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See detailInfluence of bottom currents on the sedimentary processes at the western tip of the Gulf of Corinth, Greece
Beckers, Arnaud ULg; Beck, Christian; Hubert, Aurelia ULg et al

in Marine Geology (2015)

We investigated the sedimentary processes that were active during the Holocene in the Gulf of Corinth, using high-resolution seismic reflection profiles and gravity cores. Seismic reflection data clearly ... [more ▼]

We investigated the sedimentary processes that were active during the Holocene in the Gulf of Corinth, using high-resolution seismic reflection profiles and gravity cores. Seismic reflection data clearly show the presence of shallow-water sediment drifts at the western end of the Gulf, close to the Rion Sill that links the gulf to the Ionian Sea. Short cores indicate that drifts are composed of homogenous bioturbated mud in their upper part. The drift deposits flank a wide central area where the sea floor is eroded and where pre-Holocene deposits locally outcrop. The sea floor morphology in this area is marked by furrows oriented in different directions and by a depression attributed to the action of bottom-currents. The magnetic fabric of sediment samples from the drift, shelves, sub-basins and from the basin floor show a significant anisotropy and a similar orientation of Kmax axes along core. The largest anisotropy (P = 1.043 ± 0.007) is observed in the drift and is interpreted as resulting from the action of bottom currents. The similar orientation of Kmax axes in the other cores, collected from areas East of the drifts, suggests that bottom currents also affect sediment deposition in the rest of the study area, even if seismic profiles and core analyses demonstrate that gravitational processes such as submarine landslides and turbidity currents exert the main control on sediment transport and deposition. Average Kmax axes for four cores were reoriented using the declination of the characteristic remanent magnetization. Kmax axes show variable orientations relatively to the slope of the sea floor, between along-slope and roughly parallel to the contour lines. [less ▲]

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See detailSedimentary impacts of recent moderate earthquakes in different settings in the Western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Mortier, Clément; Beck, Christian et al

Poster (2015, April 21)

11 short gravity cores retrieved in the Western Gulf of Corinth, Greece, allowed identifying event deposits whose age ranges were compared to an updated earthquakes catalogue for the area. 210Pb-derived ... [more ▼]

11 short gravity cores retrieved in the Western Gulf of Corinth, Greece, allowed identifying event deposits whose age ranges were compared to an updated earthquakes catalogue for the area. 210Pb-derived age-depth curves show that the majority of the event deposits may have been triggered by earthquakes. These results show that moderate earthquakes (Mw ~6.0-6.5) may significantly impact different marine settings, from shallow shelves (70-100 m deep) to the basin floor (330 m deep). The deepest coring sites show the best possible record, but one major earthquake is missing and the age of one event deposit does not fit with any known earthquake. More cores are needed to check the spatial extent of each deposit and to validate the absence of record of some earthquakes, like the 1995 Aigion earthquake. [less ▲]

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See detailBasement depth and sedimentary infill from deep seismic reflection data at the western tip of the offshore Corinth Rift
Beckers, Arnaud ULg; Tripsanas, Efthymios; Hubert, Aurelia ULg et al

Conference (2015, April 17)

The Corinth rift is a young continental rift located in central Greece. The active part of the rift forms an E-W striking depression – the Gulf of Corinth – that is the deepest in its central part ... [more ▼]

