HR: 14:00h
AN: GP53A-01 INVITED     [Abstracts]
TI: Multiple joint inversion of gravity, magnetic, electromagnetic and seismic data under a common structural framework for subsurface material discrimination
AU: * Gallardo, L A
EM: lgallard@cicese.mx
AF: Earth Science Division, CICESE, km 107 Carretera Tijuana-Ensenada, Ensenada, B.C 22860, Mexico
AB: The combined analysis of multiple geophysical observations on geological targets makes possible the discrimination and classification of subsurface materials and processes. Unfortunately, the individual uncertainties and low resolution of some data may mislead the integrated interpretation. It is now emerging that some of these limitations can be reduced in a joint inversion process by adopting the basic principle that collocated measurements should be influenced by a common underlying geology. A joint inversion approach that has been increasingly popular is that based on cross-gradient constraints; this approach basically seeks collocated subsurface images of two physical properties with a common structural signature defined by parallel property changes. This methodology has been successfully applied to the joint inversion of electromagnetic and seismic data; however, it has not yet been applied to geopotential data, which are thought to suffer from more severe limitations in resolution. As gravity and magnetic data constitute the geophysical evidence of two very characteristic properties of the subsurface materials, it is desirable to extend the cross-gradient philosophy to the joint inversion of geopotential data. This will address some relevant issues such as: Should several physical properties, like density and magnetization, follow a common underlying structural framework in actual geological terrains? If so, how much can geopotential data contribute to the search for such a common structure? Conversely, can the estimations of density and magnetization, as well as other physical parameters, be more accurate when a common structure is adopted? To address these questions, I developed a multiple joint inversion procedure founded on a generalized cross- gradient constraint that incorporates gravity, magnetic, dc resistivity and seismic data all together in the search for multiple property images that follow a common structural framework. I show some comparative results incorporating individual and combined data in test and field examples for two-dimensional profiles. The results show that the jointly estimated images can be readily incorporated in an integrated model from where the constituent materials could be more easily discriminated and characterized.
DE: 0520 Data analysis: algorithms and implementation
DE: 0902 Computational methods: seismic
DE: 0903 Computational methods: potential fields (1214)
DE: 0925 Magnetic and electrical methods (5109)
DE: 3260 Inverse theory
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly