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Papers by Antonio Cattaneo

Research paper thumbnail of Morphology, distribution and origin of recent submarine landslides of the Ligurian Margin (North-western Mediterranean): some insights into geohazard assessment

Marine Geophysical Researches, 2011

Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, ... more Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 108 m3 in volume: Type 1), deep scars 100–500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are located in different environmental contexts of the margin, including the deep Var Sedimentary Ridge (VSR) and the upper part of the continental slope in the Gulf of Genova (Finale Slide and Portofino Slide), with volumes of missing sediment reaching up to 1.5 × 109 m3. High sedimentation rates related to hyperpycnal flows, faults and earthquake activity, together with sea-level fluctuations are the main factors invoked to explain the distribution and sizes of these different failure types.

Research paper thumbnail of Tectonic inheritance and Pliocene-Pleistocene inversion of the Algerian margin around Algiers: Insights from multibeam and seismic reflection data

Research paper thumbnail of Comment on “Zemmouri earthquake rupture zone ( M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model” by A. Ayadi et al

Journal of Geophysical Research, 2010

Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation ... more Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model" by A. Ayadi et al. Citation: Déverchère, J., B. Mercier de Lépinay, A. Cattaneo, P. Strzerzynski, E. Calais, A. Domzig, and R. Bracene (2010), Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model" by A. Ayadi et al.,

Research paper thumbnail of Sedimentary structures offshore Ortona, Adriatic Sea — Deformation or sediment waves

Research paper thumbnail of 26th December 2004 great Sumatra–Andaman earthquake: Coseismic and post-seismic motions in northern Sumatra

Earth and Planetary Science Letters, 2007

Research paper thumbnail of A review of undulated sediment features on Mediterranean prodeltas: distinguishing sediment transport structures from sediment deformation

Marine Geophysical Researches, 2010

Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene w... more Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and hydrodynamic time series and hydrographic transects. In this study we show that the characteristics of the sediment undulations (configuration of the reflections down section and between adjacent undulations and overall morphologic characteristics) are incompatible with a genesis by sediment deformation alone and do not show evidence of sediment deformation in most cases. Various processes in the benthic boundary layer can be invoked to explain the variety of features observed in the numerous areas displaying sediment undulations.

Research paper thumbnail of Evidence of soft sediment deformation, fluid escape, sediment failure and regional weak layers within the late Quaternary mud deposits of the Adriatic Sea

Marine Geology, 2004

The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow ... more The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow subsurface sediment mobilization. Amplitude blanking in high-resolution seismic data and limited sediment core information document that free gas is diffused at very shallow stratigraphic levels; pockmarks and blow-out pipes indicate expulsion of overpressured fluid; possible polygonal fault systems denote areas of sediment contraction and dewatering. Core data and VHR seismic profiles suggest that very high accumulation rates of homogeneous and fine-grained deposits result in fluid accumulation (high pore water pressure) within low-permeability sediments. The fluid flow processes that are active under such regime are still poorly understood. Enhanced accumulation rates during particular intervals can potentially result in trapping of fluids leading to increased pore pressure and decreased shear strength. Seismicity is high in the study area, and recurrent earthquakes or tsunamis provide an effective mechanism leading to the cyclic loading of sediment, favoring mobilization of gas-charged sediments.

Research paper thumbnail of The late-Holocene Gargano subaqueous delta, Adriatic shelf: Sediment pathways and supply fluctuations

