References of "Hubert, Aurelia"
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Peer Reviewed
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 ▲]

Detailed reference viewed: 10 (3 ULg)
Peer Reviewed
See detailUnderstanding of the diversity of earthquake turbiditic flows in a single lake: the case of the Lake Hazar on the East Anatolian Fault
Lamair, Laura ULg; Hage, Sophie ULg; Hubert, Aurelia ULg et al

Poster (2014, August)

The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia ... [more ▼]

The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia collision zone. The East Anatolian Fault ruptured over most of its length during the 19th century in a series of magnitude ~7 earthquakes. During the 20th century this fault was less active with only two events of magnitude greater than 6. This absence of large earthquakes has resulted in relatively little attention being paid to the East Anatolian Fault compared to the North Anatolian Fault, which has ruptured during the last century in several earthquakes of Ms~7. To constrain the seismic history of the East Anatolian Fault in its central part, we focus on the Hazar Lake, occupying a 20 km long pull-apart basin. Short cores and long sedimentary cores were collected at three different sites to retrieve a paleoseismic record. Small correlative coarse-grained sedimentary events are identified in all cores. The age of the events is inferred combining radiocarbon and radionuclide (137 Cs and 210Pb) dating. We present here detailed analyses of three sedimentary events assigned respectively to the historical earthquakes occurring in 1789, 1513-1514, 1285. The source of the sedimentary events is different at the three sites. We combine X-ray imagery, magnetic susceptibility, grain-size and XRF measurements with thin section analysis to investigate the nature of sedimentary events. The analyses show first that the three sedimentary events are different. The magnitude of the terrigenous signal varies significantly. Second the correlative events have a different expression at the three sites. So each site has a different and specific sensitivity. In particular, an individual event can be composed of several coarse-grained sub-events of different magnitude with a time lapse in between greater than a week. The latter is reveals by the presence of bioturbation in particular by chironomids in individual thin sand layers. Thin section also shows that subevents are gradded. Each coarse-grained layer is thus a separated turbiditic flow. The site with the highest sensitivity is the one located near the near-shore steep submarine southern slopes overhanged by the steep subaerial slopes of the Hazar Mountains. The rivers draining the Hazar Mountains are ephemeral and provide a restricted sedimentary supply. In addition, seismic reflection data show that the submarine slopes do not to accumulate a significant sedimentary load. However on these steep slopes, an earthquake intensity of 6 or less is enough to trigger a slope failure and the associated turbiditic flow. We conclude that the different sub-events at this site may record a complete earthquake sequence, i.e the main-shock and its foreshocks and aftershocks. [less ▲]

Detailed reference viewed: 27 (1 ULg)
Peer Reviewed
See detailHARBIYE AQUEDUCT: A RECORD OF PAST EARTHQUAKES
Lamair, Laura ULg; Degée, Hervé ULg; Hubert, Aurelia ULg et al

Poster (2014, August)

This paper presents a detailed analysis of Harbiye aqueduct (Hatay, Turkey). The region is situated at the junction of two major faults (East Anatolian fault and the Dead Sea fault) and is well known for ... [more ▼]

This paper presents a detailed analysis of Harbiye aqueduct (Hatay, Turkey). The region is situated at the junction of two major faults (East Anatolian fault and the Dead Sea fault) and is well known for his important historic seismicity. The aqueduct is located close to Antioch on the Orontes (known as Antakya). The city was founded in the third century BC. Harbiye aqueduct is characterized by different stages of building (Benjelloun et al., submitted). A phase is dated to Caligula period. After the 37 AD earthquake, the aqueduct was rebuilt. We noticed the presence of two dissociated travertine and a changing of masonry material. We also observed several damages and repair structures dating from Roman time. We assume that our observations are the results of one or more earthquakes. Since the construction of the aqueduct, historical seismic records mention 13 earthquakes that provoked severe damages in the city of Antioch (Guidoboni et al. 1994, Al-Tarazi, 1999, Över et al. 2002). The last one occurred in 1872 (M=7.2). In order to test our hypothesis, we modelled the structure of the aqueduct by using FineLg, a software developed at University of Liege. The seismic signals were chosen in the European Strong-motion database (Ambraseys et al., 2002) according the following criteria: a bedrock station (to avoid site effect), a strike-slip fault mechanism and a distance between the station and the epicenter around 20-30 km. The aqueduct is located at about 25 km of the Dead Sea Fault. We tested several magnitudes for the purpose of estimate the magnitude of the earthquake(s) which destroy(s) the studied aqueduct. Our results highlight the bond between the magnitude, the damage and the weakness area of this type of structure. [less ▲]

