The Comparison of Gravity Anomalies based on Recent High-Degree Global Models

Yılmaz, Mustafa; Kozlu, Bürhan

doi:10.5578/fmbd.67502

Cited by 7 publications

(3 citation statements)

References 19 publications

(26 reference statements)

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“…Figure 6 refers to a vertical gradient of normal gravity as an approximation in which a gravity measurement point, which is almost never placed on the reference ellipsoid's surface, is adjusted according to geophysical corrections [88,89]. The details regarding the distribution of vertical gravity values over Venezuela, Trinidad, and Tobago showed that the lowest values (below −100 mGal) mostly correspond to the extreme amplitude of topographic changes, e.g., the abrupt borders between the mountains/hills and the margins of the bathymetric depression, while the highest values (over 100 mGal) were detected on the tops of the mountains, which corresponded well with the local geomorphology of the region.…”

Section: Resultsmentioning

confidence: 99%

Seismotectonics of Shallow-Focus Earthquakes in Venezuela with Links to Gravity Anomalies and Geologic Heterogeneity Mapped by a GMT Scripting Language

Lemenkova

Debeir

2022

Sustainability

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This paper presents a cartographic framework based on algorithms of GMT codes for mapping seismically active areas in Venezuela. The data included raster grids from GEBCO, EGM-2008, and vector geological layers from the USGS. The data were iteratively processed in the console of GMT, converted by GDAL, formatted, and mapped for geophysical data visualisation; the QGIS was applied for geological mapping. We analyzed 2000 samples of the earthquake events obtained from the IRIS seismic database with a 25-year time span (1997–2021) in order to map the seismicity. The approach to linking geological, topographic, and geophysical data using GMT scripts aimed to map correlations among the geophysical phenomena, tectonic processes, geological setting, seismicity, and earthquakes. The practical application of the GMT scripts consists in automated mapping for the visualization of geological risks and hazards in the mountainous region of the Venezuelan Andes. The proposed method integrates the approach of GMT scripts with state-of-the-art GIS techniques, which demonstrated its effectiveness as a tool for mapping spatial datasets and rapid data processing in an iterative regime. In this context, using GMT and GIS to find similarities between the regional earthquake distribution and the geological and topographic setting is essential for hazard risk assessment. This study can serve as a basis for predictive seismic analysis in geologically vulnerable regions of Venezuela. In addition to a technical demonstration of GMT algorithms, this study also contributes to geological and geophysical mapping and seismic hazard assessments in South America. We present the full scripts used for mapping in a GitHub repository.

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Section: Resultsmentioning

confidence: 99%

Seismotectonics of Shallow-Focus Earthquakes in Venezuela with Links to Gravity Anomalies and Geologic Heterogeneity Mapped by a GMT Scripting Language

Lemenkova

Debeir

2022

Sustainability

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“…The gravity anomaly residuals and the total number of selected points were used to compute the RMSE. The Root Mean Square Error, RMSE was computed using the formula given by Yilmaz and Kozlu (2018);…”

Section: Validation Of the Interpolated Gravity Datamentioning

confidence: 99%

Measurement and Enhancement of Gravity Data for Geophysical Investigations in Abuja, Nigeria

Abubakar,

Olumba

2024

FJS

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The availability of gravity data is useful to individuals, governments and organizations that wish to carry out a geophysical investigation in Abuja. The data provides an accurate model for environmental monitoring and disaster studies. This research was aimed at measurement and prediction of gravity data in Abuja, Nigeria. The aim was achieved by observation of terrestrial gravity data at forty (40) gravity stations around the federal capital territory Abuja, prediction of the gravity data at other points and the evaluation of the predicted data. Gravity reduction was carried out on the measured data to account for drift correction, free air correction, bouguer correction latitude correction and terrain correction. The data was further enhanced by interpolation using the Kriging method. A total of 59 points were predicted from the 40 measured stations. The predicted gravity anomalies were validated by comparing with their corresponding gravity anomalies obtained from the Earth Gravity Model 2008 (EGM08) because of their well-established reliability. For the number of observations, n = 59, the RMSE and SE were computed as 4.797mGal (4.787x10-5 ms-2) and 4.880mGal (4.880 x10-5 ms-2) respectively. Also, the correlation value obtained was 0.991 which is significant at 0.01 level. This shows a strong relationship signifying a perfect possible agreement in the values obtained. It was therefore concluded that Kriging is a good interpolator that provides an estimate with high reliability and dependency. In this regard, considering the high cost of geophysical data collection, gravity prediction can make geophysical data collection more efficient and cost-effective.

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“…Here, the accuracy of the model varies inversely to the computed value of the RMSE [21]. The Root Mean Square Error, RMSE index used for the computation of the geometric geoid model accuracy as given by Yilmaz and Kozlu [22] is…”

Section: Accuracy Of the Modelmentioning

confidence: 99%

Establishment of local geometric geoid model for Busoga, Uganda

Kyamulesire¹,

Okiemute²,

Oluyori³

2020

World J. Adv. Res. Rev.

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The importance of the local geoid model for the computation of accurate geoid heights, as well as orthometric heights used for engineering constructions, necessitated its establishment in areas, regions or countries. Consequently, this study establishes the local geometric geoid model of Busoga, Uganda, using the geometric method. A total of 26 points were used in the study, 20 points for the development of the model and 6 test points. GNSS observations were acquired with Trimble GNSS dual-frequency receivers and processed with Bernese (V5.2) and Spectra Precision Survey Office (v4.1) software to obtain the coordinates and ellipsoidal heights of the points. Differences between the existing orthometric and ellipsoidal heights were computed to obtain the geoid heights. The Least squares adjustment technique was applied to determine the fit, as well as the Bicubic and Multiquadratic models’ parameters. The Root Mean Squares Error (RMSE) index was used to compute the accuracy of the models. The geoid models were compared with their RMSE, as well as accuracy to determine which of them is more suitable for application in the study area. The comparison result shows that the Multiquadratic geoid model is more suitable for implementation in the study area. A Microsoft Excel program was developed for the application of the model in the study area.

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The Comparison of Gravity Anomalies based on Recent High-Degree Global Models

Cited by 7 publications

References 19 publications

Seismotectonics of Shallow-Focus Earthquakes in Venezuela with Links to Gravity Anomalies and Geologic Heterogeneity Mapped by a GMT Scripting Language

Seismotectonics of Shallow-Focus Earthquakes in Venezuela with Links to Gravity Anomalies and Geologic Heterogeneity Mapped by a GMT Scripting Language

Measurement and Enhancement of Gravity Data for Geophysical Investigations in Abuja, Nigeria

Establishment of local geometric geoid model for Busoga, Uganda

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