scholarly journals Analysis of gravity anomaly and seismicity in Bali region

2021 ◽  
Vol 5 (3) ◽  
pp. 34-43
Author(s):  
Alfha Abrianto L. Tobing ◽  
I Ketut Sukarasa ◽  
Mahmud Yusuf
Keyword(s):  
Gravity Anomaly ◽  
Bouguer Anomaly ◽  
Secondary Data ◽  
Coefficient Of Determination ◽  
Satellite Gravity ◽  
Mapping Tool ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Gravity Interpretation ◽  
Earthquake Data

This study aims to determine the value of the gravity anomaly in the Bali region, identify the fault structure in the Bali region using gravity interpretation and analyze the relationship between gravity anomaly and seismicity in the Bali region. The data used is secondary data, namely satellite gravity anomaly data obtained from the topex website and earthquake data obtained from the Indonesian Agency for Meteorological, Climatological, and Geophysics (BMKG) catalog. Data processing in this study was done using gravity and Second Vertical Derivative (SVD) methods. We used Surfer15 software, Oasis Montaj, and the Generic Mapping Tool (GMT). The results of the complete Bouguer anomaly map show the anomalous value of the study area between 10-220 mGal, regional anomaly 40-190 mGal, and the residual anomaly between (-120)-60 mGal. Judging from the SVD contour map that has included earthquake data in the Bali region for the 2008-2020 period, the type of fault in the Seririt Fault, Tejakula Fault, and Fault around Mount Agung is a thrust fault. Judging from the value of the coefficient of determination, it shows that 99% of the seismicity value is influenced by gravity anomaly. The higher the value of the gravity anomaly, the higher the seismicity value.

scholarly journals New Bouguer Anomaly Map for the Territory of the Slovenia

2021 ◽  
Vol 13 (22) ◽  
pp. 4510
Author(s):  
Klemen Medved ◽  
Oleg Odalović ◽  
Božo Koler
Keyword(s):  
Gravity Anomaly ◽  
Significant Influence ◽  
Bouguer Anomaly ◽  
High Quality ◽  
Digital Terrain ◽  
Terrain Models ◽  
Gravimetric Data ◽  
The Republic ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

The existing Bouguer anomaly map, which covers the territory of the Republic of Slovenia is a few decades old. Since then, quite a few new gravimetric measurements (data) for the territory of Slovenia as well as high quality digital terrain models that are needed for creating such a map have been made available. The methodology and standards for creating gravity anomaly maps are also changing. Thus, the national Bouguer anomaly map was updated. There were some gross errors detected in the set of old gravimetric data. Additionally, the influence of new updated gravimetric data was analyzed. The comparison of the various maps and the analysis of the influence of input gravimetric data indicates that the new gravimetric data of Slovenia has a significant influence on the creation of the gravimetric anomaly maps for Slovenia (even over 30 mGals at some points).

An updated Bouguer anomaly map of south‐central West Africa

Geophysics ◽  
1983 ◽  
Vol 48 (8) ◽  
pp. 1120-1128 ◽  
Author(s):  
David A. Hastings
Keyword(s):  
Gravity Anomaly ◽  
Field Data ◽  
Bouguer Anomaly ◽  
Mineral Deposits ◽  
Bouguer Gravity ◽  
Western Africa ◽  
South Central ◽  
Eburnean Orogeny ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

A new Bouguer gravity anomaly map compiled for western Africa adds data for Ghana, Guinea, and Liberia. The new data add detail to a key part of the Eburnean shield and assist in the development of a model of rifting at the time of the Eburnean orogeny, 2000 million years ago. This model includes a framework for the deposition of the region’s mineral deposits. The model and existing field data can be used to guide future minerals exploration in the region.

Gravity interpretation of Raguba field, Sirte basin, Libya

Geophysics ◽  
1980 ◽  
Vol 45 (7) ◽  
pp. 1153-1163 ◽  
Author(s):  
Salah I. El‐Batroukh ◽  
Ahmed S. Zentani
Keyword(s):  
Bouguer Anomaly ◽  
Oil Field ◽  
Gravity Models ◽  
The North ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Sirte Basin ◽  
Surrounding Areas ◽  
Gravity Interpretation ◽  
Field Area

