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See detailSedimentation influx and volcanic interactions in the Fuji Five Lakes: implications for paleoseismological records
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Yamamoto, Shinya et al

Conference (2017, April 27)

The Fuji Fives Lakes are located at the foot of Mount Fuji volcano close to the triple junction, where the North American Plate, the Eurasian plate and the Philippine Sea Plate meet. These lakes are ... [more ▼]

The Fuji Fives Lakes are located at the foot of Mount Fuji volcano close to the triple junction, where the North American Plate, the Eurasian plate and the Philippine Sea Plate meet. These lakes are ideally situated to study Mount Fuji volcanism and the interaction between volcanism, changes in lake sedimentation rates and the ability of lakes to record paleoearthquakes. Here, we present newly acquired geological data of Lake Yamanaka and Lake Motosu, including seismic reflection profiles, gravity and piston cores. These two lakes and their respective watersheds were affected by several eruptions of Mount Fuji. Lake Yamanaka, a very shallow lake (max. depth 14 m), was heavily impacted by the scoria fall-out of the A.D. 1707 Hoei eruption of Mount Fuji. A detailed investigation of the effect of the Hoei eruption was conducted on short gravity cores, using high resolution XRD, C/N and 210Pb/137Cs analyses. The preliminary results suggest that the sedimentation rate of Lake Yamanaka drastically reduced after the Hoei eruption, followed by an increase until the present day. Similarly, lacustrine sedimentation in Lake Motosu (max. depth 122 m) was disturbed by Mount Fuji volcanism at a larger scale. The watershed of Lake Motosu was impacted by several lava flows and scoria cones. For example, the Omuro scoria cone reduced the catchment size of Lake Motosu and modified its physiography. The related scoria fall out covered an extensive part of the lake catchment and reduced terrigenous sedimentary influx to Lake Motosu. Within the deep basin of Lake Motosu, seismic reflection data shows two different periods that are distinguished by a major change in the dominant sedimentary processes. During the first period, sublacustrine landslides and turbidity currents were the dominant sedimentation processes. During the second one, the seismic stratigraphy evidences only deposition of numerous turbidites interrupting the hemipelagic sedimentation. Changes in sedimentary processes can be linked to the modification of the lake watershed by Mount Fuji volcanism, leading to a decrease in the sediment volume that can be remobilized, and therefore disappearance of large sublacustrine landslides. Turbidites are deposited due to surficial remobilization of lake slope sediments most probably as a result of earthquake shaking. When studying sedimentological records of lakes to define the paleoearthquake record, eruptions of nearby volcanoes should be taken into account. This study suggests that a large magnitude earthquake occurring few decades after a volcanic eruption (with large scale scoria fall-out), might not be recorded in a lake, or would only be fingerprinted in the sedimentary record by small turbiditic flows. References: Miyaji N., Kan'no A., Kanamaru T., Mannen K. 2011. High-resolution reconstruction of the Hoei eruption (AD 1707) of Fuji volcano, Japan. Journal of Volcanology and Geothermal Research 207, 113–129. [less ▲]

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See detailThe role of natural hazards and human activities on change of sedimentation patterns: The case of Lake Yamanaka (Fuji Five Lakes, Japan)
Lamair, Laura ULiege; Hubert, Aurelia ULiege; El Ouahabi, Meriam ULiege et al

Conference (2017, April 10)

The last eruption of Mt Fuji (Japan) occurred in A.D. 1707. The eruption lasted 16 days from 16 December 1707 to 1 January 1708 (Tsuya, 1955) and 1.8 km3 of volcanic materials were ejected in total ... [more ▼]

