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Potential theory in gravity and magnetic applications
01 Jan 1995-
TL;DR: In this article, the potential of the geomagnetic field has been studied in vector calculus, and the results of the potential have been shown to be equivalent to the conversion of units.
Abstract: Introduction 1. The potential 2. Consequences of the potential 3. Newtonian potential 4. Magnetic potential 5. Magnetization 6. Spherical harmonic analysis 7. Regional gravity fields 8. The geomagnetic field 9. Forward method 10. Inverse method 11. Fourier-domain modeling 12. Transformations A. Review of vector calculus B. Subroutines C. Review of sampling theory D. Conversion of units.
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TL;DR: The magnetic method is the primary exploration tool in the search for minerals, oil and gas, geothermal resources, and groundwater, and for a variety of other purposes such as natural hazards assessment, mapping impact structures, and engineering and environmental studies as discussed by the authors.
Abstract: The magnetic method, perhaps the oldest of geophysical exploration techniques, blossomed after the advent of airborne surveys in World War II. With improvements in instrumentation, navigation, and platform compensation, it is now possible to map the entire crustal section at a variety of scales, from strongly magnetic basement at regional scale to weakly magnetic sedimentary contacts at local scale. Methods of data filtering, display, and interpretation have also advanced, especially with the availability of low-cost, high-performance personal computers and color raster graphics. The magnetic method is the primary exploration tool in the search for minerals. In other arenas, the magnetic method has evolved from its sole use for mapping basement structure to include a wide range of new applications, such as locating intrasedimentary faults, defining subtle lithologic contacts, mapping salt domes in weakly magnetic sediments, and better defining targets through 3D inversion. These new applications have increased the method’s utility in all realms of exploration — in the search for minerals, oil and gas, geothermal resources, and groundwater, and for a variety of other purposes such as natural hazards assessment, mapping impact structures, and engineering and environmental studies.
467 citations
University of Colorado Boulder1, National Oceanic and Atmospheric Administration2, Institute for Geosciences and Natural Resources3, GNS Science4, United States Naval Research Laboratory5, U.S. National Geodetic Survey6, Geological Survey of Canada7, University of Leeds8, United States Geological Survey9, Ohio State University10, University of Potsdam11, Geoscience Australia12, King Saud University13, University of Sydney14, Institut de Physique du Globe de Paris15, National Institute of Geophysics and Volcanology16
TL;DR: In this article, a global Earth Magnetic Anomaly Grid (EMAG2) has been compiled from satellite, ship, and airborne magnetic measurements, both over land and the oceans, where the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids.
Abstract: [1] A global Earth Magnetic Anomaly Grid (EMAG2) has been compiled from satellite, ship, and airborne magnetic measurements. EMAG2 is a significant update of our previous candidate grid for the World Digital Magnetic Anomaly Map. The resolution has been improved from 3 arc min to 2 arc min, and the altitude has been reduced from 5 km to 4 km above the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latest CHAMP satellite magnetic field model MF6. EMAG2 is available at http://geomag.org/models/EMAG2 and for permanent archive at http://earthref.org/cgi-bin/er.cgi?s=erda.cgi?n=970.
455 citations
TL;DR: The bottom of the magnetized crust determined from the spectral analysis of residual magnetic anomalies is generally interpreted as the level of the Curie point isotherm as mentioned in this paper, and a method to estimate the depth extent of magnetic sources was applied to the magnetic anomalies of East and Southeast Asia.
395 citations
TL;DR: A review of the application of nitrogen-vacancy (NV) magnetometry to the exploration of condensed matter physics can be found in this article, focusing on its use to study static and dynamic magnetic textures and dynamic current distributions.
Abstract: The magnetic fields generated by spins and currents provide a unique window into the physics of correlated-electron materials and devices. First proposed only a decade ago, magnetometry based on the electron spin of nitrogen-vacancy (NV) defects in diamond is emerging as a platform that is excellently suited for probing condensed matter systems; it can be operated from cryogenic temperatures to above room temperature, has a dynamic range spanning from direct current to gigahertz and allows sensor–sample distances as small as a few nanometres. As such, NV magnetometry provides access to static and dynamic magnetic and electronic phenomena with nanoscale spatial resolution. Pioneering work has focused on proof-of-principle demonstrations of its nanoscale imaging resolution and magnetic field sensitivity. Now, experiments are starting to probe the correlated-electron physics of magnets and superconductors and to explore the current distributions in low-dimensional materials. In this Review, we discuss the application of NV magnetometry to the exploration of condensed matter physics, focusing on its use to study static and dynamic magnetic textures and static and dynamic current distributions. The spin of the nitrogen-vacancy (NV) defect in diamond acts as a sensitive, atomic-sized magnetic field sensor that provides nanoscale access to the properties of condensed matter systems. This Review introduces NV magnetometry and discusses its application to the exploration of static and dynamic magnetism and electric current distributions.
389 citations
01 Jan 2015
TL;DR: A general review of the mathematical formalism that is used in describing gravity and topography of the terrestrial planets is given in this article, where the basic properties of Earth, Venus, Mars, Mercury, and the Moon are characterized.
Abstract: This chapter reviews our current knowledge of the gravity and topography of the terrestrial planets and describes the methods that are used to analyze these data. A general review of the mathematical formalism that is used in describing gravity and topography is first given. Next, the basic properties of Earth, Venus, Mars, Mercury, and the Moon are characterized. Following this, the relationship between gravity and topography is quantified, and techniques by which geophysical parameters can be constrained are detailed. Analysis methods include crustal thickness modeling, geoid/topography ratios, spectral admittance and correlation functions, and localized spectral analysis and wavelet techniques. Finally, the major results that have been obtained by modeling the gravity and topography of Earth, Venus, Mars, Mercury, and the Moon are summarized.
301 citations