Publications of Aurelia Hubert
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See detailNatural hazards recorded in the Fuji Five Lakes: earthquake shaking, typhoon induced flooding and volcanic eruptions ral hazards recorded in the Fuji Five Lakes: earthquake shaking, typhoon induced flooding and volcanic eruptions
Hubert, Aurelia ULiege; Lamair, Laura ULiege; Yamamoto, Shinya et al

Conference (2018, May)

The 2014-2018 QuakeRecNankai project (acronym for "Paleo-tsunami and earthquake records of ruptures along the Nankai Trough, offshore South-Central Japan") funded by the Belgium Sciences Policy Office ... [more ▼]

The 2014-2018 QuakeRecNankai project (acronym for "Paleo-tsunami and earthquake records of ruptures along the Nankai Trough, offshore South-Central Japan") funded by the Belgium Sciences Policy Office focuses on the Fuji Five Lake area (central Japan) with the aim of a better understanding of the spatial and temporal recurrence of natural disasters. The region is susceptible to be impacted by natural hazards such as earthquake shaking, typhoon-induced floods and volcanic eruptions. The study location for natural hazard disaster is highly relevant since Mt. Fuji and the Fuji Five Lakes were recognized as a world heritage site in 2013 with about 300 000 tourists visiting the area every year. Within the framework of the project, the lacustrine sediments from Lake Motosu, Lake Sai and Lake Yamanaka were investigated and used to reconstruct the natural hazard history of the region. In the sedimentary infill of Lake Motosu, mass-transport deposits and turbidites triggered by earthquakes were recorded. Over the last ca. 6000 years, the mean recurrence time of seismic event triggering turbidites in Lake Motosu is 184±8 years. A comparison between the age of the turbidites and historical and paleoseismological records suggest that earthquake shaking impacting the Fuji Five Lakes area can be attributed mostly to large magnitude earthquakes occurring along the Sagami trench or along the Nankai-Suruga Subduction Zone. The two most recent earthquakes occurring along these subduction zones (i.e., the 1944 Showa Tonankai and the 1923 Kanto earthquakes) were recorded. By contrast with the sedimentary record of Lake Motosu, the lacustrine sediments collected in Lake Sai are a good archive for flood events. Detrital layers associated with the debris flow triggered by the 1966 Typhoon Ida (189 killed people, 3.9 millions yens damages) were identified, as well as other flood events associated with extreme precipitation events. Regarding volcanic eruptions, Lake Yamanaka and its catchment were repeatedly impacted by scoria fall-out due to their proximity to the Mt. Fuji volcano and the westerly wind direction . The last eruption (Hoei, A.D. 1707) strongly affected the lacustrine sedimentation and has a long-term effect on the catchment and on the lake, due to the sealing of the underlying sediments by the thick scoria layer. The geolimnology study of the Fuji Five Lakes gave us a better comprehension of the long-term recurrence of natural hazards affecting the region as well as their effects on the environment. [less ▲]

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See detailKarstic hazard assessment combining geomorphological and geological data in the region of BOUKADIR (Chlef, Algeria)
Moulana, Meriem Lina ULiege; Guendouz, Mostefa; Hubert, Aurelia ULiege

Poster (2018, April 13)

In 1988, a large collapse crater of 60m in diameter and 35m of deep occurred in the national road RN4 linking the wilaya of Algiers to Oran, exactly in the region of Boukadir located in the northern ... [more ▼]

