Gsolve, a Python computer program with a graphical user interface to transform relative gravity survey measurements to absolute gravity values and gravity anomalies

McCubbine, Jack; Tontini, F. Caratori; Stagpoole, Vaughan; Smith, Euan; O'Brien, Grant

doi:10.1016/j.softx.2018.04.003

Cited by 15 publications

(18 citation statements)

References 4 publications

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“…Relative gravity meters are calibrated at the time of manufacture, but it is desirable to regularly check their accuracy as they age (Reilly 1970;Sasagawa et al 1989;Carbone and Rymer 1999;Onizawa 2019). This is usually achieved by making multiple observations between sites with a precisely known gravity difference to determine a calibration scale factor (β) for the meter (Reilly 1970;McCubbine et al 2018;Fukuda et al 2019;Supplementary File 4). In New Zealand several calibration ranges have been established in the Wellington region, Taupō and Christchurch.…”

Section: Gravity Meter Calibration Rangesmentioning

confidence: 99%

“…These observations are the basis for a project to re-evaluate the gravity reference stations throughout New Zealand, with the whole network, including harbour stations, now tied to absolute gravity stations in the North Island and South Island. Gravity reprocessing was undertaken using Gsolve software using a Normal Least Squares fit to the data and usually a 99% residual confidence interval (McCubbine et al 2018). A mix of historic (late 1970s and 1980s) and modern observation data were used.…”

Section: The 2020 Revision With Ties To Absolute Gravity Stationsmentioning

confidence: 99%

“…Observation errors are reduced and blunders are usually identified with sufficient repeat readings. The Gsolve gravity reduction programme (McCubbine et al 2018) helps to isolate these errors and gravity meter tares (a shift in gravity meter baseline that is not related to meter drift).…”

Section: Differences Between Gravity Reference Stations 2020 and Earlmentioning

confidence: 99%

See 2 more Smart Citations

New Zealand gravity reference stations 2020: history and development of the gravity network

Stagpoole

Tontini

Woodward³

2021

New Zealand Journal of Geology and Geophysics

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Section: Gravity Meter Calibration Rangesmentioning

confidence: 99%

Section: The 2020 Revision With Ties To Absolute Gravity Stationsmentioning

confidence: 99%

See 1 more Smart Citation

New Zealand gravity reference stations 2020: history and development of the gravity network

Stagpoole

Tontini

Woodward³

2021

New Zealand Journal of Geology and Geophysics

Self Cite

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“…To determine an accurate value for absolute gravity, corrections must be made for instrumental drift and tares between calibrations (McCubbine et al, 2016;Schubert, 2015;Telford et al, 1990). To correct for drift and obtain absolute gravity at each observation point it is essential to occupy at least one site of established absolute gravity before and after the course of surveying.…”

Section: Relative and Absolute Gravity Measurementmentioning

confidence: 99%

“…The gravity network consists of ~40,000 gravity observations made by different institutions primarily using Lacoste and Romberg D and G relative gravity meters. All observations in the database are tied to the New Zealand Primary Gravity Network (Robertson and Reilly, 1960) by a method of least squares (McCubbine et al, 2016;Woodward and Carman, 1984).…”

Section: The New Zealand Gravity Networkmentioning

confidence: 99%

A gravity analysis of the Alpine Fault and the DFDP-2 drill site, Whataroa valley, South Westland, South Island, New Zealand

Jenkins¹

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<p>The second phase of drilling into the Alpine Fault (DFDP-2), was completed in the Whataroa River valley, a former glacial valley located in central Westland, South Island, New Zealand. The site is located next to a steep hillside on the hanging-wall, ~1 km southeast of the mapped surface trace of the Alpine Fault. Projection of the hillside suggests a sediment thickness of 100 ± 40 m at the drill site; however, the sediment thickness was approximately double pre-drill estimates. Additionally, the surface expression and shallow geometry of the Alpine Fault in the Whataroa River valley, is not well-defined due to post-glacial burial of the fault zone. This thesis describes a gravity study designed to better constrain sub-surface structure beneath the DFDP-2 drill site and across the Alpine Fault. During this study, 466 new high-precision gravity observations were collected (standard error = 0.015 mGal) and amalgamated with 134 existing gravity stations, yielding comprehensive coverage of gravity data across the study area. A high density of observations was achieved within pre-determined zones, in addition to regional measurements so that residual gravity anomaly maps could be produced. The maps reveal: a negative residual gravity anomaly interpreted as a dextrally-offset glacial channel at least 350-450 m deep; steep localised gravity gradients near the Alpine Fault and DFDP-2 drill site that are interpreted as faulted and/or eroded boundaries; and a negative gravity anomaly adjacent to the DFDP-2 drill site that is interpreted as the deepest point of an over-deepened glacial lake. Gravity models were used to estimate the bedrock-sediment interface geometry near the DFDP-2 drill site and Alpine Fault. Structural inversion of the density boundary next to the drill site suggests either a moderately-dipping reverse fault or sub-vertical erosional wall exists beneath the hillside. Additional constraints on physical properties from direct density measurements or seismic velocity determinations and direct constraints on sediment thickness and layer geometry from seismic surveys will in future allow this new high-precision gravity dataset to be modelled more effectively.</p>

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LTide - Matlab/Octave software tool for temporal and spatial analysis of tidal gravity acceleration effects according to Longman formulas

et al. 2019

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Tides have largest impact on gravity measurements compared to all other environmental effects. They are a direct result of the gravitational forces of the planetary bodies, mainly the Moon and the Sun. The magnitude of tidal effects depends on the relative position of planetary bodies around the Earth and can be computed from the astronomical ephemeris. In this paper, LTide software is presented, a lightweight application for computation of the tidal gravity acceleration effects according to Longman formulas. The software solves a problem of laborious calculations and simplifies the analysis of gravity data over any time period and any surveyed area worldwide. The code is open-sourced, platform independent, written in Matlab/Octave programming language. It has graphical user interface which offers several options for import, export and visualization of the results. The software is meant to be an easy-to-use tool for geoscientists and other users in processing relative gravity measurements and tempo-spatial analysis of tidal gravity effects.

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Gsolve, a Python computer program with a graphical user interface to transform relative gravity survey measurements to absolute gravity values and gravity anomalies

Cited by 15 publications

References 4 publications

New Zealand gravity reference stations 2020: history and development of the gravity network

New Zealand gravity reference stations 2020: history and development of the gravity network

A gravity analysis of the Alpine Fault and the DFDP-2 drill site, Whataroa valley, South Westland, South Island, New Zealand

LTide - Matlab/Octave software tool for temporal and spatial analysis of tidal gravity acceleration effects according to Longman formulas

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