1822 earthquake‐triggered homogenite in Lake Le Bourget (NW Alps)

Chapron, Emmanuel; Beck, Christian; Pourchet, M.; Deconinck, J.-F.

doi:10.1046/j.1365-3121.1999.00230.x

Cited by 176 publications

(190 citation statements)

References 36 publications

(35 reference statements)

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“…Kriging was chosen for interpolation between core locations. Additional constraints were included based on previous observations and on the literature; for example, cores taken above 50 m depth have never shown varves in Lake Bourget (Chapron et al 1999).…”

Section: Methodsmentioning

confidence: 99%

A spatiotemporal investigation of varved sediments highlights the dynamics of hypolimnetic hypoxia in a large hard‐water lake over the last 150 years

Jenny

Arnaud

Dorioz

et al. 2013

Limnology & Oceanography

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The spatiotemporal distribution of biochemical varves spanning the last 150 yr was investigated using 40 cores collected over a depth gradient in a large subalpine lake-Lake Bourget-in the French Alps. Four-dimensional sedimentological, biological, and geochemical analyses show that varve preservation can be used as a reliable proxy to reconstruct annual-to-decadal oscillations of hypoxia in large lakes. The volume of hypoxic waters was calculated by integrating the volume between the lake bottom and the depth of the shallowest varve-bearing core for each year. Although Lake Bourget bottom waters have been oxic over the last 9000 yr, severe hypoxia has occurred only since 1933 6 1. The volume of hypoxic waters showed, thereafter, a succession of pronounced fluctuations, leading to an increase of 8% of the total lake volume in the 1960s, a decline in the 1980s, and a second, ongoing increase since 1990. Whereas the initial onset of persistent hypoxic conditions could be attributed to eutrophication due to nutrient-rich inputs from sewage water and/or diffuse contamination, the later fluctuations were also driven by climatic factors, i.e., flooding, rising air temperatures, and phosphorus-independent changes in primary production. Hence, cumulative effects related to global warming seem to have driven hypolimnetic hypoxic conditions since equilibrium was initially disrupted due to a drastic shift in the trophic state.In both marine and freshwater ecosystems, hypoxia In many marine and freshwater ecosystems, humaninduced eutrophication, as a result of nutrient-mainly N and P-over-enrichment of waters, has caused bottomwater hypoxia (Carpenter 2005;Diaz and Rosenberg 2008). It seems logical, therefore, that nutrient abatement measures would result in a return to oxic conditions in bottom waters. However, recent research has shown that climatic changes can also trigger deoxygenation of deep habitats (Deutsch et al. 2011). Climate warming alters the water temperature and water-mass stability, which can affect bottom oxygen conditions by decreasing dioxygen In Lake Bourget, most symptoms of eutrophication (the increase in N : P ratio, the increase in water column transparency in spring, and the reduction in chlorophyll a concentrations) disappeared within the last 30 yr in response to a drastic drop in dissolved P content in water (Jacquet et al. 2005) following a restoration program that started in the 1980s. Counterintuitively, severe hypoxic conditions (defined here as the prolonged absence of bioavailable O 2 in the hypolimnion, leading to a drastic reduction of benthic fauna) still prevail in bottom waters, precluding a return to pre-industrial ecosystem conditions ). Our objective is to reconstruct the yearly intensity of hypolimnetic hypoxia over the last 150 yr in Lake Bourget and to qualitatively explore potential forcing factors related to nutrient concentration and climate.Because long-term monitoring data are scarce or missing and almost never cover the pre-industrial period, long-term

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Section: Methodsmentioning

confidence: 99%

A spatiotemporal investigation of varved sediments highlights the dynamics of hypolimnetic hypoxia in a large hard‐water lake over the last 150 years

