Dear colleagues, if someone can answer me, may a Geophysicists who are familiar with both, elastic seismic inversion and effective elastic thickness (EET) estimation from gravity data.
Introduction:
An elastic material such as the Earth´s interior is defined by Vp, Vs, and density.
Density is one of the most important properties influencing the sedimentary basins: Lateral density variations drive mass transport on all scales, from plate tectonics (e.g. Forsyth & Uyeda 1975; Chapple & Tullis 1977; Bunge et al. 2003; Liu & Gurnis 2008; Warners-Ruckstuhl et al. 2012), mantle convection (Turcotte & Schubert 2014) and oil and gas reservoir in sedimentary basins by quantitative seismic, e.g., structure, stratigraphy, velocity, density, porosity (Zhang and McMillan, 2018).
Question:
How is the relationship that may exist between flexural rigidity/density derived from gravity, and elastic parameters derived from seismic prestack elastic inversion? How could constrain the answers?
Best regards, Mario E. Sigismondi
Dear Mario Emilio Sigismondi sir,
Topography and gravity are geophysical fields whose joint statistical structure derives from interface-loading processes modulated by the underlying mechanics of isostatic and flexural compensation in the shallow lithosphere. Under this dual statistical-mechanistic viewpoint an estimation problem can be formulated where the knowns are topography and gravity and the principal unknown the elastic flexural rigidity of the lithosphere. In the guise of an equivalent ‘effective elastic thickness’, this important, geographically varying, structural parameter has been the subject of many interpretative studies, but precisely how well it is known or how best it can be found from the data, abundant nonetheless, has remained contentious and unresolved throughout the last few decades of dedicated study. The popular methods whereby admittance or coherence, both spectral measures of the relation between gravity and topography, are inverted for the flexural rigidity, have revealed themselves to have insufficient power to independently constrain both it and the additional unknown initial-loading fraction and load-correlation factors, respectively. Solving this extremely ill-posed inversion problem leads to non-uniqueness and is further complicated by practical considerations such as the choice of regularizing data tapers to render the analysis sufficiently selective both in the spatial and spectral domains. Here, we rewrite the problem in a form amenable to maximum-likelihood estimation theory, which we show yields unbiased, minimum-variance estimates of flexural rigidity, initial-loading fraction and load correlation, each of those separably resolved with little a posteriori correlation between their estimates. We are also able to separately characterize the isotropic spectral shape of the initial-loading processes. Our procedure is well-posed and computationally tractable for the two-interface case. The resulting algorithm is validated by extensive simulations whose behaviour is well matched by an analytical theory with numerous tests for its applicability to real.
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Best regards,
Neeraj Meena,
Thank you...
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