| Gravity provides unique information about the deep earth that is unattainable in any other way. Small changes in the gravity field reflect density contrasts at depth that hold clues to deep crustal structure, to anomalous ore bodies, to the compensation of lithospheric loads, to the figure of the earth.;In the nearly 75 years since the first measurement of gravity from a submarine, gravimeters have been placed on a variety of moving platforms including surface ships, aircraft, nuclear submarines and submersibles. Airborne gravimetry is an important new technique within this field, because of an aircraft's ability to survey regions remote or inaccessible by other means.;Airborne gravimetry has become a viable tool in the last 10-12 years because of the development of methods of precise aircraft positioning, and efforts continue to reduce the error in this technique. In this thesis, I examine the theory behind the technique of measuring gravity from a moving platform, in terms of what a moving gravimeter can measure, and a complete theoretical development of the Eotvos correction. An in-depth examination of processing and filtering techniques for airborne work shows that the choice of lowpass filters employed with these data can have a significant impact on the quality of the final free-air gravity anomaly. Finally, a method for removing error introduced by aircraft-induced horizontal accelerations is tested and shown to be only partially successful in reducing this source of error.;The last section of the thesis shows an application where gravity collected from a ship is used to constrain a flexural model of lithospheric faulting describing compressional deformation in oceanic lithosphere. The models show that the mechanical properties of the lithosphere at these two faulted features are consistent with those observed at other compressional features, such as subduction zones. The lithosphere at one feature is somewhat weaker than expected, although not when the degree of plate curvature is taken into account. Gravity is the one tool that can provide these answers. |