Jenny

Arnaud

Dorioz

et al. 2013

Limnology & Oceanography

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“…Lauterbach et al, 2012) and (ii) on eight chronological markers: two AMS 14 C dates on macroremains, three AMS 14 C dates on bulk sediment corrected from the occurrence of fossil organic matter, two radiocarbon dates from the nearby archaeological site correlated with Ag/Sr peaks tracking former local mining activities, and the stratigraphic correlation of SE 11 with the slump deposit from core LBH03 dated by radionuclide and related to the impact of the AD1962 Corrençon earthquake located at 47 km from LBH . This age model ( figure 6D) allows estimating the chronology of SEs (table 2) and is comforted by the correlation of SE 10 with the AD1881 Allemond earthquake (Nomade et al, 2005;Guyard et al, 2007;Wilhelm et al, 2011) located at 6 km from LBH and SE 9 either with the largest regional earthquake located next to Lake Le Bourget at 80 km from LBH in AD1822 (the Chautagne event, Chapron et al, 1999;Guyard et al, 2007), or with a smaller but local event in AD1782 (the Uriage earthquake; Nomade et al, 2005;Wilhelm et al, 2011) located at 20 km from LBH ( figure 1B) . Similarly, SE 1 is, within the age-depth models errors, synchronous, with a major subaquatic slope failure event (the HDU) in Lake Le…”

Section: Lbh06 Age-depth Modelmentioning

confidence: 98%

Tracking Holocene glacial and high-altitude alpine environments fluctuations from minerogenic and organic markers in proglacial lake sediments (Lake Blanc Huez, Western French Alps)

Simonneau

Chapron

Garçon

et al. 2014

Quaternary Science Reviews

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“…The seismic profile shows that debris lobe 3 overlies and deforms the stratified lake sediments. These include debris overlain by a ponded, acoustically transparent interval representing an event bed as described from other lakes (Chapron et al, 1999;Schnellmann et al, 2006;Van Daele et al, 2015). The eastern part of the debris snout is crescentic-shaped with a steep edge (Fig.…”

Section: Southern Basin Plain With Major Debris Lobesmentioning

confidence: 93%

Morphological signatures of mass wasting and delta processes in a fjord-lake system: insights from Lovatnet, western Norway

Hansen¹,

Waldmann²,

Storms³

et al. 2016

NJG

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High-resolution bathymetrical data from the Lovatnet lake, western Norway, reveal a diverse morphology including traces from historic and prehistoric landslides. Onshore LiDAR and selected seismic profiles support the interpretation. Our data from the lake show significant debris lobes below Ramnefjellet that was the source of the well-known rock avalanche and tsunami disasters in 1905 and 1936 which caused a total of 134 casualties. The debris is divided into three main lobes reaching a total length of 1.8 km along the lake bottom from the impact site, and diffuse lobe features below the Bødalsdelta. Frontal deformations are minor. Lobes on the basin plain have a volume of more than 1.2 × 10 6 m 3 including debris entrained from the surrounding slopes and lake floor. The entire lake volume was set in motion during the catastrophic events. Returning bottom flows transported debris into the lake where lobes and minor, distinct mounds were deposited up to c. 1.5 km from the lake's outlet. The mounds could be anthropogenic, and possibly include a vessel that disappeared during the event. Erosion and smaller failures occurred elsewhere in the lake basin. Fan-delta morphologies are varied, with ridges and protuberances, reflecting deltaic sedimentation interrupted by major mass-wasting or other events in the deltas and/or their catchments. This is especially clear for the Raudi, Hellsete and Bødalen deltas, but minor protuberances are also found in other deltas. The data also reveal traces from large and previously undocumented landslide events. Gravitational deposits generally dominate the steep slopes and glacial landforms are scarce. The study demonstrates the importance of linking onshore and offshore morphological datasets in order to obtain an overview over process variability in fjord-type lakes of importance for further investigation and hazard assessment.

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1822 earthquake‐triggered homogenite in Lake Le Bourget (NW Alps)

Cited by 176 publications

References 36 publications

A spatiotemporal investigation of varved sediments highlights the dynamics of hypolimnetic hypoxia in a large hard‐water lake over the last 150 years

A spatiotemporal investigation of varved sediments highlights the dynamics of hypolimnetic hypoxia in a large hard‐water lake over the last 150 years

Tracking Holocene glacial and high-altitude alpine environments fluctuations from minerogenic and organic markers in proglacial lake sediments (Lake Blanc Huez, Western French Alps)

Morphological signatures of mass wasting and delta processes in a fjord-lake system: insights from Lovatnet, western Norway

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