Marine Geology, 2003

The Gargano subaqueous delta formed on the eastern and southeastern sides of the Gargano promonto... more The Gargano subaqueous delta formed on the eastern and southeastern sides of the Gargano promontory, in the western Adriatic. This subaqueous deposit represents the southernmost portion of the late-Holocene highstand systems tract (HST) growing along the western side of the Adriatic as an extensive wedge of deltaic and shallowmarine mud. The late-Holocene HST rests above a regional downlap surface that marks the time of maximum landward shift of the shoreline attained around 5.5 cal. kyr BP, at the end of the late-Pleistocene^Holocene sea-level rise. High-resolution seismic^stratigraphic and tephra correlation indicate the presence of a thin basal unit recording condensed deposition between 5.5 and 3.7 cal. kyr BP over much of the basin. Above this unit, sediment accumulation rates increased to high values (as much as 1.5 cm yr 31 ) reflecting the stabilisation of relative sea level and the forcing from high frequency climatic or anthropogenic changes affecting river dynamics. The late-Holocene mud wedge, of which the Gargano subaqueous delta is a significant component, reaches up to 35 m in thickness and has a volume of ca 180 km 3 . The shore-parallel thickness distribution of the mud wedge reflects the dominant oceanographic regime of the basin and the asymmetric location of the mostly western sediment sources (with a combined modern delivery of 51.7U10 6 t yr 31 of mean suspended load). In sections perpendicular to the coast the late-Holocene mud wedge appears composed of forestepping clinoforms with gently dipping foresets (typically 0.5 ‡). The Gargano subaqueous delta is characterised by a submarine topset in water depths shallower than 25^28 m, and accounts for about 1/7th of the total volume of the late-Holocene mud wedge, despite the absence of direct river supply to the Gargano area. In the area of maximum interaction between shore-parallel currents and basin morphology, progradation occurs onto a flat and barren bedrock outcrop in about 50^80 m water depth. The rapid transition from a thickness of 30 m of late-Holocene mud to nil is a good indication of the role of southward-flowing bottom-hugging shelf currents in causing the redistribution of sediment along the Adriatic inner shelf. Additional evidence of this regime comes from: (1) the most recent sigmoid (defined at seismic^stratigraphic scale) deposited since the onset of the Little Ice Age, showing a shore-parallel thickness distribution and a main depocentre to the southeast of the Gargano promontory; (2) the maximum values of sediment accumulation rates over the last century (documented by 210 Pb measurements) defining a narrow shore-parallel belt immediately seaward of the depocentre of the most recent sigmoid. The Gargano subaqueous delta grows from the outbuilding of progressively younger progradational sigmoids that tend to parallel the previous ones. The Gargano subaqueous delta differs from other documented late-Holocene subaqueous deltas 0025-3227 / 02 / $^see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 5 -3 2 2 7 ( 0 2 ) 0 0 6 1 4 -X Marine Geology 193 www.elsevier.com/locate/margeo because its growth reflects: (1) sediment transport dominated by bottom currents sub-parallel to the strike of the composing clinoforms; (2) a complex supply regime including the Po delta (350 km to the north) and several coalescing Apennine rivers acting as 'line source'; (3) several alternating intervals of enhanced outbuilding and condensed deposition; and (4) an in-phase growth of the most recent sigmoid with the major progradation of the Po delta during the Little Ice Age. ß

Research paper thumbnail of Recent and active deformation pattern off the easternmost Algerian margin, Western Mediterranean Sea: New evidence for contractional tectonic reactivation

Marine Geology, 2009

We describe for the first time a set of large active thrusts and folds near the foot of the easte... more We describe for the first time a set of large active thrusts and folds near the foot of the easternmost Algerian margin, Western Mediterranean, from swath bathymetry and high-resolution seismic data acquired in 2005 during the Maradja2/Samra cruise. This active system resumes a previous passive margin and creates growth strata deposition on the limbs of large folds, resulting in the development of perched basins at the foot of the margin since less than~1 Ma. They form a set of overlapping fault segments verging toward the Algerian basin, in a way similar to what has been observed off eastern Algiers on the rupture zone of the 2003 Mw 6.8 Boumerdes earthquake. The horizontal shortening rate across large folds is estimated to be of the order of 1 mm/yr. Although no historical earthquakes are reported here, these fault segments could have been responsible for large (M~7.5) events in the past. This young tectonic system further supports the hypothesis of subduction inception of the Neogene oceanic lithosphere in the context of the Africa-Eurasia convergence.

Research paper thumbnail of Sedimentary response to climate and sea level changes during the past ~400 ka from borehole PRAD1-2 (Adriatic margin

Geochemistry Geophysics Geosystems, 2008

Research paper thumbnail of The Western Adriatic shelf clinoform: energy-limited bottomset

Continental Shelf Research, 2007

Research paper thumbnail of Seafloor undulation pattern on the Adriatic shelf and comparison to deep-water sediment waves

Marine Geology, 2004

The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow ... more The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow subsurface sediment mobilization. Amplitude blanking in high-resolution seismic data and limited sediment core information document that free gas is diffused at very shallow stratigraphic levels; pockmarks and blow-out pipes indicate expulsion of overpressured fluid; possible polygonal fault systems denote areas of sediment contraction and dewatering. Core data and VHR seismic profiles suggest that very high accumulation rates of homogeneous and fine-grained deposits result in fluid accumulation (high pore water pressure) within low-permeability sediments. The fluid flow processes that are active under such regime are still poorly understood. Enhanced accumulation rates during particular intervals can potentially result in trapping of fluids leading to increased pore pressure and decreased shear strength. Seismicity is high in the study area, and recurrent earthquakes or tsunamis provide an effective mechanism leading to the cyclic loading of sediment, favoring mobilization of gas-charged sediments.