The Corinth rift is a young continental rift located in central Greece. The active part of the rift forms an E-W striking depression – the Gulf of Corinth – that is the deepest in its central part. Extensive seismic surveys have imaged the basin's basement and allowed to estimate the total extension across most of the Gulf except its western tip. Extension is high in the central part and decreases westward and eastward, as reflected in the present-day bathymetry. Two decades of GPS measurements have shown that the extension rate increases westwards from ~5 to 10-15 mm yr-1, but this is not consistent with the long term pattern. However, no data allowed so far to estimate the basement depth at the western tip of the Gulf, where the geodetic extension rate is the largest. Such data would allow to check the apparent inconsistency between the present rate and the long-term estimates of crustal extension. We present here an unpublished multichannel seismic line dating from 1979 and crossing the western tip of the Gulf of Corinth. The line is 22 km long and strikes WNW-ESE, from the Mornos delta to the West-Channel fault. A Maxipulse source has been used, allowing to image the basement below the synrift sedimentary infill. To the east, a ~1.6 km deep basin is imaged between the southern margin of the Gulf and an inactive south-dipping fault located between the Aigion and the Trizonia faults. The sedimentary infill consists in an alternation between basin-focused bodies made of incoherent reflections and more extensive high-amplitude reflectors. Attributing this alternation to eustatic variations give an age of 300-350 ka to the oldest well imaged deposits. Northwest of the Trizonia fault, the basement is imaged at shallower depth, i.e. ~450 m. The western tip of the seismic line reaches the Mornos delta, close to the northern shoreline. There, the depth to the basement is larger, reaching ~1.2 km. The infill is made of 3 units : on the basement lies a thin unit of incoherent reflections that may corresponds to coarse-grained fluvial deposits. A second unit of parallel, high-amplitude, low-frequency reflections could represent deeper-water deposits. The last seismic unit represents the Mornos delta coarse-grained deposits, from 0 to ~0.7 km deep. The depth of the basement deduced from this seismic line at the western tip of the Gulf of Corinth (1.2-1.6 km) is shallower than the one in the central part of the Gulf (2.5-3 km). This reinforce the inconsistency between long-term and short-term rates of extension in the Corinth Rift, which may be explained by assuming that the Western Corinth Rift initiated much later than the Central Rift. These data also allow to constrain the total displacement on the N-dipping Psathopyrgos fault, one of the major, normal, basin-bounding faults at the western tip of the Rift. The total offset would reach 2.1-2.3 km and the uplift/subsidence ratio would be ~1:1.7, implying a slip rate of 2.2-2.5 mm yr-1 based on footwall uplift rate data. [less ▲]

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See detailPatterns of Quaternary uplift of the Corinth rift southern border (N Peloponnese, Greece) revealed by fluvial landscape morphometry
Demoulin, Alain ULg; Beckers, Arnaud ULg; Hubert, Aurelia ULg

in Geomorphology (2015), 246

The Rift of Corinth is a world-class example of young active rifting and, as such, is an ideal natural laboratory of continental extension. However, though much investigated for two decades, several ... [more ▼]

The Rift of Corinth is a world-class example of young active rifting and, as such, is an ideal natural laboratory of continental extension. However, though much investigated for two decades, several aspects of the mechanisms at work are still poorly understood. The aim of this paper is a detailed morphometric study of the fluvial landscape response to the tectonic uplift of the rift southern shoulder in order to reconstruct the rift's Quaternary evolution, with special attention to timing, location, and intensity of uplift episodes. Based on the use of a large set of catchment and long profile metrics complemented by the newR/SR integrative approach of the regional drainage network, we identified three distinct episodes of uplift of the northern Peloponnese coastal tract, of which the intermediate one, dated around 0.35–0.4 Ma, is only recorded in the topography of the central part of the rift shoulder, and the youngest one appears to have propagated from east to west over the last 10–20 ka. While net uplift remained minimum in the eastern part of the study area during the whole Quaternary, it shows a clear maximumin the central part of the rift shoulder since 0.4 Ma and an eastward shift of this maximumin recent times. Maximum uplift rates calculated from the morphometric data are of N1.05 and 2–5 mmyear−1 for, the mid-Middle Pleistocene and Holocene uplift episodes, respectively. The morphometric evidence reveals an onshore uplift history remarkably consistent with the rift evolution reconstructed from other data sets. In the long term, it shows a stable pattern of maximum activity in the central part of the rift, confirming previous conclusions about the absence of rift propagation. In the short term, it sheds light on a possible E–Wmigration of the zone of recent uplift, suggesting that in the near future fault activity and seismic hazard might concentrate in the Heliki–Aegion area, at the western tip of this uplift wave. [less ▲]