The last eruption of Mt Fuji (Japan) occurred in A.D. 1707. The eruption lasted 16 days from 16 December 1707 to 1 January 1708 (Tsuya, 1955) and 1.8 km3 of volcanic materials were ejected in total (Miyaji et al., 2011). Lake Yamanaka, a very shallow lake (max. 14. 3 m depth) located at the foot of the east-north-eastern flank of Mt Fuji, was heavily impacted by the eruption. A thick scoria layer entirely covered the catchment of Lake Yamanaka. The thickness of the deposit varies from 5 to 37 cm around Lake Yamanaka and reaches up to 149 cm at the south-west extremity of the catchment (Miyaji et al., 2011). In order to study the influence of Hoei eruption on Lake Yamanaka, 5 gravity cores were taken during the 2014 QuakeRecNankai campaign. The Hoei scoria was present at the bottom of the one core and in the core catcher of the four other cores. High resolution magnetic susceptibility, XRD, XRF, LOI, C/N and 210Pb/137Cs analyses were performed on the gravity cores. The results shows three distinct periods of sedimentation: (1) From Hoei eruption to A.D. 1900; (2) From A.D. 1900 to A.D. 1990; (3) From A.D. 1990 to A.D. 2014. The first period is characterized by a very low sedimentation rate (~0.07 cm/yr). During this period, the sediments of the catchment were trapped below the thick Hoei scoria layer. However, peaks of terrigenous input are recorded. We link such detrical signals with violent typhoons that hit the Fuji Five Lakes region. The water from the heavy rains percolated through the porous thick scoria layer and saturated it. As a result, surface runoffs carried the sediments from the catchment into Lake Yamanaka. The second period (from A.D. 1900 to A.D. 1990) is defined by an increase of the sedimentation rate (~0.16 cm/yr). The development of soil and the agriculture (e.g. pastureland, rice field, mulberry plantations) reduced the impact of Hoei scoria. The terrigenous inputs are higher than previously but remained more or less constant during this period of time. As the thickness of the scoria layer is partially reduced or covered by new soil, rains triggered by smaller typhoons could drain the sediments from watershed and transport them into the lake. The most recent period representing the last 27 years is characterized by a very high sedimentation rate (~1.036 cm/yr). The transition between period 2 and period 3 corresponds to the development of mass tourism and the urbanization around Lake Yamanaka. It is marked by an increasing of atmospheric pollution (Pb, Zn). In the upper part of the cores, a peak of 137Cs is observed. Such peak is related to cesium fall-out after Fukushima incident in 2011. In addition to the fingerprint of human impact, the lake also record a terrigenous signal related to the 2007 Fitow typhoon which provoked damage in the area. This study highlights the influence of eruptions and typhoons on the sedimentation of Lake Yamanaka. In the present day, the sedimentation recovery after a major eruption is accelerated by human activity. References: Miyaji N., Kan'no A., Kanamaru T., Mannen K. 2011. High-resolution reconstruction of the Hoei eruption (AD 1707) of Fuji volcano, Japan. Journal of Volcanology and Geothermal Research 207, 113–129. Tsuya, H. 1955. Geological and petrological studies of volcano, Fuji, V.: 5. on the 1707 eruption of Volcano Fuji. Bulletin of the Earthquake Research Institute 33, 341–383. [less ▲]

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See detailA history of mass transport complexes related to eruptions and earthquake shaking: the case of Lake Motosu (Japan).
Lamair, Laura ULiege; Hubert, Aurelia ULiege; El Ouahabi, Meriam ULiege et al

Conference (2016, March 04)

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five ... [more ▼]

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five Lakes, located at the eastern end of the Nankai-Suruga Trough. Here, we present results from Lake Motosu, the deepest of the Fuji Five Lakes (max. depth 122 m), including seismic reflection profiles, gravity cores and preliminary results of 6.8 m long piston core. We identify mass transport deposits and turbidites possibly triggered by earthquakes. We study the lake sedimentary architecture and the Holocene sedimentation with a high resolution GEOPULSE pinger system. A seismic grid with total length of 39 km covered the lake. We identify a specific seismic horizon that may be related to the Aokigaraharamarubi lava flow (864 A.D.). Strong reflectors may also correlate with tephra layers from Oniwa-Okuniwa eruptions (620-790 A.D). In the western part of the lake, the seismic reflection profile reveals a change after the proposed Oniwa-Okuniwa eruptions in terms of volume and length of mass transport deposits. Large mass-transport deposits occurring before the eruptions are characterized by chaotic seismic facies. After the eruptions, the mass-transport deposits are much smaller and are characterized by transparent seismic facies attributed to turbiditic flow. Six gravity cores (max. 90cm long) provide samples of the lake bottom sediments. In these cores, turbidites and megaturbidites were identified based on facies analyses, combined with X-ray scanning, geophysical properties, grain-size analysis, mineralogy and XRF. During the period between the Oniwa-Okuniwa eruptions and the Aokigaraharamarubi lava flow (620-864 A.D), several lava flows occurred in the northern part of Mount Fuji and drastically modified the catchment of Lake Motosu. The decreasing of the size of catchment led to a decreasing of sedimentary yield in the lake. The change in the sedimentation rate could partly explain why we have a change in the type of mass transport deposit. Additionally, analyses were performed to define the minimum shaking intensity required to destabilize the slope. To assess slope stability, we investigated the clay content and the clay mineralogy of samples taken along the slope. In this presentation, we discuss the link between eruptions of Mount Fuji, decreasing of the size of the catchment, sedimentation rate and earthquake shaking. [less ▲]