Research paper thumbnail of The modern Po Delta system: Lobe switching and asymmetric prodelta growth

Marine Geology, 2005

The modern Po Delta system, comprising five main delta lobes, has been investigated by integratin... more The modern Po Delta system, comprising five main delta lobes, has been investigated by integrating VHR seismic surveys, recorded offshore from water depths as shallow as 5 m to the toe of the prodelta in about 30 m, with accurate historical cartography extending back several centuries. Previous studies give sedimentological and geochronological information from precisely positioned sediment cores. This combined historical and stratigraphic reconstruction of the modern Po prodelta allows volumetric reconstructions indicating an average sediment load of 9.4 10 6 t yr À 1 for Po di Pila and Po di Goro-Gnocca lobes. This estimate is remarkably consistent with the total sediment load of 11.5 10 6 t yr À 1 available for parts of the last century from a gauge station at the apex of the delta plain (in Pontelagoscuro).

Research paper thumbnail of Deep sea in situ excess pore pressure and sediment deformation off NW Sumatra and its relation with the December 26, 2004 Great Sumatra-Andaman Earthquake

International Journal of Earth Sciences, 2009

The swath bathymetric data acquired during the "Sumatra Aftershocks" cruise from the Sunda trench... more The swath bathymetric data acquired during the "Sumatra Aftershocks" cruise from the Sunda trench in the Indian Ocean to the north of the Sumatra Island imaged several scars and deposits. In situ pore pressure measurements using the Ifremer piezometer and coring demonstrate that high excess pore pressure and sediment deformation was generated by a recent event in the scar of the slope failure zone identified by J.T. Henstock and co-authors. This excess pore pressure is localized in the upper sedimentary layers and is not related to an interplate subduction process. Numerical simulations of the hydrological system that take into account the hydro-mechanical properties of the upper sediment layer show that the excess pore pressure and sediment deformations could be generated at the time of the December 26, 2004 Great Sumatra Earthquake.

Research paper thumbnail of Coseismic and post-seismic motions in northern Sumatra

Research paper thumbnail of Sedimentary structures offshore Ortona, Adriatic Sea — Deformation or sediment waves

Marine Geology, 2006

The late Holocene mud wedge on the Adriatic shelf offshore Ortona, Italy, shows undulating sub-pa... more The late Holocene mud wedge on the Adriatic shelf offshore Ortona, Italy, shows undulating sub-parallel seismic reflector sequences which extend several kilometres along strike and 100-200 m down-dip in water depth between 20 and 80 m. The amplitude of such undulations is up to 5 m and the undulations continue as stacked sediment packages downwards throughout the 35 m thick mud wedge. The undulations are separated by 4°to 5°dipping boundary zones and at first glance these sediment undulations resemble the seafloor sedimentary structures visible in the Humboldt Feature offshore California. There is an ongoing debate whether seafloor undulations are the result of deformation processes or sediment deposition and/or reworking due to submarine shelf currents. A dense net of recently reprocessed and digitally interpreted high-resolution Chirp seismic data on the Adriatic shelf favours an interpretation that these undulations developed, in the upper part of the stratigraphic section through sediment reworking rather than through deformation. There are three lines of evidence for this: (1) the spatial extent of the undulations coincides with higher seabed reflector amplitudes than found both on the shelf and in the distal part of the shelf. If the features were solely caused by slope failure there should be no change of amplitudes, (2) the seabed reflector amplitude is generally higher on the gently dipping or flat upslope limbs than on the steeper downslope limbs, supporting a current origin that causes preferred deposition of sediments with higher acoustic impedance on the top, (3) the boundaries between the undulations are dipping at angles that are much lower than the angle of internal friction of these sediments excluding that a simple model like the Mohr-Coulomb under gravitational loading could describe the undulations as sediment deformation and failures.