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See detailActive faulting at the western tip of the Gulf of Corinth, Greece, from high-resolution seismic data
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

in Marine Geology (2015)

The Gulf of Corinth is one of the fastest-spreading intra-continental rifts on Earth. GPS data indicate that the rift is currently opening in a NNE-SSW direction, with a rate of extension reaching up to ... [more ▼]

The Gulf of Corinth is one of the fastest-spreading intra-continental rifts on Earth. GPS data indicate that the rift is currently opening in a NNE-SSW direction, with a rate of extension reaching up to 16 mm yr-1 in its westernmost part. Although the rest of the offshore rift has been well studied, the western tip of the rift is still poorly explored. We present an accurate map of submarine faults in this area based on two high-resolution seismic reflection surveys (single channel sparker). In the eastern part of the studied area, the sedimentary infill is affected by the known North Eratini, South Eratini and West Channel faults. Further to the west, the seafloor is mostly flat, and is bounded to the north by the normal, south-dipping, Trizonia fault. To the north, the shallower part of the Gulf shows to the east a diffuse pattern of normal and strike-slip deformation which is replaced to the west by a 7.5 km long SE striking strike-slip fault zone, called the Managouli fault zone. To the westernmost tip of the Gulf, in the Nafpaktos Basin, two fault sets with different strikes are encountered; the one with aNE-SW strike exhibits a clear strike-slip component. The western tip of the Gulf of Corinth is the only part of the Corinth Rift where convincing evidence for strike-slip movement has been found. This fault pattern is likely related to the complex deformation occurring at the diffuse junction at the western tip of the Rift between three crustal blocks: Continental Greece, Peloponnese, and the Ionian Island-Akarnia block. [less ▲]

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See detailEvidence for Holocene bottom-currents erosion in the Western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Beck, Christian; Hubert, Aurelia ULg

Poster (2014, September 10)

The Gulf of Corinth, Greece, is connected to the Ionian Sea through a 62 m deep sill. Strong tidal currents have been measured above this sill, what could potentially induce bottom-current erosion in the ... [more ▼]

The Gulf of Corinth, Greece, is connected to the Ionian Sea through a 62 m deep sill. Strong tidal currents have been measured above this sill, what could potentially induce bottom-current erosion in the Gulf. Seismic reflexion data allowed us to identify this present-day expected seafloor erosion in a wide area, as well as erosional unconformities and a wide channel between 100 and 300 m below sea level. These features highlight the possible occurrence of strong bottom-currents since the last sea level rise. [less ▲]

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See detailEarthquake imprints on 400 years of marine sedimentation in the western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

Poster (2014, August 18)

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is ... [more ▼]

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is the highest of the whole Corinth Rift. The question of seismic hazard is consequently particularly relevant. In this framework, we investigated the offshore sediments in order to look for sedimentary signature of past earthquakes. 12 short gravity cores have been retrieved in different environments: two shelves (40 and 100 m deep), one sub-basin (180 m deep) and the deep Gulf axis (330 m deep). The cores are 0.5 to 0.85 m long, permitting to analyze up to 400 yrs of sedimentation. Several sedimentological analyses have been performed: magnetic susceptibility, grain-size, XRF, ASM. Chronology is based on 137Cs and 210Pb decay. In parallel, an in-depth analysis of existing and newly found documents has been done to re-interpret macroseismic intensity fields of historical earthquakes and to build an updated earthquake catalogue for the area. These new data allowed us to estimate a macroseismic intensity threshold for submarine slope failures in the area, based on 16 reported events. Sedimentary events have been identified in all cores. On the first shelf, despite a visually homogenous, silty, sedimentation, 3 events have been highlighted by high resolution grain-size analysis and 210Pb decay profile’s disturbances. The upper one could be a back-wash flow tsunami deposit. On the second shelf, 4 high-concentration density flow deposits occurred with a recurrence time of ~58 yrs. In the canyon and in the sub-basin, sandy turbidites occurred with recurrence times of ~26 and ~56 years respectively. The possible seismic origin of these deposits is discussed based on their sedimentary characteristics and the macroseismic intensities assessed for the sediments source areas for each core location. [less ▲]