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See detailA history of mass transport complexes related to earthquake shaking: the case of Lake Motosu (Japan).
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Boes, Evelien et al

Poster (2016, January 27)

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five ... [more ▼]

The QuakeRecNankai project focuses on geological records of paleoearthquakes along the Nankai-Suruga subduction zone, south central Japan. In the framework of the project, we investigated the Fuji Five Lakes, located at the eastern end of the Nankai-Suruga Trough. Here, we present results from Lake Motosu, the deepest of the Fuji Five Lakes (max. depth 122 m), including seismic reflection profiles and gravity cores. We identify mass transport deposits and turbidites possibly triggered by earthquakes. We study the lake sedimentary architecture and the Holocene sedimentation with a very high resolution GEOPULSE pinger system. A seismic grid with total length of 39 km covered the lake. We identify a specific seismic horizon that may be related to the Aokigaraharamarubi lava flow (864 A.D.). Strong reflectors may also correlate with tephra layers from Oniwa-Okuniwa eruptions (620-790 A.D). In the western part of the lake, the seismic reflection profile reveals a change after the proposed Oniwa-Okuniwa eruptions in terms of volume and length of mass transport deposits. Large mass-transport deposits occurring before the eruptions are characterized by chaotic seismic facies. After the eruptions, the mass-transport deposits are much smaller than previously and characterized by transparent seismic facies attributed to a turbiditic flow. Six gravity cores (max. 90cm) provide samples of the lake bottom sediments. In these cores, turbidites were identified based on facies analyses, combined with X-ray scanning, geophysical properties, grain-size analysis, mineralogy and XRF. An age-depth model was established based on radionuclide dating. We compare the timing of sedimentary events in Lake Motosu with a historical catalogue of natural hazards in the Fuji Five Lakes area, including historical records of megathrust earthquakes rupturing the Nankai subduction zone, the Sagami Trough and other earthquakes occurring along inland faults. Several analyses were performed to understand why we have a change in type of mass transport deposit after the eruptions and to define the minimum shaking intensity required to destabilize the slope. To assess slope stability, we investigated the clay content and the clay mineralogy of the slope. Spatial statistics was also performed in order to evaluate the degree of the slope and the accumulation of sediment. We suggest that the presence of a scoria layer might have contributed to slope destabilization. [less ▲]

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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 ULiege; Beck, Christian; Hubert, Aurelia ULiege et al

in Marine Geology (2016)

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 detailGeological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan
Garett, Ed; Fujiwara, Osamu; Garrett, Philip et al

in Geophysical Research Abstracts (2016)

The Nankai-Suruga Trough, lying immediately south of Japan’s densely populated and highly industrialised southern coastline, generates devastating great earthquakes (magnitude > 8). Intense shaking ... [more ▼]

