Free oscillations of a spherical anelastic earth

Jeroen Tromp, F. A. Dahlen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


We show how to calculate exact complex eigenfrequencies and eigenfunctions and exact single mode synthetic seismograms for a spherical anelastic earth model. The real frequencies of oscillation of some spheroidal modes differ by 1 to 2 μHz from the corresponding spherical elastic earth eigenfrequencies. The decay rates are generally well approximated by conventional first‐order perturbation theory. The complex radial eigenfunctions of the most strongly affected modes differ substantially from the corresponding real elastic eigenfunctions, and this can lead to significant perturbations in the initial phase and amplitude of the associated free oscillations following an earthquake. Most, but not all, of the strongly affected modes have large displacements in the inner core.

Original languageEnglish (US)
Pages (from-to)707-723
Number of pages17
JournalGeophysical Journal International
Issue number3
StatePublished - Dec 1990

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology


  • anelasticity
  • free oscillations
  • normal modes
  • spherical earth.


Dive into the research topics of 'Free oscillations of a spherical anelastic earth'. Together they form a unique fingerprint.

Cite this