Hydrological gravity response detection using a gPhone below- and aboveground

Toshiyuki, Tanaka; Miyajima, Rikio; Asai, Hidehiro; Horiuchi, Yasuharu; Kumada, Koji; Asai, Yasuhiro; Ishii, Hiroshi

doi:10.5047/eps.2012.06.012

Cited by 10 publications

(23 citation statements)

References 12 publications

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“…However, time-lapse surface gravity measurements alone provide poor information on the vertical water distribution. To remedy the absence of vertical resolution, gravity measurements can be done at different depths in caves or tunnels (Jacob et al, 2009;Tanaka et al, 2011). Time-lapse surface-to-depth (S2D) gravity measurements allow water storage variations in the unsaturated zone of the karst to be estimated.…”

Section: Introductionmentioning

confidence: 99%

Estimating epikarst water storage by time-lapse surface-to-depth gravity measurements

Champollion¹,

Deville²,

Chéry³

et al. 2018

Hydrol. Earth Syst. Sci.

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The magnitude of epikarstic water storage variation is evaluated in various karst settings using a relative spring gravimeter. Gravity measurements are performed over a 1.5-year period at the surface and inside caves at different depths on three karst hydro-systems in southern France: two limestone karst systems and one dolomite karst system. We find that significant water storage variations occur in the first 10 m of karst unsaturated zone. The subsurface water storage is also evidenced by complementary magnetic resonance sounding. The comparison between sites of the depth gravity measurements with respect to net water inflow suggests that seasonal water storage depends on the lithology. The transmissive function of the epikarst on the seasonal scale has been deduced from the water storage change estimation. Long (> 6 months) and short (< 6 months) transfer times are revealed in the dolomite and in the limestone respectively.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Introductionmentioning

confidence: 99%

Estimating epikarst water storage by time-lapse surface-to-depth gravity measurements

Champollion¹,

Deville²,

Chéry³

et al. 2018

Hydrol. Earth Syst. Sci.

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“…This has led to inconsistent approaches among studies so far. For reducing tides, Tanaka et al (), for instance, used the Baytap program (Tamura et al, ); other studies preferred ETERNA (Wenzel, ), for example, in Meurers et al (), or VAV program (Venedikov et al, ), for example, in Arnoso et al (). Much of the same variety can be found even in studies focusing on identical or similar phenomena, like local water storage changes, where for the correction of global atmospheric gravity effects; some studies (Hector et al, ) chose the École et Observatoire des Sciences de la Terre (EOST) atmospheric loading (Boy & Hinderer, ); and others (Creutzfeldt et al, ) preferred Atmacs (Klügel & Wziontek, ).…”

Section: Introductionmentioning

confidence: 99%

Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction‐Induced Uncertainty

2019

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Terrestrial gravimetry is increasingly used to monitor mass transport processes in geophysics boosted by the ongoing technological development of instruments. Resolving a particular phenomenon of interest, however, requires a set of gravity corrections of which the uncertainties have not been addressed up to now. In this study, we quantify the time domain uncertainty of tide, global atmospheric, large‐scale hydrological, and nontidal ocean loading corrections. The uncertainty is assessed by comparing the majority of available global models for a suite of sites worldwide. The average uncertainty expressed as root‐mean‐square error equals 5.1 nm/s2, discounting local hydrology or air pressure. The correction‐induced uncertainty of gravity changes over various time periods of interest ranges from 0.6 nm/s2 for hours up to a maximum of 6.7 nm/s2 for 6 months. The corrections are shown to be significant and should be applied for most geophysical applications of terrestrial gravimetry. From a statistical point of view, however, resolving subtle gravity effects in the order of few nanometers per square second is challenged by the uncertainty of the corrections.

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“…Superconducting gravimeters are generally used to make ground observations. Nevertheless, spring‐type gravimeters are also attractive (Kennedy & Ferré, ; Sofyan et al, ), especially for underground observation facilities; these devices reduce the installation problems that are associated with superconducting gravimeters (helium gas leakage and undesired sound), their mobility, and resistance against ground vibration (Jacob et al, ; Kennedy et al, ; Tanaka et al, ; Van Camp et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…In our earlier study, a spring‐type gPhone gravimeter that was manufactured by Micro‐g LaCoste, Inc., was used to detect rainfall responses on the order of 1 μGal under appropriate conditions (Tanaka et al, ). However, Tanaka et al () could not demonstrate whether rainfall responses could be separated from errors in the atmospheric reduction because a simple method, namely, the admittance factor (AF) method, was used to assess the responses. Performing such separations is especially difficult because most rainfall is accompanied by low‐pressure systems.…”

Section: Introductionmentioning

confidence: 99%

“…Most previous studies that have employed continuous gravity measurements were conducted using gravity stations with only one gravimeter. If multiple gravimeters that are located near each other are available, common causes of error (atmospheric and land‐water origins) can be canceled out or reduced (Kennedy et al, ; Tanaka et al, ). However, in other cases, the errors superimpose each other and could mask a signal.…”

Section: Introductionmentioning

confidence: 99%

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Vertical Gravimeter Array Observations and Their Performance in Groundwater‐Level Monitoring

Toshiyuki

Honda

2018

Earth and Space Science

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The gravitational effects of the atmosphere and subsurface water are significant obstacles to observing gravity variations on the sub‐μGal (1 μGal = 10 nm/s2) scale. The goal of this study is to detect changes in gravity that are caused by mass redistributions deep underground related to seismological phenomena by reducing environmental gravity effects using multiple gravimeters belowground and aboveground, which we term a “vertical gravimeter array.” Based on an evaluation of the responses to atmospheric effects and rainfall events identified in observations made with individual relative gravimeters, the vertical gravimeter array succeeds in stacking the target signals from deep underground and in reducing errors due to rainfall or free groundwater and atmospheric effects. To enable accurate interpretation, we introduce a physical approach that is based on attraction and loading deformation effects for atmospheric reduction using state‐of‐the‐art gridded weather data products. Changes in the water levels of confined groundwater can be regarded as a signal from deep underground, and a response coefficient of approximately −15 μGal/m was obtained. In addition, the response coefficient of the free groundwater level was determined to be approximately 5 μGal/m. Such array observations are expected to contribute to monitoring crustal activity and hydrological studies.

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Hydrological gravity response detection using a gPhone below- and aboveground

Cited by 10 publications

References 12 publications

Estimating epikarst water storage by time-lapse surface-to-depth gravity measurements

Estimating epikarst water storage by time-lapse surface-to-depth gravity measurements

Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction‐Induced Uncertainty

Vertical Gravimeter Array Observations and Their Performance in Groundwater‐Level Monitoring

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