The Nankai-Suruga Trough, lying immediately south of Japan’s densely populated and highly industrialised southern coastline, generates devastating great earthquakes (magnitude > 8). Intense shaking, crustal deformation and tsunami generation accompany these ruptures. Forecasting the hazards associated with future earthquakes along this >700 km long fault requires a comprehensive understanding of past fault behaviour. While the region benefits from a long and detailed historical record, palaeoseismology has the potential to provide a longer-term perspective and additional insights. Here, we summarise the current state of knowledge regarding geological evidence for past earthquakes and tsunamis, incorporating literature originally published in both Japanese and English. This evidence comes from a wide variety of sources, including uplifted marine terraces and biota, marine and lacustrine turbidites, liquefaction features, subsided marshes and tsunami deposits in coastal lakes and lowlands. We enhance available results with new age modelling approaches. While publications describe proposed evidence from > 70 sites, only a limited number provide compelling, well-dated evidence. The best available records allow us to map the most likely rupture zones of eleven earthquakes occurring during the historical period. Our spatiotemporal compilation suggests the AD 1707 earthquake ruptured almost the full length of the subduction zone and that earthquakes in AD 1361 and 684 were predecessors of similar magnitude. Intervening earthquakes were of lesser magnitude, highlighting variability in rupture mode. Recurrence intervals for ruptures of the a single seismic segment range from less than 100 to more than 450 years during the historical period. Over longer timescales, palaeoseismic evidence suggests intervals ranging from 100 to 700 years. However, these figures reflect thresholds of evidence creation and preservation as well as genuine recurrence intervals. At present, we have not identified any geological data that support the occurrence earthquakes of larger magnitude than that experienced in AD 1707; however, few published studies seek to establish the relative magnitudes of different earthquake and tsunami events. Alongside the paucity of research designed to quantify the magnitude of past earthquakes, we emphasise a number of other issues, including alternative hypotheses for proposed palaeoseismic evidence, the lack of robust chronological frameworks and insufficient appreciation of changing thresholds of evidence creation and preservation over time. These key issues must be addressed by future research. [less ▲]

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See detailCharacteristics and frequency of large submarine landslides at the western tip of the Gulf of Corinth
Beckers, Arnaud; Hubert, Aurelia ULiege; Beck, Christian et al

in Geophysical Research Abstracts (2016), 18

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See detailSedimentary records of past earthquakes in Boraboy Lake during the last ca 600 years (North Anatolian Fault, Turkey).
Avsar, Ulas; Hubert, Aurélia ULiege; De Batist, Marc et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2015), (433), 1-9

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See detailActive faulting at the western tip of the Gulf of Corinth, Greece, from high-resolution seismic data
Beckers, Arnaud ULiege; Hubert, Aurelia ULiege; 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 detailEarthquake imprints on 400 years of marine sedimentation in the western Gulf of Corinth, Greece
Beckers, Arnaud ULiege; Hubert, Aurelia ULiege; 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 detailSpatiotemporal distribution of last 500 yrs turbidites in the Western Gulf of Corinth, Greece: implications for the characterization of historical earthquakes
Beckers, Arnaud ULiege; Hubert, Aurelia ULiege; 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 detailPaléosismologie marine et failles actives dans le golfe de Corinthe (Grèce)
Beckers, Arnaud ULiege; Beck, Christian; Hubert, Aurelia ULiege 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 ULiege; Hubert, Aurelia ULiege; 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 detailA 3400 year lacustrine paleoseismic record from the North Anatolian Fault, Turkey: Implications for bimodal recurrence behavior
Avsar, Ulas; Hubert, Aurelia ULiege; 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 ▲]

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See detailSeismically-triggered organic-rich layers in recent sediments from lake Gollukoy (North Anatolian Fault, Turkey
Avşar, Ulaş; Hubert, Aurelia ULiege; De Batist, Marc et al

in Quaternary Science Reviews (2014), 103

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See detailSea floor morphology of north-western Gulf of Corinth (Greece): combined impacts of Late Quaternary eustatism and active tectonics
Beckers, Arnaud ULiege; Beck, Christian; Hubert, Aurelia ULiege 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 ▲]

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See detailDeformation pattern at the western tip of the Corinth Rift
Beckers, Arnaud ULiege; Hubert, Aurelia ULiege; Beck, Christian et al

Conference (2012, September)

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip ... [more ▼]