In 1988, a large collapse crater of 60m in diameter and 35m of deep occurred in the national road RN4 linking the wilaya of Algiers to Oran, exactly in the region of Boukadir located in the northern piedmont of Ouarsenis in Algeria. The cover collapse sinkhole is located in the Boukadir plain, where the Chlef river is running, at the foot of the 723m high Oursenis Mt, composed of Lithothamnion limestones of the Messinian (uppermost stage of the Miocene). In Algeria, there are many karst areas like Tlemcen (karstification well developed at depth), Saida (karstification well developed at the surface), or the calcareous ridge of Djurdjura, Jijel... But the area of Boukadir has never been defined as a karstic region despite the 1988 sinkhole and the various karstic forms that we mapped in Oursenis Mt at the surface.We focus in this study on the Boukadir plain at the foot of the Oursenis range, where the carbonate rocks are covered by younger sediments, and where the infrastructures (RN4, highway from the east of Algeria to the West) and villages (Boukadir, 41,655 inhabitants) are located. To assess karstic hazard and related risk for the two major infractructures running at the foot of the Ouarsenis Mt, we combine geological, geomorphological and hydrological data. The examination of the geomorphology using aerial photographs, DEM and satellite images reveals the absence of any subsidence sinkhole, which is related to the fact that the covering sediments contain a significant amount of clay. Indeed the Lithothamnion limestones are covered by the marine marls of the Astien deposited during the Pliocene and clayey continental deposits of the Villafranchien formation (Upper Pliocene). The combination of surface geology with boreholes in the Boukadir plain reveals that the reef Lithothamnion limestsones does to extend across the Boukadir plain. The karstic hazard is thus restricted to a 2km wide narrow band at the foot of the Oursenis Mt. [less ▲]

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See detailKarstic Hazard in BOUKADIR (Chlef-Algeria) and its potential socio-economic impact
Moulana, Meriem Lina ULiege; Guendouz, Mostefa; Hubert, Aurelia ULiege

Conference (2018, March 16)

Boukadir, the municipality of the Wilaya of Chlef located west of Algiers has never been defined as a karstic region of Algeria despite the formation of a large collapse sinkhole in June 1988. The ... [more ▼]

Boukadir, the municipality of the Wilaya of Chlef located west of Algiers has never been defined as a karstic region of Algeria despite the formation of a large collapse sinkhole in June 1988. The sinkhole formed a crater with 60m wide and 35 m deep across the national road RN4 linking the Wilaya of Algiers to Oran. The municipality of Boukadir is located near southern edge of a 20 km wide plain flooded by the Chlef River bounded to the south by the Ouarsenis mountain range. The northern piedmont of the Ouarsenis Range is composed of Lithothamnion limestones of the tertiary that form a 25° dipping structural surface. Traces of karstification were founded in these Lithothamnion limestones outcropping at the surface. At the level of the plain and of the collapse sinkhole, the carbonate rocks are covered with younger sediments (quaternary alluviums). In order to objectively evaluate the hazard in the covered karst, we combine a range of boreholes to unravel the geometry of the carbonates and its cover. The characteristics of the limestones are evaluated combining XRD, XRF and thin sections in order to evaluate its dissolution potential. The socio-economic context is reviewed (population, industry, agriculture...) to discuss the karstic risk. [less ▲]

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See detailInter-techniques comparison of PIXE and XRF for Lake sediments
El Ouahabi, Meriam ULiege; Chene, Grégoire ULiege; Strivay, David ULiege et al

in Journal of Analytical Atomic Spectrometry (2018), 33(883 - 892),

In this paper we describe a validation procedure for chemical analysis of major elements and some minor elements as Sr, Cr, Ni, Zn and Zr in heterogeneous geological sediments. The procedure applies two ... [more ▼]

In this paper we describe a validation procedure for chemical analysis of major elements and some minor elements as Sr, Cr, Ni, Zn and Zr in heterogeneous geological sediments. The procedure applies two distinct techniques (PIXE and XRF) to the analysis of sediments. In this work an inter-technique comparison of the heterogeneous lacustrine sediments from the Amik Lake in the vicinity of the Roman city of Antioch (SE, Turkey) was carried out. Dried raw samples and with the addition of linking powder were analyzed using PIXE performed on the “Arkeo” beam line of the University of Liège AVF-Cyclotron and XRF (University of Liège). The aim of this work was to compare PIXE and XRF analysis with the set-ups routinely in use in the two laboratories. The purpose was also to determine the best combination of techniques and sample preparation protocol to be applied for heterogeneous sediments and the main elements of interest for each specific technique. The results are in agreement among the two techniques, with discrepancies concerning almost lighter and minor elements. These differences are related mainly to the texture of the sediments and the intrinsic features of the XRF and PIXE techniques. Major and selected minor elements are sensitive to the grain-size and the porosity of the samples. However, the accuracy of both XRF and PIXE requires the reduction of the grain-size or addition of linking powder to the sediments to fill the voids in order to increase the intensities of both lighter and minor elements. The results demonstrate the critical importance of sample treatment prior to analysis as well as the necessity of several measurement points and replicates to ensure the accuracy of the PIXE results. [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 Natural Hazards and Earth System Sciences (2018)

