However, they can also be determined by the relatively young inception of fault activity within the current regional stress state or by the interplay between fault activity and sedimentation rates in the cases in which the second one is significantly higher than the first one (Pueyo Anchuela et al, 2016). Blind thrusts are documented as to be the cause of several significant earthquakes and tsunami worldwide (Hauksson et al, 1995;Lettis et al, 1997;Borrero et al, 2001;Hayes et al, 2010;Burrato et al, 2012;McAuliffe et al, 2015) thus significantly contributing to seismic and tsunami hazard.…”

Section: Introductionmentioning

confidence: 97%

Probabilistic Assessment of Slip Rates and Their Variability Over Time of Offshore Buried Thrusts: A Case Study in the Northern Adriatic Sea

et al. 2021

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When sedimentation rates overtake tectonic rates, the detection of ongoing tectonic deformation signatures becomes particularly challenging. The Northern Apennines orogen is one such case where a thick Plio-Pleistocene foredeep sedimentary cover blankets the fold-and-thrust belt, straddling from onshore (Po Plain) to offshore (Adriatic Sea), leading to subtle or null topo-bathymetric expression of the buried structures. The seismic activity historically recorded in the region is moderate; nonetheless, seismic sequences nearing magnitude 6 punctuated the last century, and even some small tsunamis were reported in the coastal locations following the occurrence of offshore earthquakes. In this work, we tackled the problem of assessing the potential activity of buried thrusts by analyzing a rich dataset of 2D seismic reflection profiles and wells in a sector of the Northern Apennines chain located in the near-offshore of the Adriatic Sea. This analysis enabled us to reconstruct the 3D geometry of eleven buried thrusts. We then documented the last 4 Myr slip history of four of such thrusts intersected by two high-quality regional cross-sections that were depth converted and restored. Based on eight stratigraphic horizons with well-constrained age determinations (Zanclean to Middle Pleistocene), we determined the slip and slip rates necessary to recover the observed horizon deformation. The slip rates are presented through probability density functions that consider the uncertainties derived from the horizon ages and the restoration process. Our results show that the thrust activation proceeds from the inner to the outer position in the chain. The slip history reveals an exponential reduction over time, implying decelerating slip-rates spanning three orders of magnitudes (from a few millimeters to a few hundredths of millimeters per year) with a major slip-rate change around 1.5 Ma. In agreement with previous works, these findings confirm the slip rate deceleration as a widespread behavior of the Northern Apennines thrust faults.

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Section: Introductionmentioning

confidence: 97%

Probabilistic Assessment of Slip Rates and Their Variability Over Time of Offshore Buried Thrusts: A Case Study in the Northern Adriatic Sea

et al. 2021

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“…These studies have shown geophysical images of faulting, supporting and/or extending observations on outcrops, boreholes, and trench data and contributed to base knowledge of seismogenic structures as well as to the seismic hazard assessment of several regions around the world. Among the pioneers, we can mention Benson (1995), Smith and Jol (1995), Busby and Merritt (1999), Cai et al (1996), andLiner andLiner (1997), and in the successive 20 years, other 2D GPR studies were achieved across several faults worldwide (Audru et al, 2001;Demanet et al, 2001;Overgaard and Jakobsen, 2001;Bano et al, 2002;Liberty et al, 2003;Reiss et al, 2003;Slater and Niemi, 2003;Malik et al, 2007;Wallace et al, 2010;Yalciner et al, 2013;Imposa et al, 2015;Anchuela et al, 2016;Nobes et al, 2016;Matos et al, 2017;Pousse-Beltran et al, 2018;Zajc et al, 2018;Zhang et al, 2019 andShaikh et al, 2020). In Italy, only a few GPR studies are currently available across normal faults (e.g., Salvi et al, 2003;Jewell and Bristow, 2006;Pauselli et al, 2010;Roberts et al, 2010;Ercoli et al, 2013aErcoli et al, , 2014Bubeck et al, 2015;Cinti et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

