Application of three‐dimensional interactive modeling in gravity and magnetics

Goetze, H.; Lahmeyer, B.

doi:10.1190/1.1442546

Cited by 316 publications

(153 citation statements)

References 8 publications

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“…The system uses polyhedrons with triangulated surfaces to approximate bodies of density and/or magnetic susceptibility within the Earth's crust and mantle, the geometries of which are defined by a number of parallel vertical modeling sections [Götze and Lahmeyer, 1988]. The positions of the 35 vertical model sections used here are chosen to be parallel to the north-south seismic profile (A-P-A′-A″ in Figure 1; see Figure 3 for the P wave velocity distribution).…”

Section: Methods and Constraining Datamentioning

confidence: 99%

Three‐dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area

Choi

Götze

2013

JGR Solid Earth

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[1] Here we use the global gravity field data set EGM2008 for 3-D crustal density modeling of the Mount Paekdu stratovolcano and surrounding area located on the border between North Korea and China. Curvature analysis and Euler deconvolution are used to assist interpretation, and the 3-D model is constrained by multiple geological and geophysical data sets. Mount Paekdu is characterized by a low Bouguer anomaly of À110 × 10 À5 m/s 2 , which is caused by the combined gravity effects of (1) a depth to the Moho of about 40 km, (2) a zone with lower P wave velocity and density than the surrounding, (3) low density volcanic rocks on the surface, and (4) the presence of a magma chamber that has not previously been identified. The modeled magma chamber has a mean thickness of 5 km and a density of about 2350 kg/m 3 and is located <10 km from the surface. Magma chambers are also modeled beneath Mount Wangtian and Mount Nampotae. However, the results of the 3-D density modeling do not confirm the existence of a previously proposed midcrustal low-velocity zone in the area 70 km to the north of Mount Paekdu. Since the Pliocene, volcanic activity in the Mount Paekdu region has migrated from the east coast of North Korea to the northwest, following the path of NW-SE trending faults.

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Section: Methods and Constraining Datamentioning

confidence: 99%

Three‐dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area

Choi

Götze

2013

JGR Solid Earth

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“…Gravity modelling was carried out with the programme IGMAS, which is an interactive, graphical computer system for the interpretation of potential field data in 3D (Götze and Lahmeyer, 1988). Geological structures are defined as polygons along parallel working planes.…”

Section: Gravity Modellingmentioning

confidence: 99%

Deep structure of the western South African passive margin — Results of a combined approach of seismic, gravity and isostatic investigations

2009

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The passive margin of the South Atlantic shows typical features of a rifted volcanic continental margin, encompassing seaward dipping reflectors, continental flood basalts and high-velocity/density lower crust at the continentocean transition, probably emplaced during initial seafloor spreading in the Early Cretaceous.The Springbok profile offshore western South Africa is a combined transect of reflection and refraction seismic data. This paper addresses the analysis of the seismic velocity structure in combination with gravity modelling and isostatic modelling to unravel the crustal structure of the passive continental margin from different perspectives.The velocity modelling revealed a segmentation of the margin into three distinct parts of continental, transitional and oceanic crust. As observed at many volcanic margins, the lower crust is characterised by a zone of high velocities with up to 7.4 km/s. The conjunction with gravity modelling affirms the existence of this body and at the same time substantiated its high densities, found to be 3100 kg/m³. Both approaches identified the body to have a thickness of about 10 km. Yet, the gravity modelling predicted the transition between the highdensity body towards less dense material farther west than initially anticipated from velocity modelling and confirmed this density gradient to be a prerequisite to reproduce the observed gravity signal. 2Finally, isostatic modelling was applied to predict average crustal densities if the margin was isostatically balanced. The results imply isostatic equilibrium over large parts of the profile, smaller deviations are supposed to be compensated regionally. The calculated load distribution along the profile implies that all pressures are hydrostatic beneath a depth of 45 km.3

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“…The model of the three-dimensional density structure was achieved through forward modeling using the software IGMAS+ (Schmidt et al, 2010). This software is based on the approximation of threedimensional bodies by means of polyhedra, according to Götze (1976) and Götze & Lahmeyer (1988). The modeling is carried out interactively by creating cross-sections from which the polyhedra are calculated from the input of vertices.…”

Section: Modeling Of the Structure Of The Forearc And Subduction Zonementioning

confidence: 99%

Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

Lücke¹

2015

Rev. Geol. Amér. Central

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ABSTRACT:The forearc region along the Central American Subduction Zone shows a series of trench-parallel positive gravity anomalies with corresponding gravity lows along the trench and toward the coast. These features extend from Guatemala to northern Nicaragua. However, the Costa Rican section of the forearc does not follow this pattern due to the segmentation of the along-trench gravity low, the absence of the coastal low, and the presence of emerged continental mass along the forearc gravity high at the Nicoya Peninsula. Geodetic and seismological studies along the Costa Rican Subduction Zone suggest the presence of coupled areas in the seismogenic zone beneath the Nicoya Peninsula prior to the 7.6 Mw magnitude earthquake of September 5th, 2012. These areas have previously been associated with asperities. Based on the structure of the overriding plate, former publications have proposed a mechanical model for the origin of asperities along the Chilean convergent margin, in which the dense igneous material in the forearc of the overriding plate above the seismogenic zone modifies/disturbs the state of static stress and influences seismogenic processes. In Costa Rica, surface geology and gravity data indicate the existence of dense basalt/gabbro crust overlying the seismogenic zone where the coupling is present. Bouguer anomaly values in this region reach up to 120×10 -5 m/s 2 and are the highest for Costa Rica. In this research, the state of static stress on the Cocos-Caribbean plate interface is calculated based on the geometry and on the density distribution of a 3D litosphere density model of the subduction zone as interpreted from gravity data from combined geopotential models. Results show a spatial correlation between the coupled areas at the Nicoya Peninsula and the presence of anomalies on the static state of stress on the plate interface. The stress anomalies were calculated for the normal component of the vertical stress on the seismogenic zone and were interpreted as being generated by the dense material which makes up the forearc in the area.

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Application of three‐dimensional interactive modeling in gravity and magnetics

Cited by 316 publications

References 8 publications

Three‐dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area

Three‐dimensional density modeling of the EGM2008 gravity field over the Mount Paekdu volcanic area

Deep structure of the western South African passive margin — Results of a combined approach of seismic, gravity and isostatic investigations

Estado de esfuerzos estáticos en la interface de placas Coco-Caribe en Costa Rica: Interpretación mecánica para el origen de asperezas en la zona sismogénica

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