Coastal and submarine landslides are frequent at the western tip of the Gulf of Corinth, where small to medium failure events (106–107 m3/ occur on average every 30–50 years. These landslides trigger ... [more ▼]

Coastal and submarine landslides are frequent at the western tip of the Gulf of Corinth, where small to medium failure events (106–107 m3/ occur on average every 30–50 years. These landslides trigger tsunamis and consequently represent a significant hazard. We use here a dense grid of high-resolution seismic profiles to realize an inventory of the large mass transport deposits (MTDs) that result from these submarine landslides. Six large mass wasting events are identified, and their associated deposits locally represent 30% of the sedimentation since 130 ka in the main western basin. In the case of a large MTD of 1 km3 volume, the simultaneous occurrence of different slope failures is inferred and suggests an earthquake triggering. However, the overall temporal distribution of MTDs would result from the time-dependent evolution of pre-conditioning factors rather than from the recurrence of external triggers. Two likely main pre-conditioning factors are (1) the reloading time of slopes, which varied with the sedimentation rate, and (2) dramatic changes in water depth and water circulation that occurred 10–12 ka ago during the last post-glacial transgression. Such sliding events likely generated large tsunami waves in the whole Gulf of Corinth, possibly larger than those reported in historical sources considering the observed volume of the MTDs. [less ▲]

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See detailNumerical investigation on the seismic performance of aqueduct bridge structures: application to the Antioch on the Orontes Aqueduct (Antakya, Turkey)
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Degée, Hervé et al

E-print/Working paper (2018)

Seismic shaking can damage building, especially historical structures which were not designed with building codes. Here we focus on Roman aqueduct bridge structures, which remains can be found all over ... [more ▼]

Seismic shaking can damage building, especially historical structures which were not designed with building codes. Here we focus on Roman aqueduct bridge structures, which remains can be found all over the Mediterranean area, a highly seismic region. We developed simple models using a finite element software to realize static and dynamic linear analyses of these structures when they are subject to imposed ground motion. The effects of basic variations in the pier-arch architectural design and in the type of material used were investigated. We identified two main weak zones: the arch extremities and the bottom part of the piers. The damage occurrence in these two areas could be attributed to earthquake shaking. Our first-order vulnerability analysis also points to different ways to enhance the structure stability: building narrow arches, adding buttress zones and using bricks which are light materials. Finally, we also investigated the vulnerability to seismic shaking of a real case example, the Antioch on the Orontes Aqueduct in Harbiye (Turkey). The aqueduct shows different stages of constructions, damage areas and repairs. The modeling suggests that the observed damages were the results of earthquake shaking. The repairs reinforced the structure and stabilized it pointing to the adaptive technology and skills of the roman engineers. [less ▲]

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See detailLate Holocene changes on erosion pattern on a lacustrine environment: landscape stabilization by volcanic activity versus human activity
Lamair, Laura ULiege; Hubert, Aurelia ULiege; El Ouahabi, Meriam ULiege et al

in Geochemistry, Geophysics, Geosystems (G3) (2018)

The most recent eruption of Mt. Fuji (Japan), the VEI 5 Hōei plinian eruption (CE 1707) heavily impacted Lake Yamanaka, a shallow lake located at the foot of Mt. Fuji. Here, we discuss the influence of ... [more ▼]

