References of "Van Camp, Michel"
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See detailRecording Belgium's Gravitational History
Van Camp, Michel; Francis, Olivier UL; Lecocq, Thomas

in EOS : Transactions, American Geophysical Union (2017)

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See detailThe gravity of geophysics
Van Camp, Michel; de Viron, Olivier; Watlet, Arnaud et al

in EOS : Transactions, American Geophysical Union (2017), 98

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See detailGeophysics From Terrestrial Time-Variable Gravity Measurements
Van Camp, Michel; de Viron, Olivier; Watlet, Arnaud et al

in Reviews of Geophysics (2017), 55

In a context of global change and increasing anthropic pressure on the environment, monitoring the Earth system and its evolution has become one of the key missions of geosciences. Geodesy is the ... [more ▼]

In a context of global change and increasing anthropic pressure on the environment, monitoring the Earth system and its evolution has become one of the key missions of geosciences. Geodesy is the geoscience that measures the geometric shape of the Earth, its orientation in space, and gravity field. Time-variable gravity, because of its high accuracy, can be used to build an enhanced picture and understanding of the changing Earth. Ground-based gravimetry can determine the change in gravity related to the Earth rotation fluctuation, to celestial body and Earth attractions, to the mass in the direct vicinity of the instruments, and to vertical displacement of the instrument itself on the ground. In this paper, we review the geophysical questions that can be addressed by ground gravimeters used to monitor time-variable gravity. This is done in relation to the instrumental characteristics, noise sources, and good practices. We also discuss the next challenges to be met by ground gravimetry, the place that terrestrial gravimetry should hold in the Earth observation system, and perspectives and recommendations about the future of ground gravity instrumentation. [less ▲]

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See detailMultiscale hydrogeological and hydrogeophysical approach to monitor vadose zone hydrodynamics of a karst system
Watlet, Arnaud; Poulain, Amaël; Francis, Olivier UL et al

Poster (2016)

The vadose zone of karst systems plays an important role on the water dynamics. In particular, temporary perched aquifers can appear in the subsurface due to changes of weather conditions, reduced ... [more ▼]

The vadose zone of karst systems plays an important role on the water dynamics. In particular, temporary perched aquifers can appear in the subsurface due to changes of weather conditions, reduced evapotranspiration and the vertical gradients of porosity and permeability. Although many difficulties are usually encountered when studying karst environments due to their heterogeneities, cave systems offer an outstanding opportunity to investigate vadose zone from the inside. We present a multi-scale study covering two years of hydrogeological and geophysical monitoring of the Lomme Karst System (LKS) located in the Variscan fold-and-thrust belt (Belgium), a region (∼3000 ha) that shows many karstic networks within Devonian limestone units. Hydrogeological data cover the whole LKS and involve e.g. flows and levels monitoring or tracer tests performed in both vadose and saturated zones. Such data bring valuable information on the hydrological context of the studied area at the catchment scale. Combining those results with geophysical measurements allows validating and imaging them at a smaller scale, with more integrative techniques. Hydrogeophysical measurements are focused on only one cave system of the LKS, at the Rochefort site (∼40 ha), taking benefit of the Rochefort Cave Laboratory (RCL) infrastructures. In this study, a microgravimetric monitoring and an Electrical Resistivity Tomography (ERT) monitoring are involved. The microgravimetric monitoring consists in a superconducting gravimeter continuously measuring gravity changes at the surface of the RCL and an additional relative gravimeter installed in the underlying cave located 35 meters below the surface. While gravimeters are sensible to changes that occur in both the vadose zone and the saturated zone of the whole cave system, combining their recorded signals allows enhancing vadose zone’s gravity changes. Finally, the surface ERT monitoring provide valuable information at the (sub)-meter scale on the hydrological processes that occur in the vadose zone. Seasonal water variations and preferential flow path are observed. This helps separating the hydrological signature of the vadose zone from that of the saturated zone. [less ▲]

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See detailTemporal variation of tidal parameters in superconducting gravimeter time-series
Meurers, Bruno; Van Camp, Michel; Francis, Olivier UL et al

in Geophysical Journal International (2016), 205(1), 284-300

Analysing independent 1-yr data sets of 10 European superconducting gravimeters (SG) reveals statistically significant temporal variations of M2 tidal parameters. Both common short-term (<2 yr) and long ... [more ▼]

Analysing independent 1-yr data sets of 10 European superconducting gravimeters (SG) reveals statistically significant temporal variations of M2 tidal parameters. Both common short-term (<2 yr) and long-term (>2 yr) features are identified in all SG time-series but one. The averaged variations of the amplitude factor are about 0.2‰. The path of load vector variations equivalent to the temporal changes of tidal parameters suggests the presence of an 8.85 yr modulation (lunar perigee). The tidal waves having the potential to modulate M2 with this period belong to the 3rd degree constituents. Their amplitude factors turn out to be much closer to body tide model predictions than that of the main 2nd degree M2, which indicates ocean loading for 3rd degree waves to be less prominent than for 2nd degree waves within the M2 group. These two different responses to the loading suggest that the observed modulation is more due to insufficient frequency resolution of limited time-series rather than to time variable loading. Presently, SG gravity time-series are still too short to prove if time variable loading processes are involved too as in case of the annual M2 modulation known to appear for analysis intervals of less than 1 yr. Whatever the variations are caused by, they provide the upper accuracy limit for earth model validation and permit estimating the temporal stability of SG scale factors and assessing the quality of gravity time-series. [less ▲]