Ground-penetrating radar signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

et al. 2021

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Abstract. With the aim of unveiling evidence of Late Quaternary faulting, a series of ground-penetrating radar (GPR) profiles were acquired across the southern portion of the Fosso della Valle–Campotenese normal fault (VCT), located at the Campotenese continental basin (Mt. Pollino region) in the southern Apennines active extensional belt (Italy). A set of 49 GPR profiles, traced nearly perpendicular to this normal fault, was acquired using 300 and 500 MHz antennas and carefully processed through a customized workflow. The data interpretation allowed us to reconstruct a pseudo-3D model depicting the boundary between the Mesozoic bedrock and the sedimentary fill of the basin, which were in close proximity to the fault. Once the GPR signature of faulting was reviewed and defined, we interpret near-surface alluvial and colluvial sediments dislocated by a set of conjugate (W- and E-dipping) discontinuities that penetrate inside the underlying Triassic dolostones. Close to the contact between the continental deposits and the bedrock, some buried scarps which offset wedge-shaped deposits are interpreted as coseismic ruptures, subsequently sealed by later deposits. Our pseudo-3D GPR dataset represented a good trade-off between a dense 3D-GPR volume and conventional 2D data, which normally requires a higher degree of subjectivity during the interpretation. We have thus reconstructed a reliable subsurface fault pattern, discriminating master faults and a series of secondary splays. This contribution better characterizes active Quaternary faults in an area which falls within the Pollino seismic gap and is considered prone to severe surface faulting. Our results encourage further research at the study site, whilst we also recommend our workflow for similar regions characterized by high seismic hazard and scarcity of near-surface geophysical data.

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“…These studies have shown geophysical images of faulting, supporting and/or extending outcrop, borehole, trench data, and contributing to base-knowledge of seismogenic structures as well as to the seismic hazard assessment of several regions around the world. Among the pioneers, we can mention Benson (1995), Smith and Jol (1995), Busby and Merritt (1999), Cai et al (1996) and Liner and Liner (1997), and on the successive twenty years, other 2D GPR studies were achieved across several faults (Audru et al 2001;Demanet et al 2001;Overgaard and Jakobsen, 2001;Bano et al 2002;Liberty et al 2003;Reiss et al 2003;Slater and Niemi, 2003;Malik et al 2007;Wallace et al 2010;Yalciner et al 2013;Imposa et al 2015;Anchuela et al 2016;Nobes et al 2016;Matos et al 2017;Pousse-Beltran et al 2018;Zajc et al 2018;Zhang et al 2019 andShaikh et al 2020). A few GPR surveys have been acquired across Italian normal faults (Salvi et al 2003;Jewell and Bristow, 2006;Pauselli et al 2010;Roberts et al 2010;Ercoli et al 2013a;Bubeck et al 2015;Cinti et al 2015).…”

Section: Methodsmentioning

confidence: 99%

GPR signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

Ercoli

Cirillo

Pauselli

et al. 2021

Preprint

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Abstract. With the aim of unveiling evidence of Late Quaternary faulting, a series of Ground Penetrating Radar (GPR) profiles were acquired across the Campotenese continental basin (Mt. Pollino region) in the southern Apennines active extensional belt (Italy). A set of forty-nine 300 MHz and 500 MHz GPR profiles, traced nearly perpendicular to a buried normal fault, were acquired and carefully processed through a customized workflow. The data interpretation allowed us to reconstruct a pseudo-3D model depicting the boundary between the Mesozoic bedrock and the sedimentary fill of the basin, which were in close proximity to the fault. Once reviewing and defining the GPR signature of faulting, we highlight in our data how near surface alluvial and colluvial sediments appear to be dislocated by a set of conjugate (west and east-dipping) discontinuities that penetrate inside the underlying Triassic dolostones. Close to the contact between the continental deposits and the bedrock, some buried scarps which offset wedge-shaped deposits are interpreted as coseismic ruptures, subsequently sealed by later deposits. Although the use of pseudo-3D GPR data implies more complexity linking the geophysical features among the radar images, we have reconstructed a reliable subsurface fault pattern, discriminating master faults and a series of secondary splays. We believe our contribution provides an improvement in the characterization of active faults in the study area which falls within the Pollino seismic gap and is considered potentially prone to severe surface faulting. Our aim is for our approach and workflow to be of inspiration for further studies in the region as well as for similar high seismic hazard areas characterized by scarcity of near-surface data.

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Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

Cited by 19 publications

References 36 publications

Probabilistic Assessment of Slip Rates and Their Variability Over Time of Offshore Buried Thrusts: A Case Study in the Northern Adriatic Sea

Probabilistic Assessment of Slip Rates and Their Variability Over Time of Offshore Buried Thrusts: A Case Study in the Northern Adriatic Sea

Ground-penetrating radar signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

GPR signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

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