Gravity Modeling of the Southern Madagascar Plateau

2017 ◽  
Author(s):  
B. Razafindrakoto ◽  
C. Raharimananirina ◽  
L. Pastor ◽  
H. Rakotondramano ◽  
T. Randriamiarantsoa
Keyword(s):  
Gravity Modeling

Imaging the Chicxulub Central Crater Zone from Large-Scale Seismic Acoustic Wave Propagation and Gravity Modeling

2021 ◽  
Author(s):  
Carlos Ortiz-Aleman ◽  
Ronald Martin ◽  
Jaime Urrutia-Fucugauchi ◽  
Mauricio Orozco del Castillo ◽  
Mauricio Nava-Flores
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Large Scale ◽  
Gravity Modeling ◽  
Acoustic Wave Propagation ◽  
Central Crater

2-D gravity modeling with analytically defined geometry and quadratic polynomial density functions

Geophysics ◽  
1999 ◽  
Vol 64 (6) ◽  
pp. 1730-1734 ◽  
Author(s):  
Beatriz Martín‐Atienza ◽  
Juan García‐Abdeslem
Keyword(s):  
Numerical Methods ◽  
Polynomial Function ◽  
Continuous Functions ◽  
Model Solution ◽  
Gravity Modeling ◽  
Density Functions ◽  
Gravity Effect ◽  
New Methods ◽  
Order Polynomial ◽  
Broad Variety

New methods for 2-D modeling of gravity anomaly data are developed following an approach that uses both analytic and numerical methods of integration. The forward‐model solution developed here is suitable to calculate the gravity effect caused by a 2-D source body bounded either laterally or vertically by continuous functions. In our models, the density contrast is defined by a second‐order polynomial function of depth and distance along the profile. We present several examples to show that our models are capable of accommodating a broad variety of geologic structures.

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 Geometry of the Deep Calabrian Subduction (Central Mediterranean Sea) From Wide‐Angle Seismic Data and 3‐D Gravity Modeling

2020 ◽  
Vol 21 (3) ◽  
Author(s):  
David Dellong ◽  
Frauke Klingelhoefer ◽  
Anke Dannowski ◽  
Heidrun Kopp ◽  
Shane Murphy ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Seismic Data ◽  
Gravity Modeling ◽  
Wide Angle ◽  
Central Mediterranean ◽  
Central Mediterranean Sea

scholarly journals Basement Mapping of the Fucino Basin in Central Italy by ITRESC Modeling of Gravity Data

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 398
Author(s):  
Federico Cella ◽  
Rosa Nappi ◽  
Valeria Paoletti ◽  
Giovanni Florio
Keyword(s):  
Seismic Activity ◽  
Site Response ◽  
Gravity Data ◽  
A Priori ◽  
Central Italy ◽  
Gravity Anomalies ◽  
Gravity Modeling ◽  
Ground Shaking ◽  
Sedimentary Evolution ◽  
Fucino Basin

Sediments infilling in intermontane basins in areas with high seismic activity can strongly affect ground-shaking phenomena at the surface. Estimates of thickness and density distribution within these basin infills are crucial for ground motion amplification analysis, especially where demographic growth in human settlements has implied increasing seismic risk. We employed a 3D gravity modeling technique (ITerative RESCaling—ITRESC) to investigate the Fucino Basin (Apennines, central Italy), a half-graben basin in which intense seismic activity has recently occurred. For the first time in this region, a 3D model of the Meso-Cenozoic carbonate basement morphology was retrieved through the inversion of gravity data. Taking advantage of the ITRESC technique, (1) we were able to (1) perform an integration of geophysical and geological data constraints and (2) determine a density contrast function through a data-driven process. Thus, we avoided assuming a priori information. Finally, we provided a model that honored the gravity anomalies field by integrating many different kinds of depth constraints. Our results confirmed evidence from previous studies concerning the overall shape of the basin; however, we also highlighted several local discrepancies, such as: (a) the position of several fault lines, (b) the position of the main depocenter, and (c) the isopach map. We also pointed out the existence of a new, unknown fault, and of new features concerning known faults. All of these elements provided useful contributions to the study of the tectono-sedimentary evolution of the basin, as well as key information for assessing the local site-response effects, in terms of seismic hazards.