A Bouguer anomaly map of Raguba oil field and the surrounding areas is presented and interpreted. The main features of the map are: (1) A belt of positive anomalies approaching Bouguer values of 3 mgal in the field area then increasing up to 9 mgal toward the northwest. (2) Negative Bouguer values of −20 mgal on the east and west sides and a negative value of −13 mgal on the northeast side of the field. (3) Steep anomaly gradients trending north‐south on both sides of the field. To the north, the trend takes a northwest direction. (4) All these anomalies are superimposed on a regional trend of 0.16 mgal/km negative toward the south. The positive belt is interpreted as a horst structure characterized by crystalline basement at shallow depths. The negative anomalies are due to the density contrast between the sediments and the basement. Structural sections along certain profiles are presented and used for constructing gravity models calculated by computer.

scholarly journals Combination of Terrestrial and Satellite Gravity Data for the Characterization of the Southwestern Coastal Region of Cameroon: Appraisal for Hydrocarbon Exploration

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Paul Gautier Kamto ◽  
Willy Lemotio ◽  
Alain-Pierre Kamga Tokam ◽  
Loudi Yap
Keyword(s):  
Gravity Data ◽  
Bouguer Anomaly ◽  
Coastal Region ◽  
Hydrocarbon Exploration ◽  
Horizontal Gradient ◽  
Target Area ◽  
Satellite Gravity ◽  
Area Of Interest ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

The southwestern coastal region of Cameroon is an area of interest because of its hydrocarbon potential (gas and oil). Terrestrial and satellite gravity data were combined and analyzed to provide a better precision in determining the structure of the study area. Firstly, the two gravity databases (in situ and satellite) have been coupled and validated using the least square collocation technique. Then, spectral analysis was applied to the combined Bouguer anomaly map to evaluate the thickness of sediments in some localities. We found that the sedimentary cover of the southwestern coastal region of Cameroon has a thickness that varies laterally from 1.68 ± 0.08 to 2.95 ± 0.15   km , especially in the western part. This result confirms that our target area is a potential site for hydrocarbon exploration. The horizontal gradient method coupled with the upward continuation at variable heights has been used to highlight several lineaments and their directions (N-S, E-W, SW-NE, and SSW-NNE). Lineaments trending in an N-S orientation are predominant. The Euler deconvolution method was also applied to the Bouguer anomaly map to determine the position, orientation, and depth of the different superficial faults of the study area. It appears that the majority of superficial faults have an N-S and SSW-NNE orientation. These directions are correlated with those previously highlighted by the maxima of horizontal gradient. The structural map could be used for a better identification of the direction of fluid flow within the subsurface or to update the geological map of our study area.

scholarly journals The Bouguer Anomaly Map of Iraq According to a New Local Theoretical Gravity Equation and Its Geological Importance

2020 ◽  
pp. 1392-1400
Author(s):  
Ahmed S. Al-Banna ◽  
Salar S. Al- Karadaghi ◽  
Hamed H. Abdullah
Keyword(s):  
Gravity Anomaly ◽  
Bouguer Anomaly ◽  
Sedimentary Basins ◽  
Gravity Equation ◽  
Base Stations ◽  
Western Boundary ◽  
Basement Rocks ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Bouguer Map

Four hundred and seventy eight gravity base stations in Iraq were used to obtain a new local theoretical gravity equation. The obtained equation was used to construct a Bouguer anomaly map of Iraq depending on the available gravity base stations. This map was compared with the Bouguer map constructed for the same stations using the international formula (1930). Good similarity in shapes and locations of the anomaly were observed, while the   gravity anomaly values in the new map were increased by about 30 mGal. The eastern zero gravity contour line of the new obtained gravity map coincides with the western  boundary of the tectonic Mesopotamian zone, while the main negative  gravity values coincide with the Mesopotamian area, which contains most oil fields in eastern Iraq. All negative gravity anomaly areas coincide with the deepest basement rocks (the sedimentary basins) in Iraq. The obtained results are very valuable in geological applications.