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See detailThe quest for a consistent signal in ground and GRACE gravity time series
Van Camp, Michel; de Viron, Olivier; Métivier, Laurent et al

in Geophysical Journal International (2014), 197

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See detailReply to Comment on: ‘The quest for a consistent signal in ground and GRACE gravity time series’
Van Camp, Michel; de Viron, Olivier; Métivier, Laurent et al

in Geophysical Journal International (2014), 199(3), 1818-1822

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See detailComparison between the Transfer Functions of three Superconducting Gravimeters
Francis, Olivier UL; Lampitelli, Carmine UL; Klein, Gilbert UL et al

in Marées Terrestres Bulletin d'Informations (2011), 147

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See detailRevisiting absolute gravimeter intercomparisons
de Viron, O.; Van Camp, Michel; Francis, Olivier UL

in Metrologia (2011), 48

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See detailFinal report on the Seventh International Comparison of Absolute Gravimeters (ICAG 2005)
Jiang, Z.; Francis, Olivier UL; Vitushkin, L. et al

in Metrologia (2011), 48

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See detailFinal report on absolute gravimeter intercomparison (EURAMET Project no. 1093)
Baumann, Henri; Francis, Olivier UL; Van Camp, Michel

in Metrologia (2010), 47(1A), 07008

An interlaboratory comparison (Euramet Project 1039) of three absolute gravimeters was carried out between the national metrology institutes of Luxembourg, Belgium and Switzerland (University of ... [more ▼]

An interlaboratory comparison (Euramet Project 1039) of three absolute gravimeters was carried out between the national metrology institutes of Luxembourg, Belgium and Switzerland (University of Luxembourg/ECGS, Royal Observatory of Belgium and Federal Office for Metrology METAS). The comparison was hosted in the Underground Laboratory for Geodynamics in Walferdange. The obtained results confirm a perfect agreement between the instruments used with respective expanded uncertainties ( k = 2) of 4.25 µGal. Finally, a link to the Euramet project 1030 shows that the three gravimeters are coherent with the 19 other gravimeters. Main text. To reach the main text of this paper, click on Final Report [http://www.bipm.org/utils/common/pdf/final_reports/M/G-S1/EURAMET.M.G-S1.pdf] . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ [http://kcdb.bipm.org/] . The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA). [less ▲]

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See detailIs the instrumental drift of superconducting gravimeters a linear or exponential function of time?
Van Camp, Michel; Francis, Olivier UL

in Journal of Geodesy (2007), 81(5), 337-344

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See detailUncertainty of absolute gravity measurements
Van Camp, Michel; Williams, Simon D. P.; Francis, Olivier UL

in Journal of Geophysical Research (2005), 110(B05406), 1-9

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See detailIndication of the uplift of the Ardenne in long-term gravity variations in Membach (Belgium)
Francis, Olivier UL; Van Camp, Michel; van Dam, Tonie UL et al

in Geophysical Journal International (2004), 158(1), 346-352

We report on the results of 7 yr of collocated gravity observations made with an FG5 abso- lute (AG) gravimeter and a GWR C-Series superconducting gravimeter (SG) located at the Membach Geophysical ... [more ▼]

We report on the results of 7 yr of collocated gravity observations made with an FG5 abso- lute (AG) gravimeter and a GWR C-Series superconducting gravimeter (SG) located at the Membach Geophysical Station in eastern Belgium. The SG gravity residuals track changes in gravity periodically observed by the AG, at the microgal level. Further, in the SG resid- ual signal we distinguish a quasi-seasonal term that can be mostly explained by variations in local water storage effects. In the AG time-series we observe a small trend in the gravity of −0.6 ± 0.1 μGal yr−1 perhaps indicating that the Membach Station is being displaced up- wards by about 3.0 mm yr−1. An uplift of the region is confirmed by Global Positioning System (GPS) measurements performed 3 km away. We are able to explain the features in the gravity time-series in terms of water storage variability, post-glacial rebound and tectonic activity. [less ▲]

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See detailComment on "Nature of the recent vertical ground movements inferred from high-precision leveling data in an intraplate setting: NE Ardenne, Belgium" by A. Demoulin and A. Collignon
Camelbeeck, Thierry; Van Camp, Michel; Jongmans, Denis et al

in Journal of Geophysical Research (2002), 107(B11), 2281-2281

Comment on ‘‘Nature of the recent vertical ground movements inferred from high-precision leveling data in an intraplate setting: NE Ardenne, Belgium’’ by A. Demoulin and A. Collignon

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See detailAbsolute gravity measurements in Belgium: a tool for geodynamic interpretation
Van Camp, Michel; Francis, Olivier UL; Camelbeeck, Thierry

in Degryse, Patrick; Sintubin, Manuel (Eds.) Contributions to the Geology of Belgium and Northwest Europe (2002)

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See detailAccurate transfer function determination for superconducting gravimeters
Van Camp, Michel; Wenzel, H.-G.; Schott, P. et al

in Geophysical Research Letters (2000), 27(1), 37-40

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