Search publications of the members of the Royal Belgian institute of natural Sciences
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Surface movement above old coal longwalls after mine closure
- Although most subsidence occurs in the months and years after mining by the longwall method, surface movement is still occurring many decades after the mining. The aim of the study is to quantify the long term behavior. Satellite data (radar-interferometry) were analyzed to study an area of about 2km2 during the 18years following the closure of the underground infrastructure and the flooding of the underground workings and rock mass. It was observed that, on average, a residual downward movement took place till 7–12years after the closure, followed by a clear uplift. However, the first signs of an uplift occurred in certain sub-areas 3–4years after the closure. Zones within the area studied were identified with either larger or smaller movements. However, the spatial variation of the surface subsidence or uplift could not be directly explained by the characteristics of mining.
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Subsidence related to groundwater pumping for breweries in Merchtem area (Belgium), highlighted by Persistent Scaterrer Interferometry
- ERS, ENVISAT and TerraSAR-X Synthetic Aperture Radar scenes covering the time span 1992–2014 were processed using a Persistent Scatterer technique to study the ground movements in Merchtem (25km NW of Brussels, Belgium). The processed datasets, covering three consecutive time intervals, reveal that the investigated area is affected by a global subsidence trend related to the extraction of groundwater in the deeper Cambro-Silurian aquifer. Through time the subsidence pattern is reduced and replaced by an uplift related to the rising water table attested by piezometers located in this aquifer. The subsidence is finally reduced to a zone where currently three breweries are very active and pump groundwater in the Ledo-Paniselian aquifer and in the Cambro-Silurian for process water for the production.
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Understanding and predicting the impact of the interaction between oceanographic and biological factors on larval recruitment and population connectivity in flatfish
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L’eutrophisation : manifestations, causes, conséquences et prédictibilité. Synthèse de l’Expertise scientifique collective CNRS – IFREMER – INRA – Irstea (France), 148 pages.
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Significant loss of mitochondrial diversity within the last century due to extinction of peripheral populations in eastern gorillas
- Species and populations are disappearing at an alarming rate as a direct result of human activities. Loss of genetic diversity associated with population decline directly impacts species’ long-term survival. Therefore, preserving genetic diversity is of considerable conservation importance. However, to assist in conservation efforts, it is important to understand how genetic diversity is spatially distributed and how it changes due to anthropogenic pressures. In this study, we use historical museum and modern faecal samples of two critically endangered eastern gorilla taxa, Grauer’s (Gorilla beringei graueri) and mountain gorillas (Gorilla beringei beringei), to directly infer temporal changes in genetic diversity within the last century. Using over 100 complete mitochondrial genomes, we observe a significant decline in haplotype and nucleotide diversity in Grauer’s gorillas. By including historical samples from now extinct populations we show that this decline can be attributed to the loss of peripheral populations rather than a decrease in genetic diversity within the core range of the species. By directly quantifying genetic changes in the recent past, our study shows that human activities have severely impacted eastern gorilla genetic diversity within only four to five generations. This rapid loss calls for dedicated conservation actions, which should include preservation of the remaining peripheral populations.
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Reply to “Comment on “Ecological niche of Neanderthals from Spy Cave revealed by nitrogen isotopes of individual amino acids in collagen.” [J. Hum. Evol. 93 (2016) 82–90]” [J. Hum. Evol. 117 (2018) 53–55]
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Additional data on eastern Pantepui Orthalicoidea land snails (Mollusca, Gastropoda)
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Screening of suitability of pelitic rocks in Belgium for radio-active waste disposal
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Screening of suitability of pelitic rocks in Belgium for radio-active waste disposal
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Middeleeuwse aanlegplaats “Bierwerf” aan de Scheldekaaien in Antwerpen. Natuursteenbeschrijving en -interpretatie. Studie in opdracht van: Stad Antwerpen, Dienst Stadsontwikkeling.
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Natuursteenonderzoek Sint-Amanduskerk Denderleeuw. In opdracht van : INTERGEMEENTELIJKE SAMENWERKING VOOR STREEKONTWIKKELING IN ZUID OOST-VLAANDEREN
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Een licht gekleurd alternatief voor blauwe steen: Comblanchien.