Research paper thumbnail of A geomechanical approach for the genesis of sediment undulations on the Adriatic shelf

Geochemistry Geophysics Geosystems, 2008

This study is among the first to examine the genesis of the seafloor and subsurface undulations o... more This study is among the first to examine the genesis of the seafloor and subsurface undulations on the Adriatic continental shelf by integrating stratigraphic information and in situ and laboratory geotechnical measurements. Interpretation of sediment behavior is based on a 32-m-long borehole crossing (1) a possible shear plane and (2) a silty clay layer at about 20 m below seafloor (mbsf) on which sediment undulations are rooted and could be interpreted as a potential weak layer succession. Our main results in terms of triggering mechanism for the observed undulations show that under an earthquake, liquefaction and/or failure of the silty-clay sediments (weak layer) leading to deformation of the upper more cohesive sediments is possible only when such a layer is buried by less than 5 m. For greater burial thicknesses, this silty clay becomes stable under the confining lithostatic pressure exerted by the overlying sediment. This work shows that the seafloor and subsurface undulations observed in the study area are most probably the result of an early deformation process of the seafloor followed by a depositional process.

Research paper thumbnail of 26th December 2004 great Sumatra–Andaman earthquake: Coseismic and post-seismic motions in northern Sumatra

Earth and Planetary Science Letters, 2007

Trench-parallel thrust faults verging both landward and seaward were mapped in the portion of wed... more Trench-parallel thrust faults verging both landward and seaward were mapped in the portion of wedge located between northern Sumatra and the Indian-Indonesian boundary. The spatial aftershocks distribution of the 26th December 2004 earthquake shows that the post-seismic motion is partitioned along two thrust faults, the Lower and Median Thrust Faults, the latter being right-laterally offset by a N-S lower plate fracture zone located along the 93.6°N meridian. Between February 2005 and August 2005, the upper plate aftershock activity shifted from southeast of this fracture zone to northwest of it, suggesting that the lower plate left-lateral motion along the fracture zone may have induced a shift of the upper plate post-seismic activity along the Median Thrust Fault. Based on swath bathymetric and 3.5 kHz data, co-seismic deformations were weak close to the trench. Joint seismic-geodetic determination of slip distribution and time arrivals and heights of tsunami waves suggest that the coseismic slip was maximum along a portion of the Upper Thrust Fault located north of the Tuba Ridge, suggesting that the Upper Thrust Fault might be a splay fault originated at the interplate fault plane. As the Upper Thrust Fault is steeper than the slab, the vertical motion of the adjacent Outer Arc and overlying water is much larger compared to the one resulting from slip on the megathrust alone, increasing tsunamogenic effects.

Research paper thumbnail of A review of undulated sediment features on Mediterranean prodeltas: distinguishing sediment transport structures from sediment deformation

Marine Geophysical Researches, 2010

Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene w... more Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and hydrodynamic time series and hydrographic transects. In this study we show that the characteristics of the sediment undulations (configuration of the reflections down section and between adjacent undulations and overall morphologic characteristics) are incompatible with a genesis by sediment deformation alone and do not show evidence of sediment deformation in most cases. Various processes in the benthic boundary layer can be invoked to explain the variety of features observed in the numerous areas displaying sediment undulations.

Research paper thumbnail of Coastal dynamics under conditions of rapid sea-level rise: Late Pleistocene to Early Holocene evolution of barrier–lagoon systems on the northern Adriatic shelf (Italy

Quaternary Science Reviews, 2008

This multidisciplinary case study of two preserved barrier systems combined the analysis of radio... more This multidisciplinary case study of two preserved barrier systems combined the analysis of radiocarbon datings, grain-size distributions, high-resolution seismics, and shelf bathymetry with reconstructions of palaeo-environmental conditions (tides, waves, sea-level change) and forward modelling of barrier-lagoon systems, to provide an integrated view of the coastal transgressive evolution of a large sector of the northern Adriatic shelf between 15 and 8 ka BP. Palaeoenvironmental reconstructions point to increased tidal amplitude, low-energy wave climate and high rates of sea-level rise (up to 60 mm/a) during the formation of the oldest preserved barrier system (not, vert, similar90 m water depth; 14.3 cal ka BP). A younger barrier system (42 m water depth; 10.5 cal ka BP) formed under conditions of lower tidal amplitude, higher wave energy and a lower rate of sealevel rise (10 mm/a).