The most recent eruption of Mt. Fuji (Japan), the VEI 5 Hōei plinian eruption (CE 1707) heavily impacted Lake Yamanaka, a shallow lake located at the foot of Mt. Fuji. Here, we discuss the influence of the Hōei eruption on the lacustrine sedimentation of Lake Yamanaka using high resolution geophysical and geochemical measurements on gravity cores. Hōei scoria fall-out had two major impacts on Lake Yamanaka: (i) reduction of the sedimentation rate (from ~0.16 cm/yr to ~0.09 cm/yr); and (ii) the increase of in-situ lake productivity. Sedimentation rates after the eruption were relatively low due to the thick scoria layer, trapping underlying sediments in the catchment. The lacustrine system took over more than ~170 years to begin to recover from the Hōei eruption: sedimentation recovery have been accelerated by changes in land use. Since the beginning of the 20th Century, vegetated strips delimited cultivated parcels, trapping sediment and minimizing the anthropogenic impacts on the sedimentation rate. Over the last decade, the decline of agriculture and the increase of other human activities led to an increase in the sedimentation rate (~1 cm/yr). This study highlights the effect of the grainsize of the volcanic ejecta on the sedimentation rate following a volcanic eruption. Coarse-grained tephra are difficult to erode. Therefore, their erosion and remobilization is largely limited to intense typhoons when porous scoria deposits are saturated by heavy rains. Moreover, this study suggests that recent anthropogenic modifications of the catchment had a greater impact on the sedimentation rate than the Hōei eruption. [less ▲]

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See detailHistorical Nankai-Suruga megathrust earthquakes recorded by tsunami and terrestrial mass movement deposits on the Shirasuka coastal lowlands, Shizuoka Prefecture, Japan
Garrett, Ed; Fujiwara, Osamu; Riedesel, Svenja et al

in Holocene (2018)

Geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records. In this paper, we present a multi-proxy ... [more ▼]

Geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records. In this paper, we present a multi-proxy investigation of a coastal lowland site facing the Nankai-Suruga megathrust and appraise evidence for tsunamis and earthquake-triggered terrestrial mass movements occurring over the last 800 years. Combining a high-resolution chronology with X-ray computed tomography and analyses of particle size, diatoms, pollen, non-pollen palynomorphs and aerial photographs, we present the most compelling geological evidence of the 1361 CE Kōan (also known as Shōhei) tsunami reported to date from any site along the megathrust. This finding is consistent with either of two recent hypotheses: a single larger rupture of both the Nankai and Tōnankai regions or two smaller ruptures separated by a few days. Enhancing the site chronology using Bayesian age modelling, we verify evidence for inundation during the 1498 CE Meiō tsunami. While previous investigations identified evidence for historically recorded tsunamis in 1605, 1707 and 1854 CE and a storm surge in 1680 or 1699 CE, we encountered a thick sand layer rather than discrete extreme wave deposits in this interval. The overprinting of evidence highlights the potential for geological records to underestimate the frequency of these events. A terrestrial mass movement also deposited a sand layer at the site; radionuclide dating and aerial photographs provide independent confirmation that this may have been triggered by intense shaking in 1944 CE during the most recent great Nankai-Suruga megathrust earthquake. [less ▲]

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See detailMt. Fuji Holocene eruption history reconstructed from proximal lake sediments and high-density radiocarbon dating
Obrochta, S. P.; Yokoyama, Y.; Yoshimoto, M. et al

in Quaternary Science Reviews (2018), 200

An 8000-year lacustrine sediment record from Lake Motosu (Fuji Five Lakes) records several eruptions, including potentially unreported events, of the active Mt. Fuji volcano, which receives approximately ... [more ▼]

