Preliminary reference Earth model: Difference between revisions

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{{Short description|Model representing the average Earth properties as a function of planetary radius}}

{{more footnotes|date=January 2013}}

[[File:EarthGravityPREM.jpg|thumb|Earth's Gravity according to PREM. Green curves show hypothetical Earths with density constant (dashed) and decreasing linearly from center to surface (stippled)|300x300px]]

==Preliminary Reference Earth Model (PREM) ==

The '''preliminary reference Earth model''' ('''PREM''') plots the average of [[Earth]]'s properties by depth.<ref>{{cite journal|last1=Dziewonski|first1=Adam M.|date=June 1981 |title=Preliminary reference Earth model |journal=Physics of the Earth and Planetary Interiors |volume=25 |issue=4 |pages=297–356 |url=https://www.cfa.harvard.edu/~lzeng/papers/PREM.pdf|doi=10.1016/0031-9201(81)90046-7 |last2=Anderson |first2=Don L. |bibcode=1981PEPI...25..297D}}</ref> It includes a table of Earth properties, including [[elasticity (physics)|elastic]] properties, [[Anelastic attenuation factor|attenuation]], [[density]], [[pressure]], and [[Gravity of Earth|gravity]].

The Preliminary Reference Earth Model is a 1-D model representing the average [[Earth]] properties as a function of planetary radius. PREM was developed in response to guidelines of a "Standard Earth Model Committee" of the

International Association of Geodesy (IAG) and the International Association of Seismology and Physics of the Earth's Interior (IASPEI).

PREM has been widely used as the basis for [[seismic tomography]] and related global [[geophysics|geophysical]] models.<ref>{{cite PREMbook|last1=Dziewonski |first1=A. M. |last2=Romanowicz |first2=B.A. |title=1.01 - Overview|journal= Treatise on Geophysics |editor-first=Gerald |editor-last=Schubert |date=2007 |pages=1–29 |isbn=9780444527486 |doi=10.1016/B978-044452748-6.00001-8|bibcode=2007sse..book....1D }}</ref> It incorporates [[Anelasticity|anelastic]] dispersion and [[seismic anisotropy|anisotropy]] and therefore it is frequency-dependent and transversely [[Isotropy|isotropic]] for the [[Mantleupper mantle (geologyEarth)|upper mantle]].

PREM was developed by [[Adam Dziewonski|Adam M. Dziewonski]] and [[Don L. Anderson]] in response to guidelines of a "Standard Earth Model Committee" of the [[International Association of Geodesy]] (IAG) and the [[International Association of Seismology and Physics of the Earth’s Interior|International Association of Seismology and Physics of the Earth's Interior]] (IASPEI) Other Earth reference models include iasp91<ref>{{Cite book|title=IASPEI 1991 Seismological Tables|last=Kennett|first=B.L.N.|publisher=Bibliotech|year=1991|___location=Canberra, Australia}}</ref> and ak135.<ref>{{Cite journal|last1=Kennett|first1=B. L. N. |last2=Engdahl |first2=E. R. |last3=Buland |first3=R. |date=1995-07-01 |title=Constraints on seismic velocities in the Earth from traveltimes |journal=Geophysical Journal International |volume=122 |issue=1 |pages=108–124 |doi=10.1111/j.1365-246X.1995.tb03540.x |issn=1365-246X |bibcode=1995GeoJI.122..108K|doi-access=free }}</ref>

PREM includes a table of Earth properties, including elastic properties, Q, [[density]], [[pressure]], and [[Gravity of Earth|gravity]], as a function of planetary radius.

PREM was developed by [[Adam Dziewonski|Adam M. Dziewonski]] and [[Don L. Anderson]].

Other Earth Reference Models include IASPE91.

==References==

{{Reflist}}

*Dziewonski, A.M., and D.L. Anderson. 1981. "Preliminary reference Earth model." Phys. Earth Plan. Int. '''25''':297-356.

==External links==

*[http://wwwds.iris.edu/dmsds/products/emc-prem/models/PREM.htm IRIS EMC - Reference Earth Models]

*[http://geophysicsds.ouiris.edu/solid_earthfiles/premproducts/emc/data/GYPSUM/StartingVpModel_PREM.htmltxt Table of values in PREM model]

* [http://www.typnet.net/Essays/EarthGrav.htm Model formulas, inputs, and overview]

[[Category:Structure of the Earth]]