Research paper thumbnail of Morphology, distribution and origin of recent submarine landslides of the Ligurian Margin (North-western Mediterranean): some insights into geohazard assessment

Marine Geophysical Researches, 2011

Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, ... more Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 108 m3 in volume: Type 1), deep scars 100–500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are located in different environmental contexts of the margin, including the deep Var Sedimentary Ridge (VSR) and the upper part of the continental slope in the Gulf of Genova (Finale Slide and Portofino Slide), with volumes of missing sediment reaching up to 1.5 × 109 m3. High sedimentation rates related to hyperpycnal flows, faults and earthquake activity, together with sea-level fluctuations are the main factors invoked to explain the distribution and sizes of these different failure types.

Research paper thumbnail of Tectonic inheritance and Pliocene-Pleistocene inversion of the Algerian margin around Algiers: Insights from multibeam and seismic reflection data

Research paper thumbnail of Comment on “Zemmouri earthquake rupture zone ( M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model” by A. Ayadi et al

Journal of Geophysical Research, 2010

Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation ... more Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model" by A. Ayadi et al. Citation: Déverchère, J., B. Mercier de Lépinay, A. Cattaneo, P. Strzerzynski, E. Calais, A. Domzig, and R. Bracene (2010), Comment on "Zemmouri earthquake rupture zone (M w 6.8, Algeria): Aftershocks sequence relocation and 3D velocity model" by A. Ayadi et al.,

Research paper thumbnail of Sedimentary structures offshore Ortona, Adriatic Sea — Deformation or sediment waves

Research paper thumbnail of 26th December 2004 great Sumatra–Andaman earthquake: Coseismic and post-seismic motions in northern Sumatra

Earth and Planetary Science Letters, 2007

Research paper thumbnail of A review of undulated sediment features on Mediterranean prodeltas: distinguishing sediment transport structures from sediment deformation

Marine Geophysical Researches, 2010

Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene w... more Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and hydrodynamic time series and hydrographic transects. In this study we show that the characteristics of the sediment undulations (configuration of the reflections down section and between adjacent undulations and overall morphologic characteristics) are incompatible with a genesis by sediment deformation alone and do not show evidence of sediment deformation in most cases. Various processes in the benthic boundary layer can be invoked to explain the variety of features observed in the numerous areas displaying sediment undulations.

Research paper thumbnail of Evidence of soft sediment deformation, fluid escape, sediment failure and regional weak layers within the late Quaternary mud deposits of the Adriatic Sea

Marine Geology, 2004

The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow ... more The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow subsurface sediment mobilization. Amplitude blanking in high-resolution seismic data and limited sediment core information document that free gas is diffused at very shallow stratigraphic levels; pockmarks and blow-out pipes indicate expulsion of overpressured fluid; possible polygonal fault systems denote areas of sediment contraction and dewatering. Core data and VHR seismic profiles suggest that very high accumulation rates of homogeneous and fine-grained deposits result in fluid accumulation (high pore water pressure) within low-permeability sediments. The fluid flow processes that are active under such regime are still poorly understood. Enhanced accumulation rates during particular intervals can potentially result in trapping of fluids leading to increased pore pressure and decreased shear strength. Seismicity is high in the study area, and recurrent earthquakes or tsunamis provide an effective mechanism leading to the cyclic loading of sediment, favoring mobilization of gas-charged sediments.

Research paper thumbnail of The late-Holocene Gargano subaqueous delta, Adriatic shelf: Sediment pathways and supply fluctuations