An 8000-year lacustrine sediment record from Lake Motosu (Fuji Five Lakes) records several eruptions, including potentially unreported events, of the active Mt. Fuji volcano, which receives approximately 47 million annual visitors. A high-fidelity age model is constructed from tephra ages and high-density radiocarbon dating of terrestrial macrofossil and bulk organic matter. Variability in lake reservoir age is constrained by modern lake water radiocarbon measurement and reverse calibration of tephra calendar ages. We present more accurate ages for known eruptions, detect a wider distribution of ejecta for several eruptions, including the most recent summit eruption, and potentially identify previously undetected flank eruptions. There are closely spaced scoria-fall layers that may be difficult to differentiate as separate events in land-based surveys. These results demonstrate the utility of lacustrine sediments as powerful tools for understanding characteristics of volcanic eruptions. © 2018 Elsevier Ltd [less ▲]

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See detailVolcanic influence of Mt. Fuji on the watershed of Lake Motosu and its impact on the lacustrine sedimentary record
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Yamamoto, Shinya et al

in Sedimentary Geology (2018), 363

Lacustrine sediments are particularly sensitive to modifications within the lake catchment. In a volcanic area, sedimentation rates are directly affected by the history of the volcano and its eruptions ... [more ▼]

Lacustrine sediments are particularly sensitive to modifications within the lake catchment. In a volcanic area, sedimentation rates are directly affected by the history of the volcano and its eruptions. Here, we investigate the impact of Mt. Fuji Volcano (Japan) on Lake Motosu and its watershed. The lacustrine infill is studied by combining seismic reflection profiles and sediment cores. We show evidence of changes in sedimentation patterns during the depositional history of Lake Motosu. The frequency of large mass-transport deposits recorded within the lake decreases over the Holocene. Before ~8000 cal yr BP, large sublacustrine landslides and turbidites were filling the lacustrine depression. After 8000 cal yr BP, only one large sublacustrine landslide was recorded. The change in sedimentation pattern coincides with a change in sediment accumulation rate. Over the last 8000 cal yr BP, the sediment accumulation rate was not sufficient enough to produce large sublacustrine slope failures. Consequently, the frequency of large masstransport deposits decreased and only turbidites resulting from surficial slope reworking occurred. These constitute the main sedimentary infill of the deep basin. We link the change in sediment accumulation rate with (i) climate and vegetation changes; and (ii) theMt. Fuji eruptions which affected the LakeMotosu watershed by reducing its size and strongly modified its topography. Moreover, this study highlights that the deposition of turbidites in the deep basin of Lake Motosu is mainly controlled by the paleobathymetry of the lakefloor. Two large mass-transport deposits, occurring around ~8000 cal yr BP and ~2000 cal yr BP respectively, modified the paleobathymetry of the lakefloor and therefore changed the turbidite depositional pattern of Lake Motosu. [less ▲]

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See detailSingle-grain feldspar luminescence chronology of historical extreme wave event deposits recorded in a coastal lowland, Pacific coast of central Japan
Riedesel, Svenja; Brill, Dominik; Roberts, Helen et al

in Quaternary Geochronology (2018), 45

The Shirasuka lowlands, located on the Enshu-nada coast of central Japan, record evidence for numerous ex- treme wave events. Here we test the applicability of using the luminescence signal from feldspars ... [more ▼]

The Shirasuka lowlands, located on the Enshu-nada coast of central Japan, record evidence for numerous ex- treme wave events. Here we test the applicability of using the luminescence signal from feldspars to date these young (< 1000 a) extreme wave event deposits. The signal used for dating is the IRSL signal (measured at 50 °C) as part of a post-IR IRSL130 procedure. We demonstrate that this IRSL50 (pre-IR130) signal results in reliable ages when corrected for fading, and the post-IR IRSL130 stimulation functions as an optical wash for both the natural/ regenerated luminescence signal (Lx) and the test dose signal (Tx), lowering the recuperation and removing any remaining charge from previous steps in the protocol. The single grain IRSL50 (pre-IR130) ages generated cover the historical record of the past 800 years and correlate well with past earthquakes and tsunamis in 1361 CE, 1498 CE and 1605 CE. Another identified tsunami deposit may correlate with the 1707 CE earthquake and tsunami. A slope failure deposit, probably caused by the earthquake in 1944 CE, is also identified. This study demonstrates that accurate ages can be determined for the young, extreme wave events at this site using the luminescence signal from feldspars. [less ▲]