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Archeologische opgraving Noorderterras. Natuursteen in de depositie van ballaststeen en hergebruikte bouwmaterialen van de Burcht, Scheldekaaien – Noorderterras (Antwerpen): aanvullend onderzoek van gesteenten opgeslagen in het Felixarchief.
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Geodiversity of a stone deposit in the old city centre of Antwerp. Source of information on roman and medieval trade and use. 8th International Geologica Belgica Meeting 2024, 11-13 September 2024, Liège.
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Airborne monitoring of compliance to NOx emission regulations from ocean-going vessels in the Belgian North Sea
- Along the worldwide tightening of standards for sulphur emission from ocean going vessels (OGVs) come actions that are also being taken to reduce nitrogen emission. Particularly, as a milestone in this regard, on January 1st, 2021 the NOx Emission Control Area (NECA) for the North Sea and Baltic Sea came into effect. In response to the newly established NECA, the sniffer sensor system on the Belgian coastguard aircraft was modified and extended with a NOx sensor. Moreover, a methodology was developed to evaluate OGV compliance to the NOx emission limits through in situ measurements of the plume exhaust. The quality and uncertainty of the measurements demonstrate that it is likely to achieve an effective compliance monitoring of the NOx emission standards on the sea. Those emission standards are further divided into four tiers depending on the keel laying date. As has been proved by the results, NOx emissions for Tier II OGVs, contrary to what might be expected, are on average higher than those for Tier I OGVs. What is even more problematic, Tier II OGVs have also more often been found to be non-compliant than Tier I OGVs.
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VanNoten_Bruniquel
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Electric and passive seismic geophysical survey in a protected cave environment: the Bruniquel cave (France)
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Bedrock morphology modelling using geologically-dependent empirical equations between resonance frequency and bedrock depth
- Calculating thickness variations of soft sediments above bedrock is important for site effect characterisation, earthquake ground motion amplification and for hydrogeological and geothermal purposes. In case seismic array instrumentation is not available and hence shear-wave velocity profiles cannot be obtained, other correlation techniques need to be applied to accurately deduce bedrock depth. Nakamura’s H/V Spectral Ratio (HVSR) analysis of ambient noise is a powerful seismological method to reveal a site’s resonance frequency. The conversion from a resonance map to a bedrock depth map in areas with a different sedimentary cover in terms of layer thickness and lithologies is, however, not straightforward. Converting resonance frequencies to depth by applying a mean shear-wave velocity (Vs) will under- and overestimate bedrock depth at higher and lower topographies, respectively. Applying an empirical log-log (powerlaw) relationship between resonance frequency (obtained from HVSR analyses) and bedrock depth (obtained from boreholes) provides a much better depth estimation that considers the non-linear increase of Vs with depth. Accurate empirical equations can however only be constructed from HVSR measurements performed in areas with similar lithological sediments. In this study we present a high-resolution microzonation study performed in Brussels (Belgium) where both the sedimentary cover and the fractured top of the bedrock (i.e. the Brabant Massif) are of interest for their geothermal potential. Using 88 ambient noise measurements above boreholes we constructed four different powerlaw equations that are applicable to convert resonance frequency to depth in areas with a clayey, sandy-clayey, alluvial-clayey and alluvial sedimentary cover. Subsequently, 405 ambient noise measurements were conducted and converted to virtual boreholes using these four empirical equations. Measurements were used to map out bedrock depth in a 15km2 and a 25 km2 area applying a 200 m and 500 m station density spacing, respectively. The results demonstrate the presence of NW-SE oriented, 20 m-high ridges at 100 m depth that stand out because of differential erosion between less-resistant slaty (Tubize Formation) and hard quartzitic (Blanmont Formation) rock formations of the Brabant Massif. Separating seismic data according to their subsurface geology results in more accurate empirical frequency-depth conversion equations than if only one equation would be used for an entire area.
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Integration of corrective parameters to merge multiple-sourced online macroseismic data
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Investigations géophysiques du plancher calcite et du remplissage sédimentaire de la Salle de la structure de Bruniquel