scholarly journals THE GRAVITY MODEL FORMALIZATION FOR THE INTERCITY PASSENGER’S CORRESPONDENCES PARAMETER’S ESTIMATION

2017 ◽  
Vol 16 (5) ◽  
pp. 437-443 ◽  
Author(s):  
C. V. Dolya
Keyword(s):  
Gravity Model ◽  
Transportation System ◽  
Gravity Models ◽  
Gravity Modeling ◽  
Passenger Transport ◽  
Passenger Transportation ◽  
The Given ◽  
Selection Of ◽  
Calibration Coefficients

he paper considers a possibility to apply gravity models for calculation of intercity passenger transport corres- pondences which are implemented with the help of public transport. The Ukraine transportation system has been selected as an object of investigation and this approach extends application possibilities of the obtained results. Calibration coefficients used in calculation of the indicated correspondences are rather important and significant in case of forecasting passenger transport correspondences. Formalization of these factors is necessary for every transportation system if a calculation of pas-senger transport correspondences has been made for it. In this case searching for actual calibration parameters and other coef-ficients as components of gravitational models is a relevant objective of the given paper. Selection of the gravity model va- riant plays rather significant role in solution of this problem. The developed methods for calculation of passenger transport correspondences are proposed for their application in respect of various transport and trip types. The executed research works have made it possible to investigate a process pertaining to providing of services for passenger transportation while using public routes. The obtained characteristics on functioning of the studied system have allowed to assess the possibility for ap-plication of the known methods for calculation of passenger correspondences and analyze the quality of their application. Calibration coefficients have been empirically selected for calculation of the indicated correspondences while using method of gravity modeling. Formalization of previously unexplored parameters of gravity model component provides the possibility to apply the considered approach for calculation of passenger correspondences within the framework of the investigated trans-portion system. This makes it possible to plan and arrange interaction of various transport types and provides new data and knowledge on the studied system.

3D Gravity modeling of the volcanic island of Surtsey, Iceland

2021 ◽  
Author(s):  
sara sayyadi ◽  
Magnús T. Gudmundsson ◽  
Thórdís Högnadóttir ◽  
James White ◽  
Joaquín M.C. Belart ◽  
...  
Keyword(s):  
Sea Level ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Gravity Modeling ◽  
Gravity Station ◽  
Effusive Activity ◽  
3D Gravity ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Drill Cores

<p>The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones.  Constraints on the subsurface structure of Surtsey achieved mainly based on the documented evolution during eruption and from drill cores in 1979 and in the ICDP-supported SUSTAIN drilling expedition in 2017(an inclined hole, directed 35° from the vertical). The 2017 drilling confirmed the existence of a diatreme, cut into the sedimentary pre-eruption seafloor (Jackson et al., 2019). </p><p>We use 3D-gravity modeling, constrained by the stratigraphy from the drillholes to study the structure of the island and the underlying diatreme.  Detailed gravity data were obtained on Surtsey in July 2014 with a gravity station spacing of ~100 m. Density measurements for the seafloor sedimentary and tephra samples of the surface were carried out using the ASTM1 protocol. By comparing the results with specific gravity measurements of cores from drillhole in 2017, a density contrast of about 200 kg m<sup>-3</sup> was found between the lapilli tuffs of the diatreme and the seafloor sediments.  Our approach is to divide the island into four main units of distinct density: (1) tuffs above sea level, (2) tuffs below sea level, (3) lavas above sea level, and (4) a lava delta below sea level, composed of breccias over which the lava advanced during the effusive eruption.  The boundaries between the bodies are defined from the eruption history and mapping done during the eruption, aided by the drill cores. </p><p>A complete Bouguer anomaly map is obtained by calculating a total terrain correction by applying the Nagy formula to dense DEMs (5 m spacing out to 1.2 km from station, 200 m spacing between 1.2 km and 50 km) of both island topography and ocean bathymetry.  Through the application of both forward and inverse modeling, using the GM-SYS 3D software, the results provide a 3-D model of the island itself, as well as constraints on diatreme shape and depth.</p>

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