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See detailMt. Fuji Holocene eruption history reconstructed from proximal lake sediments and high-density radiocarbon dating
Obrochta, Steve; Yokoyama, Yusuke; Yoshimoto, Mitsuhiro et al

in American Geophysical Union, Fall Meeting 2017 abstract (2017, December)

Understanding the eruption history of volcanos located near large population centers is of direct societal relevance. Here we present a 8,000-year lacustrine record that includes previously unreported ... [more ▼]

Understanding the eruption history of volcanos located near large population centers is of direct societal relevance. Here we present a 8,000-year lacustrine record that includes previously unreported eruptions of the active Mt. Fuji volcano, which receives approximately 47 million annual visitors with another 40 million living in the adjacent Kanto Plain. A high-fidelity age model is constructed from a number of terrestrial macrofossil and bulk organic radiocarbon measurements and is extremely consistent with the independently determined age of diagnostic tephra layers. In addition to reporting new eruptions, we also present more accurate ages for known eruptions and detect a wider distribution of ejecta for the most recent summit eruption, that latter of which will alter modeled prevailing wind vector during eruption. Furthermore, closely spaced fall-scoria layers, unlikely to be differentiated as separate events in land-based surveys, will lower the estimated mass of ejecta erupted and in turn reduce calculated magnitude. These results, the first of their kind from a highly populated region, demonstrate the utility of lacustrine sediments as powerful tools for understanding characteristics of volcanic eruptions and will improve disaster mitigation plans for the region. [less ▲]

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See detailKarstic phenomena of the BOUKADIR-Chlef. Geological, hydrogeological and mineralogical characterization
Moulana, Meriem Lina ULiege; Hubert, Aurelia ULiege; Guendouz, Mostefa

Conference (2017, November 17)

Calcareous environments occupy 10% of the surface of the globe (continents and seas),. The fragility, dissolution and rapid evolution of these formations constitute, in addition to the occurence of the ... [more ▼]

Calcareous environments occupy 10% of the surface of the globe (continents and seas),. The fragility, dissolution and rapid evolution of these formations constitute, in addition to the occurence of the karstic forms, a major risk and a potential hazard for the equilibrium of these grounds and more specifically for the infrastructures. Carbonate rocks are also present in the Mediterranean Basin and represents, depending on the country, about 30 to 70% of the surface area. The karstic formations also occur in Algeria. Among the best examples observed across the national territory are the ones found in: Tlemcen (karstification well developed at depth) and Saida (karstification well developed at the surface), the calcareous ridge of Djurdjura, Jijel... The region of Boukadir situated in the northern piedmont of Ouarsenis is the location of karstic forms and has witnessed the occurence a large collapse of the national road RN4 linking the wilaya of Algiers to Oran in 1988. However, this region has never been defined as a karstic region. For a better understanding of these phenomena, it’s essential to catalog and create an inventory of karstic forms developed in this region, to analyze in detail the geology and hydrogeology, using different tools such as : geological maps, drilling and different stratigraphic logs, aerial photography, hydrogeological and piezometric data, and of course, confirm all with a mineralogical study which is based on a morphoscopic analysis of thin sections and a diffractometric examination (DRX) of the samples collected around this locality. The Analysis and evaluation of this hazard is therefore dependent on the knowledge and study of the geology and hydrogeology of these lands, and especially the detection of the location of this phenomenon. [less ▲]

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See detailUsing lacustrine sediments to record past natural hazards: The case of Fuji Five Lakes (Japan)
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Yamamoto, Shinya et al

Scientific conference (2017, November 17)

In this presentation, we will focus on the Fuji Five Lakes region. Since 2013, Mt. Fuji and the Fuji Five Lakes area (Lake Motosu, Lake Shoji, Lake Sai, Lake Kawaguchi and Lake Yamanaka) are added on the ... [more ▼]

