Hydrogeological investigations at the Membach station, Belgium, and application to correct long periodic gravity variations

Camp, Michel Van; Vanclooster, Marnik; Crommen, O.; Petermans, T.; Verbeeck, K.; Meurers, Bruno; Dam, Tonie van; Dassargues, Alain

doi:10.1029/2006jb004405

Cited by 79 publications

(88 citation statements)

References 32 publications

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“…With the water distribution, θ(z, t), estimated as above, the changes in gravity associated with variations in the water distribution below the ground surface, g w (t), can be calculated by using the sum of the attraction effects (e.g., van Camp et al, 2006;Hasan et al, 2008):…”

Section: Methodsmentioning

confidence: 99%

“…However, gravity measurements are also sensitive to changes in land-water distributions in the vicinity of gravimeters. These changes originate from precipitation, snow cover, soil water infiltration, groundwater flow, river runoff and variations in the water level of oceans and lakes (e.g., Sato et al, 2001;Van Camp et al, 2006;Christiansen et al, 2011). To detect the minute gravity changes associated with solid-earth tectonics, water distribution effects in the original gravity data must be corrected to a high accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have carried out electrical resistivity surveys (Van Camp et al, 2006), lysimeter measurements (Creutzfeldt et al, 2010a), and borehole-core sampling (Creutzfeldt et al, 2010b), to understand, in detail, depthdependent water distributions below the ground surface; however, such depth profile data is not available for all gravity observation sites, mainly because of financial limitations. A different approach is to realize that the bulk of the water mass distribution occurs in the uppermost ground layers, because soil pores and free spaces at the ground surface can preserve significant amounts of water in the form of soil water and snow (e.g., Sato et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

et al. 2012

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Gravity changes associated with variations in local land-water distributions have been observed at Isawa Fan in northern Japan, and modeled by hydrological equations. We solve the Richards equation numerically for the time variation in the vertical soil moisture distribution, which is then spatially integrated to estimate gravity changes due to the soil moisture distribution. In modeling Isawa Fan, we assume a simple hydrological model: a horizontally homogeneous soil in an infinite half-space. The estimated gravity is consistent with the observed gravity during a 50-day period within about 0.4 µgal root mean square, owing to both observed soil parameter values and the observation building geometry being incorporated into the hydrological model. However, the estimated gravity cannot fully reproduce annual gravity changes observed during a 2-year time frame, because the boundary conditions in the modeling determine only local water distributions and the resultant short-period gravity changes. Instead, the observed gravity over these 2 years can be reproduced within about 1.0 µgal root mean square, if the additional parameters of the annual gravity change (A ac and A as ) and the snowfall effect (A s ) are calculated by the function regression to the observed gravity with the least-squares method. The hydrological modeling techniques presented here can be utilized at all gravity sites in flat areas similar to Isawa Fan, such that hydrological effects in gravity data can be corrected and mass transfers associated with earthquakes and volcanoes can be monitored.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

et al. 2012

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“…3). For the measurements, the step method (Torge, 1989) was applied. The points SG, AG, and MB were connected to a triangle; and each of the stations WE, DA, and ET was connected to two points of this triangle.…”

Section: Local Gravity Network and Observationsmentioning

confidence: 99%

“…Recent studies regarding the reduction of hydrological effects in gravity observations (Boy and Hinderer, 2006;Harnisch and Harnisch, 2006;Hokkanen et al, 2007a,b;Imanishi et al, 2006;Kroner and Jahr, 2006;Van Camp et al, 2006) emphasise that, in particular, local hydrological fluctuations have a major effect on geodynamic observations. The close vicinity of the station (< 100 m) may play a crucial role.…”

Section: Introductionmentioning

confidence: 99%

Detection of small hydrological variations in gravity by repeated observations with relative gravimeters

Naujoks

Weise

Kröner

et al. 2007

J Geod

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Abstract. Recently, a new application of timedependent gravity observations is emerging: the study of natural hydrological mass changes and their underlying processes. Complementary to GRACE data and continuous recordings with superconducting gravimeters, repeated observations with relative instruments on a local network may contribute to gain additional information on spatial changes in hydrology. The questions that need to be addressed are whether the results of these repeated measurements will be of sufficiently high resolution and accuracy, as well as how unique the information obtained will be. To examine this, a local gravity network with maximum point distances of 65 m was established in a hilly area around the Geodynamic Observatory Moxa, Germany. Using three to five LaCoste & Romberg relative gravimeters repeated measurements were carried out in a seasonal rhythm as well as at particular events like snowmelt or dryness in 17 campaigns between November 2004 and April 2007. The standard deviations obtained by least squares adjustment range from ±9 nm/s 2 to ±14 nm/s 2 for a gravity difference of one campaign, thus for gravity changes between two campaigns from ±13 nm/s 2 to ±20 nm/s 2 . Between the points of the network, spatial gravity changes of up to 171 nm/s 2 (139 nm/s 2 between two successive campaigns) could be proven significantly. They correlate with changes in the local hydrological situation. Particularly, a steep slope next to the observatory is identified as a gravimetrically significant hydrological compartment. The results obtained contribute to an improved reduction of the local hydrological signal in continuous gravity recordings and provide constraints to hydrological models.

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Absolute gravity change associated with magma mass movement in the conduit of Asama Volcano (Central Japan), revealed by physical modeling of hydrological gravity disturbances

et al. 2015

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The gravity signal originating from magma mass movement in a volcanic conduit is retrieved from the hydrologically disturbed absolute gravity data obtained at Asama Volcano (Central Japan) in 2004, using a three‐dimensional hydrological model. We improve the hydrological model of the previous study using realistic soil parameters and boundary conditions, to better estimate the spatiotemporal land‐water distributions and the consequent hydrological gravity disturbances. The newly estimated gravity disturbances agree with the absolute gravity values observed by FG5 gravimeters in 2004–2009 within about 2.6 μGal, by additionally accounting for the excess discharge of groundwater mass associated with a sloping impermeable surface below the discharge area. After the gravity disturbance of 20 μGal amplitude is subtracted from the absolute gravity data observed during the 2004 eruptive event, the gravity residual of 5 μGal amplitude shows a significant decrease in synchronization with eruptions, because the ascending magma mass in the conduit affects the upward attraction force to the gravimeters installed on the flank of Asama Volcano. The magma head altitude, to which the residual gravity is converted assuming a homogeneous linear density in the conduit, shows a comprehensive agreement of the time variation in the magma head with those in other volcanic observations, such as gas emission rate and earthquake frequency. By correcting the hydrological gravity disturbances using this hydrological model and simultaneously obtained meteorological data in real time, spatiotemporal variations in the magma mass can be instantaneously monitored at Asama Volcano, even before eruptions during future volcanic events.

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Hydrogeological investigations at the Membach station, Belgium, and application to correct long periodic gravity variations

Cited by 79 publications

References 32 publications

Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

Detection of small hydrological variations in gravity by repeated observations with relative gravimeters

Absolute gravity change associated with magma mass movement in the conduit of Asama Volcano (Central Japan), revealed by physical modeling of hydrological gravity disturbances

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