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See detailPhénologie et intensité de la migration postnuptiale diurne en Ardenne du nord-est par le suivi migratoire (Ramecroix, 2006 à 2010)
Beckers, Arnaud ULg; Baron, André

in Aves (2014), 51(2), 87-106

We present the results of five years of monitoring postnuptial migration in the northeast Ardennes (the Ramecroix site) from 2006 to 2010. The timing and intensity of migration have been calculated for ... [more ▼]

We present the results of five years of monitoring postnuptial migration in the northeast Ardennes (the Ramecroix site) from 2006 to 2010. The timing and intensity of migration have been calculated for the 19 commonest species. Phenology for each species varied markedly from year to year. The passage of two particular species (Northern Lapwing and Song Trush) was extremely concentrated in time. Comparison with data from the Netherland and from Les Awirs (Liège, Belgium) show differences between locations, for which we propose some explanations. The full dataset constitute a useful benchmark for future studies on the spatial variability of migration flow. [less ▲]

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See detailThe paleoearthquake record of the Cinarcık Segment of the North Anatolian Fault in the Marmara Sea (Turkey) and its implication regarding past historical rupture scenario across the Marmara Sea
Hubert, Aurelia ULg; Drab, Laureen; Albini, P et al

Scientific conference (2014, July 07)

Istanbul and its 12 million inhabitants borders the Marmara Sea, a submarine pull-apart basin related to the North Anatolian Fault (NAF), a major strike slip fault that ruptures in M>7 earthquakes ... [more ▼]

Istanbul and its 12 million inhabitants borders the Marmara Sea, a submarine pull-apart basin related to the North Anatolian Fault (NAF), a major strike slip fault that ruptures in M>7 earthquakes. Constraining the recurrence rate of M>7 earthquakes that threaten the megacity is problematic because the active faults are submarine. For assessing past submarine earthquake ruptures of the Cinarcik Fault Segment located just south of Istanbul, we studied two sedimentary cores and identified seismoturbidites related to historical ruptures. Earthquake related turbidites are identified in both cores, based on their distinctive sedimentological and geochemical signatures. The seismoturbidites recorded in one of the core named Klg04 are inferred to record only mass wasting events related to the rupture on the Cinarcik Segment because of its specific geomorphological location. To constrain the seismoturbidites chronology, we combine short-lived radionuclide, radiocarbon and paleoinclination data. The first four seismoturbidites recorded match the 1894, 1509, 14th century and 989 historical earthquakes. The obtained age model allows us to discuss past historical rupture scenario across the Marmara Sea. The fact that the 1766 earthquakes are not recorded is further discussed based on new macroseismic intensity data and sedimentary records East of the Cinarcik Basin. [less ▲]

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See detailSpatiotemporal distribution of last 500 yrs turbidites in the Western Gulf of Corinth, Greece: implications for the characterization of historical earthquakes
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

Poster (2014, July 01)

The Corinth rift is one of the fastest spreading rifts on Earth. 10 earthquakes of magnitude greater than 6 occurred during the last century. The question of seismic hazard is consequently particularly ... [more ▼]

The Corinth rift is one of the fastest spreading rifts on Earth. 10 earthquakes of magnitude greater than 6 occurred during the last century. The question of seismic hazard is consequently particularly relevant. Despite a long earthquake catalogue, estimations of earthquake hazard remain problematic because of the difficulty to associate each historical event to one of the many active faults mapped in the area. Consequently, combining seismology, history and paleoseismology in an interdisciplinary approach is here necessary and is the goal of the ANR-SISCOR project. In this framework, we investigated the offshore sediments in order to (1) better constraint the length of the active offshore faults, and (2) look for sedimentary signature of historical earthquakes. 600 km of high resolution seismic reflexion data have been acquired during two surveys and 12 short gravity cores have been retrieved. The latters are 0.5 to 1 m long, allowing us to analyze about 500 yrs of sedimentation. Two new faults potentially able to trigger M>5.5 earthquakes have been mapped in the northern part of the gulf based on seismic data. Sedimentary events (turbidites sensu lato) have been identified in some cores, essentially in the deep basin and in a 180m-deep sub-basin close to the northern coast. The comparison with the critically reviewed historical records shows that some of these events could have been triggered by historical earthquakes. The link between these potential earthquakes sedimentary signatures, historical events and active faults is discussed based on intensity maps and our new active fault map. [less ▲]