In this presentation, we will focus on the Fuji Five Lakes region. Since 2013, Mt. Fuji and the Fuji Five Lakes area (Lake Motosu, Lake Shoji, Lake Sai, Lake Kawaguchi and Lake Yamanaka) are added on the world heritage list of UNESCO. Mt. Fuji is a main touristic attraction in Japan bringing each year 300 000 tourists. The Fuji Five Lakes are located at the foot of Mt. Fuji Volcano close to the triple junction where the North American Plate, the Eurasian plate and the Philippine Sea Plate meet. Therefore, the region can be impacted by Mt. Fuji volcanic eruption as well as by large magnitude earthquakes. Additionally, nearly every year, Japan is hit by strong winds, heavy rains with flood, landslides and high waves. These natural hazards may affect the Japanese economy by causing casualties and infrastructure damage. In the regions frequently affected by natural disasters like Japan, it is crucial to have a better knowledge of the recurrence times of such disasters in order to refine the probabilistic models. For that purpose, lacustrine sediments are often used. Lacustrine sediments retrieving by coring offer several advantages compared to onland drilling: the method is cheaper, the cores are easier to take and they have longer temporal span. Lacustrine sediments are generally good archives to record past natural hazards. However, each lake has its own particular setting and a different sensitivity to record paleohazards. Coupling geophysical data, sedimentological analysis and historical records is often required to identify natural paleohazards in the sedimentary records and to define the threshold sensitivity of the lake. Here, we will used Fuji Five Lakes as natural laboratory for the recording of paleohazards (typhoons, earthquakes and volcanic eruptions) and will discuss the sedimentary record of Lake Motosu, Lake Sai, Lake Yamanaka and Lake Kawaguchi over the last ca. 6000 years regarding their geomorphological characteristics. [less ▲]

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See detailSedimentary infill at the western tip of the Gulf of Corinth during the last 120 ka: Evidence for an acceleration of the subsidence
Beckers, Arnaud; Hubert, Aurelia ULiege; Beck, Christian et al

Poster (2017, October 12)

The Corinth Rift, Greece, is a young and active continental rift stretching over 150 km between the cities of Patras and Athens, and is partly covered by the sea forming the Gulf of Corinth. The present ... [more ▼]

The Corinth Rift, Greece, is a young and active continental rift stretching over 150 km between the cities of Patras and Athens, and is partly covered by the sea forming the Gulf of Corinth. The present study is focused on the western tip of the Gulf, west of the town of Aigion, where the extension rate measured by GPS is the highest, reaching 14-16 mm/yr. The sediments were investigated using seismic reflection profiling (600 km) to characterize the evolution over the last 120 ka of the sedimentation, subsidence and faulting activity. We combined two lines of evidence, the position of lowstand deltas and isopach maps. The isopach maps were built using two stratigraphic markers could be traced through the seismic grid, the most recent one corresponds to the last post-glacial transgression and the antecedent one to MIS 6 / MIS 5 transgression, at ca. 130 ka. The related isopach maps evidence a spatial change in sedimentary infill along the rift axis probably related to a decrease in activity of the south-dipping faults (i.e. Trizonia/Mornos Faults) that formed the northern edge of the westernmost Corinth Rift in an early stage of the rifting. The different identified lowstand fluvio-deltaic deposits are related to global sea-level lowstands during which the Gulf of Corinth was a lake, whose last reconnection to the Sea occurred around 11.5 ka. Concerning lowstand deltas formed around 11.5 ka, the subsidence rates exceed 3 mm/yr and are maximal under the apex of the Mornos fan-delta (5.0-6.6 mm/yr) and in the hanging wall of the north-dipping Lambiri fault (5.9-7.5 mm/yr). Regarding the anterior lowstand delta, the subsidence was lower ranging from 1 to 2.7 mm/yr. These changes would arise because of the northward migration of the strain toward the north, e.g. the Marathias fault. [less ▲]

