Effective elastic thickness of the lithosphere is the estimated thickness of the elastic plate to substitute for lithosphere in order to investigate observed deformation.
It is also presented as T
e (effective or equivalent).
Effective elastic thickness of the oceanic lithosphere
T
e is largely dependent on the thermal structure of the
lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...
,
its thickness and the coupling of crust with mantle.
For the
oceanic lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...
with coupled crust and mantle, T
e is usually taken to the base of the mechanical lithosphere (isotherm of 500 - 600 °C). This way it is also age dependent, as gradually thickens moving off the oceanic ridge.
Effective elastic thickness of the continental lithosphere
For the
continental lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years o ...
more aspects are taken under consideration, thermal age is only the estimate for slowly cooling
craton
A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and ...
ic areas, where mantle is involved and T
e reaches large values.
Similar conditions are expected also on terrestrial planets.
If the crust is decoupled from mantle, value follows the average crustal thickness. Topography load is also important factor, significantly lowering the value of T
e.
Methods of determination
Methods for T
e determination on continents are mostly based on thermal and rheological approach, but also on comparison of gravity anomalies and topography.
For thermally young areas Te is about 20-30 km, for older 40-50 km, cratons can reach more than 100 km. Determination of the effective elastic thickness is important for
Earth's surface deformation studies, warp tectonics, glacial isostatic rebound and sea-level changes.
See also
*
Lithospheric flexure
Lithospheric flexure (also called regional isostasy) is the process by which the lithosphere (rigid, thin outer layer of the Earth) bends under the action of forces such as the weight of a growing orogeny or changes in ice thickness related to glac ...
References
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Lithosphere