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip. The style of extension and strain distribution is well documented offshore in the eastern and central parts of the rift (Bell, 2009). At its most active western extremity, published offshore data is not sufficient to characterize the deformation pattern. High resolution seismic profiles were thus acquired in that region within the framework of the SISCOR project to improve our understanding of fault evolution, seismicity and to be able to construct mechanical models of deformation. Here we investigate the spatio-temporal pattern of the basin subsidence and deposition with sparker data acquired in November 2011. Active faults and correlative time horizons were first mapped. The stratigraphy was then correlated with the eustatic sea-level curve. This sequence stratigraphic interpretation is possible because there are strong glacial-interglacial variations in the depositional environment. In fact lacustrine conditions prevail within the gulf during glacio-eustatic lowstands and are characterized by low amplitudes seismic facies. So synrift sediment isopachs over the last 12 000 and 130 000 yrs could be produced. The interpreted data allow us to: (1) compare deformation pattern at the western tip of the Gulf with the more mature central and eastern part of the Rift; (2) constrain the pattern and the timing of deformation as well as rates of faulting. Reference Bell, R. E., McNeill, L. C., Bull, J. M., Henstock, T. J., Collier, R. E. L., & Leeder, M. R., 2009. Fault architecture, basin structure and evolution of the Gulf of Corinth Rift, central Greece. Basin Research, 21(6), 824-855. doi:10.1111/j.1365-2117.2009.00401.x [less ▲]

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See detailSedimentological fingerprints of paleoseimic activity revealed from lake sediments: a case study from the North Anatolian Fault (NAF), Turkey
Avsar, Ulas; Hubert, Aurelia ULiege; Fagel, Nathalie ULiege et al

in Abstracts with Programs - Geological Society of America (2010, October)

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See detailBulk organic geochemistry of sediments from Puyehue Lake and its watershed (Chile, 40°S): Implications for paleoenvironmental reconstructions
Bertrand, Sébastien; Sterken, Mieke; Vargas-Ramirez, Lourdes et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2010), 294

Since the last deglaciation, the mid-latitudes of the southern Hemisphere have undergone considerable environmental changes. In order to better understand the response of continental ecosystems to ... [more ▼]

Since the last deglaciation, the mid-latitudes of the southern Hemisphere have undergone considerable environmental changes. In order to better understand the response of continental ecosystems to paleoclimate changes in southern South America, we investigated the sedimentary record of Puyehue Lake, located in the western piedmont of the Andes in South-Central Chile (40°S). We analyzed the elemental (C, N) and stable isotopic ([delta]13C, [delta]15N) composition of the sedimentary organic matter preserved in the lake and its watershed to estimate the relative changes in the sources of sedimentary organic carbon through space and time. The geochemical signature of the aquatic and terrestrial end-members was determined on samples of lake particulate organic matter (N/C: 0.130) and Holocene paleosols (N/C: 0.069), respectively. A simple mixing equation based on the N/C ratio of these end-members was then used to estimate the fraction of terrestrial carbon ([latin small letter f with hook]T) preserved in the lake sediments. Our approach was validated using surface sediment samples, which show a strong relation between [latin small letter f with hook]T and distance to the main rivers and to the shore. We further applied this equation to an 11.22 m long sediment core to reconstruct paleoenvironmental changes in Puyehue Lake and its watershed during the last 17.9 kyr. Our data provide evidence for a first warming pulse at 17.3 cal kyr BP, which triggered a rapid increase in lake diatom productivity, lagging the start of a similar increase in sea surface temperature (SST) off Chile by 1500 years. This delay is best explained by the presence of a large glacier in the lake watershed, which delayed the response time of the terrestrial proxies and limited the concomitant expansion of the vegetation in the lake watershed (low [latin small letter f with hook]T). A second warming pulse at 12.8 cal kyr BP is inferred from an increase in lake productivity and a major expansion of the vegetation in the lake watershed, demonstrating that the Puyehue glacier had considerably retreated from the watershed. This second warming pulse is synchronous with a 2 °C increase in SST off the coast of Chile, and its timing corresponds to the beginning of the Younger Dryas Chronozone. These results contribute to the mounting evidence that the climate in the mid-latitudes of the southern Hemisphere was warming during the Younger Dryas Chronozone, in agreement with the bipolar see-saw hypothesis. [less ▲]

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See detailThe Earthquake Sedimentary record of The Lake Hazar along the East Anatolian Fault in Turkey
Boes, Xavier; Hubert, Aurelia ULiege; Garcia, David et al

in Geophysical Research Abstracts (2009, April), 11

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