Dynamic Component of the Asthenosphere: Lateral Viscosity Variations Due To Dislocation Creep at the Base of Oceanic Plates
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F24%3A10489475" target="_blank" >RIV/00216208:11320/24:10489475 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=yMk7c9Rq7f" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=yMk7c9Rq7f</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1029/2024GL109116" target="_blank" >10.1029/2024GL109116</a>
Alternative languages
Result language
angličtina
Original language name
Dynamic Component of the Asthenosphere: Lateral Viscosity Variations Due To Dislocation Creep at the Base of Oceanic Plates
Original language description
The asthenosphere is commonly defined as an upper mantle zone with low velocities and high attenuation of seismic waves, and high electrical conductivity. These observations are usually explained by the presence of partial melt, or by a sharp contrast in the water content of the upper mantle. Low viscosity asthenosphere is an essential ingredient of functioning plate tectonics. We argue that a substantial component of asthenospheric weakening is dynamic, caused by dislocation creep at the base of tectonic plates. Numerical simulations of subduction show that dynamic weakening scales with the surface velocity both below the subducting and the overriding plate, and that the viscosity decrease reaches up to two orders of magnitude. The resulting scaling law is employed in an apriori estimate of the lateral viscosity variations (LVV) below Earth's oceans. The obtained LVV help in explaining some of the long-standing as well as recent problems in mantle viscosity inversions. The motion of lithospheric plates at the Earth's surface is enabled by a weak underlying layer-the asthenosphere. The origin of this low viscosity layer is still subject of discussion. Presence of water or partial melt were proposed as possible reasons of its reduced viscosity. Another mechanism that may lead to weakening is non-linear deformation. Rheological description of asthenospheric material includes dislocation creep, a deformation mechanism that depends on the velocity contrast between the lithospheric plate and underlying mantle-the faster the plates are, the weaker the underlying layer becomes and vice versa. Here we argue that a substantial component of asthenospheric weakening is dynamic, caused by this deformation mechanism. We evaluate numerical models of subduction including dislocation creep and derive a relation between the surface velocity of oceanic plates and the magnitude of the underlying asthenospheric viscosity. This allows us to estimate how the viscosity varies under different oceanic plates on Earth, which is otherwise hard to constrain. Our results indicate that the asthenosphere below the Pacific plate should be particularly weak. Substantial component of asthenospheric weakening is dynamic, caused by dislocation creep at the base of tectonic plates Dynamic weakening scales with the surface velocity both below the subducting and the overriding plate The resulting scaling law is employed in an apriori estimate of the lateral viscosity variations below Earth's oceans
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10500 - Earth and related environmental sciences
Result continuities
Project
<a href="/en/project/GA23-06345S" target="_blank" >GA23-06345S: Seismo-geodynamic modeling of the Hellenic subduction</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Geophysical Research Letters
ISSN
0094-8276
e-ISSN
1944-8007
Volume of the periodical
51
Issue of the periodical within the volume
13
Country of publishing house
US - UNITED STATES
Number of pages
14
Pages from-to
e2024GL109116
UT code for WoS article
001257309200001
EID of the result in the Scopus database
2-s2.0-85197382076