Tectonic insight and 3-D modelling of the Lusi (Java, Indonesia) mud edifice through gravity analyses

2021 ◽  
Vol 225 (2) ◽  
pp. 984-997
Author(s):  
Álvaro Osorio Riffo ◽  
Guillaume Mauri ◽  
Adriano Mazzini ◽  
Stephen A Miller
Keyword(s):  
Risk Mitigation ◽  
Bouguer Anomaly ◽  
Geological Model ◽  
Resource Exploitation ◽  
Subsurface Structures ◽  
Central Java ◽  
Geostatistical Interpolation ◽  
Gravity Response ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

SUMMARY Lusi is a sediment-hosted hydrothermal system located near Sidoarjo in Central Java, Indonesia, and has erupted continuously since May 2006. This mud eruption extends over a surface of ∼7 km2, and is framed by high containment dams. The present study investigates the geometry of the subsurface structures using a detailed gravimetric model to visualize in 3-D the Lusi system and surrounding lithologies. The obtained residual Bouguer anomaly map, simulated through geostatistical interpolation methods, supports the results of previous deformation studies. The negative gravity anomaly zones identified at Lusi are interpreted as fractured areas through which fluids can ascend towards the surface. A 3-D detailed geological model of the area was constructed with Geomodeller™ to highlight the main features. This model relies on the structures’ density contrasts, the interpreted residual Bouguer anomaly map, and geological data from previous authors. 3-D algorithms were used to calculate the gravity response of the model and validate it by inverse methods. The final output is a gravity constrained 3-D geological model of the Lusi mud edifice. These results provide essential details on the Lusi subsurface and may be useful for possible future geothermal resource exploitation and for the risk mitigation plans related to the maintenance of the man-made framing embankment.

scholarly journals Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

2017 ◽  
Vol 47 (1) ◽  
pp. 3-19
Author(s):  
João Gabriel Motta ◽  
Norberto Morales ◽  
Walter Malagutti Filho
Keyword(s):  
Bouguer Anomaly ◽  
Shear Zones ◽  
Magnetic Data ◽  
Gravity Modeling ◽  
West Gondwana ◽  
Fold And Thrust Belt ◽  
Fold Belts ◽  
Thrust Sheets ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

ABSTRACT: The Brasília and Ribeira fold belts have been established in south-southwestern São Francisco Craton during the Brasiliano-Pan African orogeny (0.9-0.5 Ga - Tonian to Cambrian), and played an important role in West Gondwana continent assembly. The region is given by a complex regional fold and thrust belt superposed by shearing during the orogeny late times, with superposing stress fields forming a structural interference zone. These thrust sheets encompasses assemblies from lower- to upper-crust from different major tectonic blocks (Paranapanema, São Francisco), and newly created metamorphic rocks. Re-evaluation of ground gravity datasets in a geologically constrained approach including seismology (CRUST1 model) and magnetic data (EMAG2 model) unveiled details on the deep- crust settings, and the overall geometry of the structural interference zone. The Simple Bouguer Anomaly map shows heterogeneous density distribution in the area, highlighting the presence of high-density, high metamorphic grade rocks along the Alterosa suture zone in the Socorro-Guaxupé Nappe, lying amid a series of metasedimentary thrust scales in a regional nappe system with important verticalization along regional shear zones. Forward gravity modeling favors interpretations of structural interference up North into Guaxupé Nappe. Comparison to geotectonic models shows similarities with modern accretionary belts, renewing the discussion.

scholarly journals Geometrical Characterisation of the Mamfe Basin, Cameroon, from the Earth, Gravitational Model (EGM 2008)

2018 ◽  
Vol 7 (1) ◽  
pp. 94
Author(s):  
Anatole Eugene Djieto Lordon ◽  
Mbohlieu YOSSA ◽  
Christopher M Agyingi ◽  
Yves Shandini ◽  
Thierry Stephane Kuisseu
Keyword(s):  
Average Length ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Igneous Rocks ◽  
Average Depth ◽  
The Earth ◽  
Gravitational Model ◽  
Petroleum Generation ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

Gravimetric studies using the ETOPO1-corrected high resolution satellite-based EGM2008 gravity data was used to define the surface extent, depth to basement and shape of the Mamfe basin. The Bouguer anomaly map was produced in Surfer 11.0. The Fast Fourier Transformed data was analyzed by spectral analysis to remove the effect of the regional bodies in the study area. The residual anomaly map obtained was compared with the known geology of the study area, and this showed that the gravity highs correspond to the metamorphic and igneous rocks while the gravity lows match with Cretaceous sediments. Three profiles were drawn on the residual anomaly map along which 2D models of the Mamfe basin were drawn. The modeling was completed in Grav2dc v2.06 software which uses the Talwini’s algorithm and the resulting models gave the depth to basement and the shape of the basement along the profiles. After processing and interpretation, it was deduced that the Mamfe basin has an average length and width of 77.6 km and 29.2 km respectively, an average depth to basement of 5 km and an overall U-shape basement. These dimensions (especially the depth) theoretically create the depth and temperature conditions for petroleum generation. 

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