On: “Gravity vertical gradient measurements for the detection of small geologic and anthropogenic forms” by Z. J. Fajklewicz (GEOPHYSICS, October 1976, p. 1016–1030)

Geophysics ◽  
1977 ◽  
Vol 42 (4) ◽  
pp. 872-873
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Research Work ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Wind Gust ◽  
Near Surface ◽  
New Methods ◽  
Vertical Gravity Gradient ◽  
Surface Variation ◽  
Gradient Measurements ◽  
Vertical Gravity

In his paper, Fajklewicz discusses the improvement of vertical gravity gradient measurements arising from a very stable tower apparently not affected by wind gust vibration and climatic changes. Further, the lower plate where the gravity meter is resting can be changed in position to avoid possible disturbances from surface and near‐surface variation, and new methods for correcting and interpreting observed gradients over the vertical interval of about 3 m are presented. Some 1000 field stations were observed, including research work and industrial application.

VERTICAL GRADIENT OF GRAVITY ON AXIS FOR HOLLOW AND SOLID CYLINDERS

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 816-820 ◽  
Author(s):  
Thomas A. Elkins
Keyword(s):  
Hollow Cylinder ◽  
Sudden Change ◽  
Vertical Gradient ◽  
Outer Radius ◽  
Gravity Gradient ◽  
Gradient Effect ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity ◽  
Special Case ◽  
Vertical Gradient Of Gravity

The recent interest in borehole gravimeters and vertical gravity gradient meters makes it worthwhile to analyze the simple case of the vertical gravity gradient on the axis of a hollow cylinder, simulating a borehole. From the viewpoint of potential theory the results are interesting because of the discontinuities which may occur when a vertical gradient profile crosses a sudden change in density. Formulas for the vertical gradient effect are given for observations above, inside, and below a hollow cylinder and a solid cylinder. The special case of an infinitely large outer radius for the cylinders is also considered, leading to formulas for the vertical gradient effect inside a borehole on its axis and inside a horizontal slab. Some remarks are made on the influence of the shape of a buried vertical gradient meter on the correction factor for changing the meter reading to density.

POSSIBLE APPLICATION OF THE ANOMALOUS FREE‐AIR VERTICAL GRADIENT TO MARINE EXPLORATION

Geophysics ◽  
1966 ◽  
Vol 31 (1) ◽  
pp. 260-263
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Vertical Cylinder ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Average Gradient ◽  
Vertical Gravity Gradient ◽  
Free Air ◽  
Vertical Gravity ◽  
Lithologic Unit ◽  
Marine Exploration ◽  
Anomalous Average

Recently it could be shown (Thyssen‐Bornemisza, 1965) that a vertical lithologic unit cylinder generates a relatively strong anomalous free‐air vertical gravity gradient F′ along the cylinder axis. The following simple example may serve as a demonstration. A small vertical cylinder made of gold or tungsten, where radius r and length L are identical, would generate the anomalous average gradient F′∼3,223 Eötvös units over the interval h=r=L going from the cylinders top surface upward. Suppose r=l=1 cm, then an average gradient exceeding the earth’s normal free‐air vertical gradient F is present over the interval h=1 cm.

Depth estimates from ratios of gravity, geoid, and gravity gradient anomalies

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 123-136 ◽  
Author(s):  
Carl Bowin ◽  
Edward Scheer ◽  
Woollcott Smith
Keyword(s):  
Frequency Domain ◽  
Spectral Methods ◽  
Depth Estimation ◽  
Data Type ◽  
Gravity Gradient ◽  
Data Types ◽  
Vertical Gravity Gradient ◽  
Frequency Domain Methods ◽  
Gradient Measurements ◽  
Vertical Gravity

The utility of combining geoid, gravity, and vertical gravity gradient measurements for delineation of causative mass anomalies is explained and compared with spatial and spectral methods for depth estimation. Depth rules for various source geometries are reviewed and new rules developed for geoid, gravity, and vertical gravity‐gradient data. Both spatial and frequency‐domain methods are discussed. Simple ratios of single observations of different data types (e.g., geoid, gravity, or vertical gravity gradient) are shown to provide information comparable to the traditional spatial and frequency analyses of one data type alone.

Detection of subsurface water storage dynamics with combined gravity - vertical gravity gradient monitoring and hydrological simulation

2020 ◽  
Author(s):  
Anne-Karin Cooke ◽  
Cédric Champollion ◽  
Pierre Vermeulen ◽  
Camille Janvier ◽  
Bruno Desruelle ◽  
...  
Keyword(s):  
Water Content ◽  
Water Storage ◽  
Subsurface Water ◽  
Precipitation Event ◽  
Gravity Gradient ◽  
Small Scale ◽  
Heterogeneous Distribution ◽  
Near Surface ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity

