220 research outputs found
Maximum-likelihood estimation of lithospheric flexural rigidity, initial-loading fraction, and load correlation, under isotropy
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 fac- tors,
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 frac- tion 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.Comment: 41 pages, 13 figures, accepted for publication by Geophysical Journal
Internationa
Numerical modelling study on the flexural uplift of the Transantarctic Mountains
In this study, based on a 2-D thermomechanical finite element model, the uplift of the Transantarctic Mountains (TAM) is discussed in relation to the flexural uplift of a rheologically layered lithosphere, which is described by Vening-Meinesz's cantilever kinematics. The general model behaviour shows that the thickness of the crust and the geothermal gradient in the lithosphere are the principal factors in controlling the effective elastic thickness (
Сверхлегкие генераторные модули для КВЧ-терапии
Разработаны миниатюрные генераторные модули для КВЧ-терапии, лег-ко фиксируемые в любом месте тела пациента. Могут быть использованы не только в медицине
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