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| Titel |
Applying local Green's functions to study the influence of the crustal structure on hydrological loading displacements |
| VerfasserIn |
Robert Dill, Volker Klemann |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102129
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| Publikation (Nr.) |
 EGU/EGU2015-1408.pdf |
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| Zusammenfassung |
| The influence of the elastic Earth properties on seasonal or shorter periodic surface mass
loads due to atmospheric surface pressure and terrestrial water storage variations is usually
modeled by applying a local isostatic model like a homogeneous half-space model, or by a
one dimensional spherical Earth model like PREM from which a unique set of elastic load
Love numbers, or alternatively, elastic Green’s functions are derived. The drawbacks of these
strategies are that, in the first case, the response according to the local Earth structure is
valid only if load and observer almost coincide, or that, in the second case, only the
response of an average Earth structure is considered. However, for surface loads
with horizontal scales less than 2500 km2, as for instance, for strong localized
hydrological signals associated with heavy precipitation events and river floods, the Earth
elastic response becomes very sensitive to inhomogeneities in the Earth crustal
structure.
We derive a set of local Green’s functions defined for every global 1°x 1° gridcell for
the 3-layer crustal structure TEA12. Local Green’s functions show standard deviations of
±12% in the vertical and ±21% in the horizontal directions for distances in the
range from 0.1° to 0.5°. The application of local Green’s functions introduces a
variability of 0.5 - 1.0Âmm into the hydrological loading displacements, both in
vertical and in horizontal directions. Maximum changes due to the local crustal
structures are from -25% to +26% in the vertical and -91% to +55% in the horizontal
displacements. In addition, the horizontal displacement changes its direction significantly,
even to the opposite. The modeling of a site-dependent crustal response to surface
loads provides an alternative way to probe the density and elastic structure of the
Earth’s crust and mantle by means of observed surface deformations caused by mass
re-distributions. In addition, realistic loading models allow the monitoring of mass
variations of the hydrosphere and cryosphere in the spatial range between satellite
resolution and in-situ observations by the analysis of geodetically measured surface
displacements. |
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