Detailed reference viewed: 34 (3 ULg)
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

Poster (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 ▲]

Detailed reference viewed: 19 (3 ULg)
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 ▲]

Detailed reference viewed: 17 (1 ULg)
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 ▲]

Detailed reference viewed: 37 (5 ULg)
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)

Detailed reference viewed: 18 (2 ULg)
Peer Reviewed
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 ▲]

Detailed reference viewed: 39 (3 ULg)
See detailPaleoenvironmental record of the Amik Basin (Amuq Plain, Southern Turkey) over the last 4000 years
Hubert, Aurelia ULg; El Ouahabi, Meriam ULg; Lebeau, Hélène ULg et al

Poster (2014, February 04)

Continous human occupation is attested in the Amik Basin since 6000-7000 BC. The low-lying Amuq plain is covered by tell settlements first explored by Robert Braidwood in the 1930s. The Basin also is ... [more ▼]

Continous human occupation is attested in the Amik Basin since 6000-7000 BC. The low-lying Amuq plain is covered by tell settlements first explored by Robert Braidwood in the 1930s. The Basin also 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 Turkey in the north. The study focuses on the sedimentary record of the Amik Lake occupying the central part of the Basin. Our objective is to constrain major paleo-environmental changes in the area over the last 4000 years and assess possible human impact. 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. The age of the record is constrained combining radionuclide and radiocarbon dating. The record shows two intense phases of soil erosion with enrichments in Chromium and Nickel. The most recent erosion phase might be linked with enhanced development during the Roman and the growth of the Antioch City. The oldest one would occur around 3000 BC. The record also allows reconstructing past lake level variations and discusses the results in comparison with variations of the Dead Sea. [less ▲]

Detailed reference viewed: 31 (1 ULg)
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 ▲]

Detailed reference viewed: 34 (2 ULg)
Peer Reviewed
See detailA 3400 year lacustrine paleoseismic record from the North Anatolian Fault, Turkey: Implications for bimodal recurrence behavior
Avsar, Ulas; Hubert, Aurelia ULg; De Batist, Marc et al

in Geophysical Research Letters (2014), 41(2), 377-384

High-resolution physical, geochemical, and geochronological analyses on the sedimentary sequence of Yeniçağa Lake, located in a fault-bounded basin along the North Anatolian Fault, reveal fingerprints of ... [more ▼]

High-resolution physical, geochemical, and geochronological analyses on the sedimentary sequence of Yeniçağa Lake, located in a fault-bounded basin along the North Anatolian Fault, reveal fingerprints of paleoearthquakes. A robust sediment chronology, spanning the last 3400 years, is constructed by radiocarbon dating and time-stratigraphical correlation with the precisely dated Sofular Cave speleothem record. Yeniçağa sedimentary sequence contains 11 seismically induced event deposits characterized by siliciclastic-enriched intervals. Some of the event deposits are also associated with implications of sudden lake deepening, which may be related to coseismic subsidence. The paleoearthquake series having an average recurrence interval of ca. 260 years are interrupted by two possible seismic gaps of ca. 420 and 540 years. [less ▲]