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See detailThe Amik Lake in Southern Turkey over the last 4000 years, a new paleoseismological record of ruptures along the Northern Dead Sea Fault
Hubert, Aurelia ULg; El Ouahabi, Meriam ULg; Lebeau, Hèlène et al

Poster (2014, June 30)

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle ... [more ▼]

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle East extending from the Red Sea in the south to the East Anatolian Fault Zone in the north. Around the Amik Basin, continuous human occupation is attested since 6000-7000 BC. Indeed the low-lying Amuq plain is covered by tell settlements first explored by Robert Braidwood in the 1930s. Our objective in this presentation is to look at major paleo-environmental changes recorded in the Amik Lake over the last 4000 years and in particular its potential paleoseimic sedimentary record. The lake has been drained and progressively dried up since the mid-50s so that it is not watered during the summer season and constitutes a unique opportunity to collect sediment records. Sediments were collected at 1 cm to 2 cm intervals in a trench and in cores up to a depth of 5 meters in the clay deposits. A diverse array of complementary methods is applied to study the records: magnetic susceptibility, grain size, organic matter and inorganic carbon (L.O.I), XRD mineralogy, XRF geochemistry, carbon geochemistry and clay mineralogy. The age of the record is constrained combining radionuclide and radiocarbon dating. The sedimentary record shows large earthquake related structural disturbances and smaller siliciclastic sedimentary events. The siliciclastic input would be related to enhanced detritical sedimentation related to earthquake shaking. The latter is further investigated looking at intensities and shake maps related to the last 19th century M>7 earthquakes in the area and landslide prone area in the lake catchment. [less ▲]

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See detailPaléosismologie marine et failles actives dans le golfe de Corinthe (Grèce)
Beckers, Arnaud ULg; Beck, Christian; Hubert, Aurelia ULg et al

Scientific conference (2014, May 19)

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See detailContribution of a new active faults map and sedimentary cores to the characterization of seismogenic sources in an interdisciplinary approach (Western Gulf of Corinth, Greece)
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

Conference (2014, April 28)

The Corinth rift is one of the fastest spreading rifts on Earth. 5 earthquakes of magnitude greater than 5.8 occurred during the last 40 years. The question of seismic hazard is consequently particularly ... [more ▼]

The Corinth rift is one of the fastest spreading rifts on Earth. 5 earthquakes of magnitude greater than 5.8 occurred during the last 40 years. The question of seismic hazard is consequently particularly relevant. Despite a long earthquake catalogue, estimations of earthquake hazard remain problematic because of the difficulty to associate each historical event to one of the many active faults mapped in the area. Consequently, combining seismology, history and paleoseismology in an interdisciplinary approach is here necessary and is the goal of the ANR-SISCOR project. In this framework, we investigated the offshore sediments in order to (1) better constraint the length of the active offshore faults, and (2) look for sedimentary signature of historical earthquakes. 600 km of high resolution seismic reflexion data have been acquired during two surveys and 12 short gravity cores have been retrieved. The latters are 0.5 to 1 m long, allowing us to analyze about 500 yrs of sedimentation. Two new faults potentially able to trigger M>5.5 earthquakes have been mapped in the northern part of the gulf based on seismic data. Sedimentary events (turbidites and mud flows) have been identified in some cores, essentially in the deep basin and in a 180m-deep sub-basin close to the northern coast. The comparison with the critically reviewed historical records shows that some of these events could have been triggered by historical earthquakes. The link between these potential earthquakes sedimentary signatures, historical events and active faults is discussed based on intensity maps and our new active fault map. [less ▲]