Marine Geology, 2003

The Gargano subaqueous delta formed on the eastern and southeastern sides of the Gargano promonto... more The Gargano subaqueous delta formed on the eastern and southeastern sides of the Gargano promontory, in the western Adriatic. This subaqueous deposit represents the southernmost portion of the late-Holocene highstand systems tract (HST) growing along the western side of the Adriatic as an extensive wedge of deltaic and shallowmarine mud. The late-Holocene HST rests above a regional downlap surface that marks the time of maximum landward shift of the shoreline attained around 5.5 cal. kyr BP, at the end of the late-Pleistocene^Holocene sea-level rise. High-resolution seismic^stratigraphic and tephra correlation indicate the presence of a thin basal unit recording condensed deposition between 5.5 and 3.7 cal. kyr BP over much of the basin. Above this unit, sediment accumulation rates increased to high values (as much as 1.5 cm yr 31 ) reflecting the stabilisation of relative sea level and the forcing from high frequency climatic or anthropogenic changes affecting river dynamics. The late-Holocene mud wedge, of which the Gargano subaqueous delta is a significant component, reaches up to 35 m in thickness and has a volume of ca 180 km 3 . The shore-parallel thickness distribution of the mud wedge reflects the dominant oceanographic regime of the basin and the asymmetric location of the mostly western sediment sources (with a combined modern delivery of 51.7U10 6 t yr 31 of mean suspended load). In sections perpendicular to the coast the late-Holocene mud wedge appears composed of forestepping clinoforms with gently dipping foresets (typically 0.5 ‡). The Gargano subaqueous delta is characterised by a submarine topset in water depths shallower than 25^28 m, and accounts for about 1/7th of the total volume of the late-Holocene mud wedge, despite the absence of direct river supply to the Gargano area. In the area of maximum interaction between shore-parallel currents and basin morphology, progradation occurs onto a flat and barren bedrock outcrop in about 50^80 m water depth. The rapid transition from a thickness of 30 m of late-Holocene mud to nil is a good indication of the role of southward-flowing bottom-hugging shelf currents in causing the redistribution of sediment along the Adriatic inner shelf. Additional evidence of this regime comes from: (1) the most recent sigmoid (defined at seismic^stratigraphic scale) deposited since the onset of the Little Ice Age, showing a shore-parallel thickness distribution and a main depocentre to the southeast of the Gargano promontory; (2) the maximum values of sediment accumulation rates over the last century (documented by 210 Pb measurements) defining a narrow shore-parallel belt immediately seaward of the depocentre of the most recent sigmoid. The Gargano subaqueous delta grows from the outbuilding of progressively younger progradational sigmoids that tend to parallel the previous ones. The Gargano subaqueous delta differs from other documented late-Holocene subaqueous deltas 0025-3227 / 02 / $^see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 5 -3 2 2 7 ( 0 2 ) 0 0 6 1 4 -X Marine Geology 193 www.elsevier.com/locate/margeo because its growth reflects: (1) sediment transport dominated by bottom currents sub-parallel to the strike of the composing clinoforms; (2) a complex supply regime including the Po delta (350 km to the north) and several coalescing Apennine rivers acting as 'line source'; (3) several alternating intervals of enhanced outbuilding and condensed deposition; and (4) an in-phase growth of the most recent sigmoid with the major progradation of the Po delta during the Little Ice Age. ß

Research paper thumbnail of Recent and active deformation pattern off the easternmost Algerian margin, Western Mediterranean Sea: New evidence for contractional tectonic reactivation

Marine Geology, 2009

We describe for the first time a set of large active thrusts and folds near the foot of the easte... more We describe for the first time a set of large active thrusts and folds near the foot of the easternmost Algerian margin, Western Mediterranean, from swath bathymetry and high-resolution seismic data acquired in 2005 during the Maradja2/Samra cruise. This active system resumes a previous passive margin and creates growth strata deposition on the limbs of large folds, resulting in the development of perched basins at the foot of the margin since less than~1 Ma. They form a set of overlapping fault segments verging toward the Algerian basin, in a way similar to what has been observed off eastern Algiers on the rupture zone of the 2003 Mw 6.8 Boumerdes earthquake. The horizontal shortening rate across large folds is estimated to be of the order of 1 mm/yr. Although no historical earthquakes are reported here, these fault segments could have been responsible for large (M~7.5) events in the past. This young tectonic system further supports the hypothesis of subduction inception of the Neogene oceanic lithosphere in the context of the Africa-Eurasia convergence.

Research paper thumbnail of Sedimentary response to climate and sea level changes during the past ~400 ka from borehole PRAD1-2 (Adriatic margin

Geochemistry Geophysics Geosystems, 2008

Research paper thumbnail of The Western Adriatic shelf clinoform: energy-limited bottomset

Continental Shelf Research, 2007

Research paper thumbnail of Seafloor undulation pattern on the Adriatic shelf and comparison to deep-water sediment waves

Marine Geology, 2004

The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow ... more The late Quaternary sediments of the Adriatic Sea show clear evidence for fluid flow and shallow subsurface sediment mobilization. Amplitude blanking in high-resolution seismic data and limited sediment core information document that free gas is diffused at very shallow stratigraphic levels; pockmarks and blow-out pipes indicate expulsion of overpressured fluid; possible polygonal fault systems denote areas of sediment contraction and dewatering. Core data and VHR seismic profiles suggest that very high accumulation rates of homogeneous and fine-grained deposits result in fluid accumulation (high pore water pressure) within low-permeability sediments. The fluid flow processes that are active under such regime are still poorly understood. Enhanced accumulation rates during particular intervals can potentially result in trapping of fluids leading to increased pore pressure and decreased shear strength. Seismicity is high in the study area, and recurrent earthquakes or tsunamis provide an effective mechanism leading to the cyclic loading of sediment, favoring mobilization of gas-charged sediments.

