Open AccessInversion for laterally heterogeneous upper mantle S‐wave velocity structure using iterative waveform inversion
Author(s) -
Hara Tatsuhiko,
Tsuboi Seiji,
Geller Robert J.
Publication year - 1993
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1993.tb01487.x
Subject(s) - seismogram , geology , inversion (geology) , spherical harmonics , geodesy , waveform , wavelength , perturbation (astronomy) , iterative method , geophysics , seismology , mathematical analysis , mathematics , algorithm , physics , optics , quantum mechanics , voltage , tectonics
In contrast to previous work, which treats the Earth's lateral heterogeneity as an infinitesimal perturbation to a spherically symmetrical starting model, we conduct iterative linearized waveform inversion for the Earth's laterally heterogeneous structure. We use the Direct Solution Method (DSM) (Geller et al. 1990a) to calculate synthetic seismograms and their partial derivatives for a laterally heterogeneous earth model. We invert surface‐wave data from the IDA and GEOSCOPE networks. We expand the lateral heterogeneity of rigidity in spherical harmonics up to angular order number 8 and use three parameters to specify the depth dependence of each harmonic, giving us a total of 240 unknowns. The short‐wavelength lateral heterogeneity (s = 4, 6 and 8) in the deeper part of the upper mantle obtained by this study differs significantly from M84A. The relative improvement in the variance reduction as compared with model M84A is about 20 per cent for the IDA data and more than 100 per cent for the GEOSCOPE data.