Given a certain set of assumptions about the Earth
(i.e. a solution-space), our tomographic inversions can determine images
of the Earth, belonging to that solution-space,
that provide a ``best-fit'' to the available seismic data.
If our assumptions are correct (that is, if the solution-space is adequate),
separate inversions of different datasets, that are sensitive to a certain
feature of the Earth, should lead to consistent images of that feature;
on the contrary, discrepancies between the results of
those independent inversions might indicate
the the solution has not been sought in the appropriate solution-space.
This image includes tomographic models of the laterally varying
CMB topography(in km)
resulting from independent inversions of
several data-subsets (P and PcP, P and PKPbc, P and PKPdf
and all of the above); based upon the above reasoning, the consistency
between CMB-models belonging to the same solution-space but obtained
from different data is a measure of the likelihood of the solution-space
itself. Details on the subsets of data used to obtain each model,
the solution-space where the solution-model was seeked, and
the associated variance reductions, are given in the table below.
isotropic mantle,
anisotropic mantle,
isotropic mantle,
anisotropic mantle,
PREM outer core.
PREM outer core.
heterogeneous outer core.
heterogeneous outer core.
P, PcP
model 1
model 5
same as 1
same as 5
P: 29.3%
P: 29.9%
PcP: 7.6%
PcP: 10.2%
PKPbc: -14.5%
PKPbc: 18.0%
PKPdf: -12.7%
PKPdf: 6.8%
cumulative: 16.3%
cumulative: 23.1%
P, PKPbc
model 2
model 6
model 9
model 12
P: 29.4%
P: 30.3%
P: 28.5%
P: 31.5%
PcP: -17.5%
PcP: -8.4%
PcP: -29.2%
PcP: -19.7%
PKPbc: 40.9%
PKPbc: 43.5%
PKPbc: 50.3%
PKPbc: 53.1%
PKPdf: 14.7%
PKPdf: 15.4%
PKPdf: 11.4%
PKPdf: 12.6%
cumulative: 22.4%
cumulative: 26.6%
cumulative: 20.3%
cumulative: 23.6%
P, PKPdf
model 3
model 7
model 10
model 13
P: 29.5%
P: 32.9%
P: 28.8%
P: 32.0%
PcP: -19.0%
PcP: -11.2%
PcP: -23.1%
PcP: -12.4%
PKPbc: 27.4%
PKPbc: 32.2%
PKPbc: 1.0%
PKPbc: 7.1%
PKPdf: 19.6%
PKPdf: 22.7%
PKPdf: 28.6%
PKPdf: 30.9%
cumulative: 22.7%
cumulative: 26.6%
cumulative: 22.7%
cumulative: 26.6%
All
model 4
model 8
model 11
model 14
P: 29.4%
P: 29.7%
P: 28.8%
P: 29.1%
PcP: 1.6%
PcP: 9.5%
PcP: 4.0%
PcP: 8.2%
PKPbc: 33.9%
PKPbc: 36.5%
PKPbc: 43.9%
PKPbc: 45.0%
PKPdf: 18.5%
PKPdf: 21.1%
PKPdf: 26.6%
PKPdf: 28.0%
cumulative: 24.7%
cumulative: 26.3%
cumulative: 26.5%
cumulative: 27.4%
From "Whole Earth tomography from delay times of P, PcP, PKP phases:
lateral heterogeneities in the outer core, or radial anisotropy
in the mantle?" by myself and A. M. Dziewonski,
J. Geophys. Res., 104, 25,267-25,594, 2000.
THE MODEL 8 IS AVAILABLE VIA ANONYMOUS FTP at
ftp.seismology.harvard.edu.
Once you are connected type ``cd users/boschi/ANISOTROPY'';
the ``read.me'' file in that directory will provide informations as to
the contents of the various files. Email Lapo Boschi for
further questions.
Harvard seismology: 3-D Earth Structure
Lapo Boschi,
Department of Earth and Planetary Science, Harvard University