Detailed reference viewed: 40 (14 ULg)
Peer Reviewed
See detailA 3400 year lacustrine paleoseismic record from the North Anatolian Fault, Turkey: Implications for bimodal recurrence behavior
Avsar, Ulas; Hubert, Aurelia ULg; De Batist, Marc et al

in Geophysical Research Letters (2014), 41(2), 377-384

High-resolution physical, geochemical, and geochronological analyses on the sedimentary sequence of Yeniçağa Lake, located in a fault-bounded basin along the North Anatolian Fault, reveal fingerprints of ... [more ▼]

High-resolution physical, geochemical, and geochronological analyses on the sedimentary sequence of Yeniçağa Lake, located in a fault-bounded basin along the North Anatolian Fault, reveal fingerprints of paleoearthquakes. A robust sediment chronology, spanning the last 3400 years, is constructed by radiocarbon dating and time-stratigraphical correlation with the precisely dated Sofular Cave speleothem record. Yeniçağa sedimentary sequence contains 11 seismically induced event deposits characterized by siliciclastic-enriched intervals. Some of the event deposits are also associated with implications of sudden lake deepening, which may be related to coseismic subsidence. The paleoearthquake series having an average recurrence interval of ca. 260 years are interrupted by two possible seismic gaps of ca. 420 and 540 years. [less ▲]

Detailed reference viewed: 40 (14 ULg)
Peer Reviewed
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 ▲]

Detailed reference viewed: 26 (2 ULg)
Peer Reviewed
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 ▲]

Detailed reference viewed: 14 (2 ULg)
See detailSea floor morphology of north-western Gulf of Corinth (Greece): combined impacts of Late Quaternary eustatism and active tectonics
Beckers, Arnaud ULg; Beck, Christian; Hubert, Aurelia ULg et al

Conference (2013, August 27)

Two high-resolution seismic reflection surveys (single channel sparker) were performed in the western part of the Gulf of Corinth. aboard HCMR’s R/V ALKYON, within the frame of SISCOR ANR Project. This ... [more ▼]

Two high-resolution seismic reflection surveys (single channel sparker) were performed in the western part of the Gulf of Corinth. aboard HCMR’s R/V ALKYON, within the frame of SISCOR ANR Project. This intra-continental marine basin is related to Late Cenozoic to Present extension separating “continental” Greece from Peloponnese. The connection of this active rift with the Ionian Sea (Mediterranean) is nowadays a 62 m deep sill, a situation which implies possible separations during low stands of global sea level, especially the last ones (MIS 2 and MIS 6). The western part of the Gulf, which is the most seismo-tectonically active part, appears as a transfer zone with both normal and strike slip faulting, identified through a dense grid of seismic lines. As a consequence, the offshore northern edge between the Mornos River delta and the Trizonia island shows a complex morphology due to the interaction between these structures, huge terrigenous feeding, deltaic development and sediment failures. Pre-Quaternary basement (Hellenids) was partly submitted to aerial erosion and paleodeltas are superimposed on the induced relief, visible at a depth of 110 m below Present sea level. The paleovalleys are filled with onlapping layered sediments, affected by several WSW-ENE and W-E oriented faults, part of them still active. An attempt to decipher both sources of relief genesis and evolution is presented. Beside, location and slip rate of active faults are discussed. [less ▲]

Detailed reference viewed: 41 (6 ULg)
See detailHigh energy environment offshore deposits in the western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Mortier, Clément; Beck, Christian et al

Conference (2013, April)

Detailed reference viewed: 48 (13 ULg)
See detailSedimentation and active faulting in the western tip of the Gulf of Corinth, Greece
Beckers, Arnaud ULg; Bodeux, Sarah; Beck, Christian et al

Conference (2013, March 06)

The Gulf of Corinth is one of the fastest-spreading intracontinental rift on Earth, a 120km long E-W structure propagating westward toward the Aegean subduction zone. Present day kinematics (GPS data ... [more ▼]