Research paper thumbnail of The modern Po Delta system: Lobe switching and asymmetric prodelta growth

Marine Geology, 2005

The modern Po Delta system, comprising five main delta lobes, has been investigated by integratin... more The modern Po Delta system, comprising five main delta lobes, has been investigated by integrating VHR seismic surveys, recorded offshore from water depths as shallow as 5 m to the toe of the prodelta in about 30 m, with accurate historical cartography extending back several centuries. Previous studies give sedimentological and geochronological information from precisely positioned sediment cores. This combined historical and stratigraphic reconstruction of the modern Po prodelta allows volumetric reconstructions indicating an average sediment load of 9.4 10 6 t yr À 1 for Po di Pila and Po di Goro-Gnocca lobes. This estimate is remarkably consistent with the total sediment load of 11.5 10 6 t yr À 1 available for parts of the last century from a gauge station at the apex of the delta plain (in Pontelagoscuro).

Research paper thumbnail of Deep sea in situ excess pore pressure and sediment deformation off NW Sumatra and its relation with the December 26, 2004 Great Sumatra-Andaman Earthquake

International Journal of Earth Sciences, 2009

The swath bathymetric data acquired during the "Sumatra Aftershocks" cruise from the Sunda trench... more The swath bathymetric data acquired during the "Sumatra Aftershocks" cruise from the Sunda trench in the Indian Ocean to the north of the Sumatra Island imaged several scars and deposits. In situ pore pressure measurements using the Ifremer piezometer and coring demonstrate that high excess pore pressure and sediment deformation was generated by a recent event in the scar of the slope failure zone identified by J.T. Henstock and co-authors. This excess pore pressure is localized in the upper sedimentary layers and is not related to an interplate subduction process. Numerical simulations of the hydrological system that take into account the hydro-mechanical properties of the upper sediment layer show that the excess pore pressure and sediment deformations could be generated at the time of the December 26, 2004 Great Sumatra Earthquake.

Research paper thumbnail of Coseismic and post-seismic motions in northern Sumatra

Research paper thumbnail of Sedimentary structures offshore Ortona, Adriatic Sea — Deformation or sediment waves

Marine Geology, 2006

The late Holocene mud wedge on the Adriatic shelf offshore Ortona, Italy, shows undulating sub-pa... more The late Holocene mud wedge on the Adriatic shelf offshore Ortona, Italy, shows undulating sub-parallel seismic reflector sequences which extend several kilometres along strike and 100-200 m down-dip in water depth between 20 and 80 m. The amplitude of such undulations is up to 5 m and the undulations continue as stacked sediment packages downwards throughout the 35 m thick mud wedge. The undulations are separated by 4°to 5°dipping boundary zones and at first glance these sediment undulations resemble the seafloor sedimentary structures visible in the Humboldt Feature offshore California. There is an ongoing debate whether seafloor undulations are the result of deformation processes or sediment deposition and/or reworking due to submarine shelf currents. A dense net of recently reprocessed and digitally interpreted high-resolution Chirp seismic data on the Adriatic shelf favours an interpretation that these undulations developed, in the upper part of the stratigraphic section through sediment reworking rather than through deformation. There are three lines of evidence for this: (1) the spatial extent of the undulations coincides with higher seabed reflector amplitudes than found both on the shelf and in the distal part of the shelf. If the features were solely caused by slope failure there should be no change of amplitudes, (2) the seabed reflector amplitude is generally higher on the gently dipping or flat upslope limbs than on the steeper downslope limbs, supporting a current origin that causes preferred deposition of sediments with higher acoustic impedance on the top, (3) the boundaries between the undulations are dipping at angles that are much lower than the angle of internal friction of these sediments excluding that a simple model like the Mohr-Coulomb under gravitational loading could describe the undulations as sediment deformation and failures.