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See detailMarine paleoseismology in the Western Gulf of Corinth (Greece) for the last 500 years
Beckers, Arnaud ULg; Mortier, Clément; Beck, Christian et al

Scientific conference (2014, January 15)

Related to the Gulf of Corinth rifting, five earthquakes of magnitude greater than 5.8 occurred in the last 35 years. Consequently, the question of earthquake (EQ) hazard is particularly relevant. Onland ... [more ▼]

Related to the Gulf of Corinth rifting, five earthquakes of magnitude greater than 5.8 occurred in the last 35 years. Consequently, the question of earthquake (EQ) hazard is particularly relevant. Onland, paleoseismological data are scarce and offshore data were absent before the present study. We investigated recent sediments bounding three well-defined major seismogenic faults. We retrieved 12 gravity cores from 50 to 85 cm long in three distinct sites: the southern shelf (40 to 50 m deep), a 180 m deep sub-basin, and a transect from the southern coast to the center of the gulf. We performed grain size analysis, magnetic susceptibility, loss on ignition and geochemical (X-Ray Fluorescence) measurements on cores from each site. We sought to identify layers potentially attributed to EQ-related processes like liquefaction and tsunamis for the sites on the shelves or mass transport and turbidity currents for the basins. Chronology is based on 137Cs (Atmospheric Nuclear Experiments) and 210Pb decay. Considering sedimentation rates estimates in these areas, the longer cores record about 500 years of sedimentary archives. On the southern shelf, 3 coarser layers have been identified at identical depth in 3 cores. 210Pb decay show erosion just under the first event that we attributed to the 1995 tsunami (backwash flow deposit). In the 180m deep sub-basin, among 3 clear grain-size peaks, two have been attributed to the 1817 Aegion EQ and the 1660 Galaxidi EQ. In last site, 10 “events” (grain-size and Zr/Rb peaks) have been identified in the deepest part of the transect 4 on the shelf. Their analysis is in progress, as well as paleomagnetic measurements. [less ▲]

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See detailLate Quaternay sedimentation and active faulting in the Western tip of the Gulf of Corinth, Greece
Hubert, Aurelia ULg; Beckers, Arnaud ULg; Beck, Christian et al

Poster (2013, November 06)

The Gulf of Corinth is one of the fastest-spreading intracontinental rifts on Earth. Present day kinematics (GPS data) indicates an opening direction oriented NNE-SSW and an opening rate increasing ... [more ▼]

The Gulf of Corinth is one of the fastest-spreading intracontinental rifts on Earth. Present day kinematics (GPS data) indicates an opening direction oriented NNE-SSW and an opening rate increasing westward from 11 mm y-1 in the central part to 16 mm y-1 in the westernmost part. A significant part of the deformation is localized offshore, where the fault geometry was not well known yet. The high extension rate would imply a high seismic hazard if faults are not creeping. We propose an accurate map of submarine faults in the western extremity of the Gulf of Corinth. The map is based on two high-resolution seismic reflection surveys (single channel sparker) performed aboard HCMR’s R/V ALKYON, within the frame of SISCOR ANR Project. About 600 km of seismic lines were acquired, with a 200 msTWTT maximum penetration down to what we infer to represent the MIS 5 discontinuity. Depocenters location is controlled by river deltas where up to 75m of post-LGM sediments are stored. Numerous, up to 15m thick, mass transport deposits fill the central and eastern parts. In the eastern part, the sedimentary infill is faulted by the known North Eratini, South Eratini and West Channel faults. At the longitude of the Trizonia Island, the seafloor in mainly horizontal and the only fault is the south dipping Trizonia fault. Between the Trizonia Island and the Mornos Delta, the shallower northern part of the gulf shows a diffuse pattern of deformation with faults striking mainly E-W and ESE-WNW. It shows south and north dipping normal faults, strike-slip faults, as well as an inherited basement relief. To the West, three young grabens have been identified, striking NE-SW and W-E. The northern, 6 km long, fault in this grabens system shows a clear strike-slip component (fig.1). [less ▲]

