Open AccessSurface waves and free oscillations in a regionalized earth model
Author(s) -
Woodhouse J. H.,
Girnius T. P.
Publication year - 1982
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1982.tb04921.x
Subject(s) - centroid , geology , waveform , modal , geophysics , mathematical analysis , physics , geodesy , statistical physics , mathematics , geometry , quantum mechanics , chemistry , voltage , polymer chemistry
Summary. The linearized equation is derived which relates observed long‐period seismic waveforms to the aspherical perturbations of a spherically symmetric earth model. This is accomplished by formulating the theory of spectral splitting in the time domain. It is shown to be possible greatly to simplify the resulting equations in a way which makes it apparent that for each modal multiplet the ‘scattered’ field depends only upon three local functional of earth structure. The effect of regional structural variations may then be quantified in a manner analogous to that assumed in the ‘pure path technique’, but without making the usual asymptotic approximations. These results are used to investigate the validity of the asymptotic result for the locations of the centroids of spectral peaks in individual recordings, for a regionalized model of the Earth. A technique is suggested for retrieving information about geographical structural variations from low‐frequency waveform data.