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See detailA 3000 yr paleoseismological history of the central East Anatolian Fault (Turkey) based on sedimentary record of Hazar Lake
Lamair, Laura ULiege; Hubert, Aurelia ULiege; Hage, Sophie et al

Poster (2017, October 10)

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. During the 20th century, the EAF activity was mostly quiestcent with only two events of magnitude greater than 6 recorded (1905 Malatya and the 1971 Bingol earthquakes). Historical seismicity suggests that the EAF is capable of generating earthquakes of magnitude greater than 7. In order to retrace the seismic history of the EAF in its central part, we study Hazar Lake. Hazar Lake is a 20 km long pull-apart basin with a maximum depth of 216 m. Short cores and long sediment cores were collected at four different sites to retrieve a paleoseismological record. Detailed analysis of the sediment cores (e.g. magnetic susceptibility, XRF, XRD, thin sections) were performed to identify sedimentary events. The ages of the sedimentary events were inferred based on a detailed age-depth model combining radiocarbon dating and 137Cs/210Pb. In total, 65 radiocarbon dating were done on bulk sediment and on terrestrial organic matter. The results show that Hazar Lake region was impacted by two fault zones: The East Anatolian Fault (EAF) and the North Anatolian Fault. Based on historical documents, the seismic intensity of each seismic event recorded in Hazar Lake was calculated. Here, we discuss the seismic threshold for earthquake records as well as the seismic recurrence pattern for the EAF over the last 3000 years. [less ▲]

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See detailLacustrine clay mineral assemblages as a proxy for land-use and climate changes over the last 4 kyr: The Amik Lake
El Ouahabi, Meriam ULiege; Hubert, Aurelia ULiege; Allan, Mohammed ULiege et al

Poster (2017, May 10)

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital ... [more ▼]

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital fraction, the lacustrine sediments record the history of soil erosion within its catchment via the inputs of clays and others detrital products. Within a Mediterranean context, the study investigates the upper sediments infilling the central part of the Amik basin in southern Turkey. This tectonic basin was occupied and exploited by modern human at least since 6000-7000 BC. We focus on the clay mineralogy (x-ray diffraction on oriented aggregates) and magnetic susceptibility measurements (Bartington) of the sedimentary record in the area over the last 4000 years, to assess environmental changes in relation with the different land uses and/or weathering during the successive Bronze, Iron, Roman, Islamic/Ottoman and Modern civilizations. The clay fraction of Amik Lake sediments comprises smectite, kaolinite, illite, chlorite and chlorite/smectite mixed layers that are the inherited clay phases. A relative change in abundance and crystallinity and chemistry of illite attests that environmental conditions evolved in the Amik Plain from the Bronze to Modern Age in relation with climates and/or land-use changes. The history of the Amik Lake reveals different soil erosion episode. The most intense erosion phase occurred during the Bronze/Iron Ages as indicated by the clay and magnetic susceptibility proxies. The Roman period was an exceptional period with soil erosion products arriving from the watershed, probably due the water channelization. A reduction of soil erosion occurred during the post Roman period until nowadays. Significant pedogenesis transformations are evidenced, especially during the Islamic/Ottoman periods suggesting intense chemical weathering conditions related to climate change. [less ▲]

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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 detailClay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)
El Ouahabi, Meriam ULiege; Hubert, Aurelia ULiege; Lamair, Laura ULiege et al

Poster (2017, April 23)

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing ... [more ▼]

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite particles are dispersed, and the suspension is stabilized supported by our SEM observations. In alkaline water, kaolinite reveals a lower degree of consolidation. While, alkaline water has no measurable effect on illite and chlorite surface properties due to the absence of modifications in charge. Illite and chlorite form with other clasts clusters or aggregate structures in suspension when the particle interactions are dominated by attractive energies were formed. The aggregate structure plays a major part in the flow behavior of clay suspensions. Flocs will immobilize the suspending medium, and give rise to increasing viscosity and yield strength of the suspension. [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 ▲]

Detailed reference viewed: 271 (2 ULiège)