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See detailPotential paleoseismological records in the Western Gulf of Corinth sediments (Greece) for the last 500 years
Beckers, Arnaud ULg; Mortier, Clément; Beck, Christian et al

Conference (2013, November 06)

Related to the Gulf of Corinth rifting, five earthquakes of magnitude greater than 5.8 occurred in the last 35 years. Consequently, the question of earthquake (EQ) hazard is particularly relevant. Onland ... [more ▼]

Related to the Gulf of Corinth rifting, five earthquakes of magnitude greater than 5.8 occurred in the last 35 years. Consequently, the question of earthquake (EQ) hazard is particularly relevant. Onland paleoseismological data are scarce and offshore data were absent before the present study. We investigated recent sediments bounding three well-defined major seismogenic faults: Aegion, Trizonia and Psathopyrgos faults. We retrieved 12 gravity cores from 50 to 85 cm long in three distinct sites: the southern shelf (40 to 50 m deep), a 180 m deep sub-basin, and a transect from the southern coast to the center of the gulf. Chronology is based on 137Cs (Atmospheric Nuclear Experiments) and 210Pb decay for two sites (Aegion and Trizonia). Considering sedimentation rates estimates in these areas, the longer cores record about 500 years of sedimentary archives. We performed granulometry, magnetic susceptibility, loss on ignition and geochemical (X-Ray Fluorescence) measurements on cores from each site. Some samples were observed with a binocular to identify the nature of the grains. We sought to identify layers potentially attributed to EQ-related processes like liquefaction and tsunamis for the sites on the shelves or mass transport and turbidity currents for the basins. In Aegion, 3 coarser layers have been identified at identical depth in 3 cores across the scarp. 210Pb decay show erosion just under the first event, that we attributed to the 1995 tsunami (backwash deposit) (figure). In the Trizonia Sub-Basin, among 3 clear grain-size peaks, two have been attributed to the 1817 Aegion EQ and the 1660 Galaxidi EQ. In Psathopyrgos, 10 “events” (grain-size and Zr/Rb peaks) have been identified in the deepest part of the transect and at least 2 on the shelf. Their analysis is in progress. [less ▲]

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See detailContribution of land use changes to future flood damage along the river Meuse in the Walloon region
Beckers, Arnaud ULg; Dewals, Benjamin ULg; Erpicum, Sébastien ULg et al

in Natural Hazards & Earth System Sciences (2013), 13

Managing flood risk in Europe is a critical issue because climate change is expected to increase flood hazard in many european countries. Beside climate change, land use evolution is also a key factor ... [more ▼]

Managing flood risk in Europe is a critical issue because climate change is expected to increase flood hazard in many european countries. Beside climate change, land use evolution is also a key factor influencing future flood risk. The core contribution of this paper is a new methodology to model residential land use evolution. Based on two climate scenarios (“dry” and “wet”), the method is applied to study the evolution of flood damage by 2100 along the river Meuse. Nine urbanization scenarios were developed: three of them assume a “current trend” land use evolution, leading to a significant urban sprawl, while six others assume a dense urban development, characterized by a higher density and a higher diversity of urban functions in the urbanized areas. Using damage curves, the damage estimation was performed by combining inundation maps for the present and future 100 yr flood with present and future land use maps and specific prices. According to the dry scenario, the flood discharge is expected not to increase. In this case, land use changes increase flood damages by 1–40 %, to EUR 334–462 million in 2100. In the wet scenario, the relative increase in flood damage is 540–630 %, corresponding to total damages of EUR 2.1–2.4 billion. In this extreme scenario, the influence of climate on the overall damage is 3–8 times higher than the effect of land use change. However, for seven municipalities along the river Meuse, these two factors have a comparable influence. Consequently, in the “wet” scenario and at the level of the whole Meuse valley in the Walloon region, careful spatial planning would reduce the increase in flood damage by no more than 11–23 %; but, at the level of several municipalities, more sustainable spatial planning would reduce future flood damage to a much greater degree. [less ▲]

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