<p>Time-lapse ground-based gravimetry is increasingly applied in subsurface hydrology, providing mass balance constraints on water storage dynamics. For a given water content change as e.g. after a precipitation event, the simplest assumption is that of a homogeneous, infinite slab (Bouguer plate) of water column causing the measurable increase in gravitational attraction. For heterogeneous subsurface environments such as karst aquifers at field scale this assumption may not always hold. The gravity signal is depth-integrated and non-unique, hence indistinguishable from a heterogeneous distribution without further information.</p><p>Exploiting the different spatial sensitivities of gravity and vertical gravity gradient (VGG) data can shed light on the following questions:</p><p> </p><ul><li> <p>Is the subsurface water content within the gravimeter’s footprint likely to be homogeneous or showing small-scale heterogeneity?</p> </li> <li> <p>If not, at which distance are these mass heterogeneities and how large are they?</p> </li> <li> <p>Which monitoring set-ups (tripod heights, number of and distance between VGG measurement locations) are likely to detect mass heterogeneity of which spatial characteristics?</p> </li> </ul><p>One year of monthly vertical gravity gradient surveys has been completed in the geodetic observatory in karstic environment on the Larzac plateau in southern France. We interpret the VGG observations obtained in this field study in the context of further available hydraulic and geophysical data and hydro-gravimetrical simulation. Finally, practical applications in view of detecting near-surface voids and reservoirs of different porosities as well as their storage capacity and seasonal dynamics are evaluated.</p>

scholarly journals The use of microgravity technique in archaeology: A case study from the St. Nicolas Church in Pukanec, Slovakia

2009 ◽  
Vol 39 (3) ◽  
pp. 237-254 ◽  
Author(s):  
Jaroslava Pánisová ◽  
Roman Pašteka
Keyword(s):  
Local Density ◽  
Measurement Techniques ◽  
Bouguer Anomaly ◽  
Roman Catholic Church ◽  
Gravity Measurement ◽  
Gravity Gradient ◽  
Near Surface ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity

The use of microgravity technique in archaeology: A case study from the St. Nicolas Church in Pukanec, SlovakiaThe detection of subsurface cavities, such as crypts, cellars and tunnels, in churches and castles belongs to successful applications of the employment of surface gravity measurement techniques in archaeo-prospecting. The old historic building exploration requires using of non-invasive methods, and hence the microgravity technique is a proper candidate for this task. On a case study from the Roman-Catholic Church of St. Nicolas in the town Pukanec the results of using microgravity for detection and delineation of local density variations caused by a near-surface void are shown. The acquired negative anomaly in the residual Bouguer anomalies field suggested the presence of a possible void feature. Euler deconvolution and 3D modelling were used to estimate the depth and shape of the anomalous source. Additionally, measurements of the vertical gravity gradient on several stations were performed. We tested how the use of a downward continuation of gravity, utilizing the real vertical gravity gradient, influences the shape and amplitude of the final Bouguer anomaly map.

On: “Variations of Vertical Gravity Gradient in New York City and Alpine, New Jersey” by John T. Kuo, Mario Ottaviani, and Shri K. Singh (GEOPHYSICS, April 1969, p. 235–248).

Geophysics ◽  
1970 ◽  
Vol 35 (3) ◽  
pp. 521-522 ◽  
Author(s):  
Stephen Thyssen-Bornemisza
Keyword(s):  
New York ◽  
New York City ◽  
New Jersey ◽  
York City ◽  
Vertical Gradient ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity

In their paper, Kuo et al, following the footsteps of Hammer (1938), reported interesting vertical gradient observations in high buildings with a gravity meter. However, conclusion (5) drawn by Kuo et al should be discussed briefly in order to avoid an incorrect impression.

scholarly journals Analysis of Groundwater Decline and Land Subsidence by using of Microgravity and Vertical Gravity Gradient Over Time Method

2014 ◽  
Vol 15 (1) ◽  
pp. 7 ◽  
Author(s):  
Suhayat Minardi ◽  
Hiden Hiden ◽  
Daharta Dahrin ◽  
Mahmud Yusuf
Keyword(s):  
Gravity Anomaly ◽  
Land Subsidence ◽  
Gravity Data ◽  
Vertical Gradient ◽  
Time Lapse ◽  
Gravity Gradient ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity ◽  
Groundwater Decline ◽  
Over Time

Studies have been conducted to identify the occurrence of subsidence, a decline of groundwater, and to model the causes of subsidence in areas of Jakarta based on response of microgravity anomaly and vertical gravity gradient over time. Based on the processing and interpretation of gravity data advance of the time concluded that by using a combination of time lapse microgravity and its vertical gradient have been able to localize the source of the gravity anomaly and the results are strongly support the results of filtering to separate the source of the anomaly. The subsidence that occurs predominantly due to resettlement (in West and North Jakarta), caused by the extraction of groundwater and resettlement (in Central and East Jakarta), and dominated due to the extraction of groundwater (in South Jakarta).Keywords : Groundwater, time lapse micogravity, time lapse vertical gradient, resettlement, subsidence

OBSERVATION OF THE VERTICAL GRADIENT OF GRAVITY IN THE FIELD

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 771-779 ◽  
Author(s):  
Stephen Thyssen‐Bornemisza ◽  
W. F. Stackler
Keyword(s):  
Vertical Gradient ◽  
Gravity Gradient ◽  
Field Observations ◽  
Vertical Gravity Gradient ◽  
Vertical Gravity ◽  
Vertical Gradient Of Gravity

Field observations of the anomalous vertical gravity gradient were made at Houston, Texas, and over the Turner Valley structure near Calgary, Alberta, Canada. The results obtained are encouraging, but the precision of the measurements was to some extent reduced by vibrations generated in transporting the gravimeter up and down the tripod, as well as by gusts of wind.

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