Research paper thumbnail of A geomechanical approach for the genesis of sediment undulations on the Adriatic shelf

Geochemistry Geophysics Geosystems, 2008

This study is among the first to examine the genesis of the seafloor and subsurface undulations o... more This study is among the first to examine the genesis of the seafloor and subsurface undulations on the Adriatic continental shelf by integrating stratigraphic information and in situ and laboratory geotechnical measurements. Interpretation of sediment behavior is based on a 32-m-long borehole crossing (1) a possible shear plane and (2) a silty clay layer at about 20 m below seafloor (mbsf) on which sediment undulations are rooted and could be interpreted as a potential weak layer succession. Our main results in terms of triggering mechanism for the observed undulations show that under an earthquake, liquefaction and/or failure of the silty-clay sediments (weak layer) leading to deformation of the upper more cohesive sediments is possible only when such a layer is buried by less than 5 m. For greater burial thicknesses, this silty clay becomes stable under the confining lithostatic pressure exerted by the overlying sediment. This work shows that the seafloor and subsurface undulations observed in the study area are most probably the result of an early deformation process of the seafloor followed by a depositional process.

Research paper thumbnail of 26th December 2004 great Sumatra–Andaman earthquake: Coseismic and post-seismic motions in northern Sumatra

Earth and Planetary Science Letters, 2007

Trench-parallel thrust faults verging both landward and seaward were mapped in the portion of wed... more Trench-parallel thrust faults verging both landward and seaward were mapped in the portion of wedge located between northern Sumatra and the Indian-Indonesian boundary. The spatial aftershocks distribution of the 26th December 2004 earthquake shows that the post-seismic motion is partitioned along two thrust faults, the Lower and Median Thrust Faults, the latter being right-laterally offset by a N-S lower plate fracture zone located along the 93.6°N meridian. Between February 2005 and August 2005, the upper plate aftershock activity shifted from southeast of this fracture zone to northwest of it, suggesting that the lower plate left-lateral motion along the fracture zone may have induced a shift of the upper plate post-seismic activity along the Median Thrust Fault. Based on swath bathymetric and 3.5 kHz data, co-seismic deformations were weak close to the trench. Joint seismic-geodetic determination of slip distribution and time arrivals and heights of tsunami waves suggest that the coseismic slip was maximum along a portion of the Upper Thrust Fault located north of the Tuba Ridge, suggesting that the Upper Thrust Fault might be a splay fault originated at the interplate fault plane. As the Upper Thrust Fault is steeper than the slab, the vertical motion of the adjacent Outer Arc and overlying water is much larger compared to the one resulting from slip on the megathrust alone, increasing tsunamogenic effects.

Research paper thumbnail of A review of undulated sediment features on Mediterranean prodeltas: distinguishing sediment transport structures from sediment deformation

Marine Geophysical Researches, 2010

Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene w... more Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and hydrodynamic time series and hydrographic transects. In this study we show that the characteristics of the sediment undulations (configuration of the reflections down section and between adjacent undulations and overall morphologic characteristics) are incompatible with a genesis by sediment deformation alone and do not show evidence of sediment deformation in most cases. Various processes in the benthic boundary layer can be invoked to explain the variety of features observed in the numerous areas displaying sediment undulations.

Research paper thumbnail of Coastal dynamics under conditions of rapid sea-level rise: Late Pleistocene to Early Holocene evolution of barrier–lagoon systems on the northern Adriatic shelf (Italy

Quaternary Science Reviews, 2008

This multidisciplinary case study of two preserved barrier systems combined the analysis of radio... more This multidisciplinary case study of two preserved barrier systems combined the analysis of radiocarbon datings, grain-size distributions, high-resolution seismics, and shelf bathymetry with reconstructions of palaeo-environmental conditions (tides, waves, sea-level change) and forward modelling of barrier-lagoon systems, to provide an integrated view of the coastal transgressive evolution of a large sector of the northern Adriatic shelf between 15 and 8 ka BP. Palaeoenvironmental reconstructions point to increased tidal amplitude, low-energy wave climate and high rates of sea-level rise (up to 60 mm/a) during the formation of the oldest preserved barrier system (not, vert, similar90 m water depth; 14.3 cal ka BP). A younger barrier system (42 m water depth; 10.5 cal ka BP) formed under conditions of lower tidal amplitude, higher wave energy and a lower rate of sealevel rise (10 mm/a).