The Gulf of Corinth is one of the fastest-spreading intracontinental rift on Earth, a 120km long E-W structure propagating westward toward the Aegean subduction zone. 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. The high extension rate in the western part of the rift would imply a high seismic hazard if faults are not creeping. Our work concerns this western extremity of the Gulf of Corinth, for which we propose an accurate map of submarine faults as well as first chronostratigraphic interpretations. 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. We identified last glacial maximum (LGM) lowstand erosion surfaces along the northern coast. They made possible the mapping of post-LGM sediment thickness as well as estimates of subsidence rates. 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. Seafloor erosion is observed on 7.5 km2 in the western part, involving action of marine currents. The northern coast is subsiding between 1.7 and 2.2 mm y-1. We also mapped the following fault network described from east to west. 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 is 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. In the southern part of the rift, no fault has been observed between the Psatopyrgos fault bounding the southern side of the Gulf and the Mornos Delta. To the West, between the Mornos Delta and the Rion Straits, three main south dipping, normal and oblique faults have been identified. This NE-SW striking fault system could be part of a local transfer zone linking the Patras and the Corinth Basins, or of the NE-SW right-lateral slip fault system interconnecting the Gulf of Corinth to the Kephalonia transform Fault and the Hellenic subduction. [less ▲]

Detailed reference viewed: 54 (7 ULg)
See detailComparing the paleoseismic record obtained by coring a sag-pond and by classical trenching along the eastern segment of the North Anatolian Fault
Hubert, Aurelia ULg; Avsar, Ulas; Fraser, Jeef et al

Conference (2012, October)

Shallow lakes along minor structural bends or discontinuities of strike-slip fault are not usually paleoseismological target sites. In the present talk we show that a 2m deep, 700m long lake crosscut by ... [more ▼]

Shallow lakes along minor structural bends or discontinuities of strike-slip fault are not usually paleoseismological target sites. In the present talk we show that a 2m deep, 700m long lake crosscut by the eastern segment of the North Anatolian Fault contains a reliable paleoseimological record obtained through coring. The North Anatolian Fault, a major strike-slip fault in Turkey, last ruptured across the Aşağıtepecik Lake in 1939 with a slip of about 6 m. Seismic lines still show remains of the fault rupture forming minor scarps across the lake. Collected short cores display a set of sedimentary sequences. Each sequence is composed of similar organic rich sedimentary units. The lower unit is dark and fibrous, and is similar to the present sedimentation at the top of the core. The upper unit is disturbed and has anomalous organic matter content, grain size and mineralogy. It is interpreted as an earthquake induced sedimentary event. The 2.5 m long AT2007LG core comprises four sequences, and four sedimentary events. Radiogenic 210Pb and 137Cs data obtained in Boes et al. (2009) imply that the shallowest event 1 was triggered by the 1939 M=7.9 Erzincan earthquake. Radiocarbon dating suggest that events 2 and 4 were initiated by the 1668 and 1254 historical earthquakes. The event 3 does not correspond to a large historical earthquake on the NAF. The record can be compared to a classical paleoseismological study located about 2.5 km more to the east. The investigation comprised three paleoseismic trenches located along about 2km of the principal fault strand. Trench T1 revealed clear evidence for one earthquake interpreted to be the 1939 Erzincan earthquake. Trench T2 revealed evidence of three earthquakes. Trench T3 revealed a record of colluvial wedges that interfinger with fine-grained inter-fan deposits. We interpreted a sequence of six earthquake event horizons including the 1939 Erzincan earthquake. The first three earthquakes are correlated to historical earthquakes in A.D. 1668, 1254, 499 and two further events were identified at 881 – 673 B.C. and 1406 – 1291 B.C. (2σ age ranges). By comparing all available earthquake timing studies,we conclude that the 1939 earthquake segment does not always rupture in unison. [less ▲]

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