Joint inversion of receiver functions, surface wave dispersion and magnetotelluric data
Moorkamp, M., A.G. Jones, and S. Fishwick
We present joint inversion of magnetotelluric, receiver function and Raleigh wave dispersion data
for a one-dimensional Earth using a multi-objective genetic algorithm (GA).
The chosen GA produces not only a family of models that fit the datasets, but also the trade-off between
fitting the different datasets.
The analysis of this trade-off gives insight into the compatibility between the seismic datasets and
the magnetotelluric data and also the appropriate noise level to assume for the seismic data.
This additional information helps to assess the validity of the joint model, and we demonstrate the
use of our approach with synthetic data under realistic conditions.
We apply our method to one site from the Slave Craton and one site from the Kaapvaal Craton.
For the Slave Craton we obtain similar results to our previously published models from joint inversion of
receiver functions and magnetotelluric data, but with improved resolution and control on absolute
velocities. We find a conductive layer at the bottom of the crust, just above the Moho, a low-velocity,
low-resistivity zone in the lithospheric mantle, previously termed the Central Slave Mantle Conductor,
and indications of the lithosphere-asthenosphere boundary in terms of a decrease in seismic
velocity and resistivity.
For the Kaapvaal Craton both the seismic and the MT data are of lesser quality
which prevents as detailed and robust an interpretation, nevertheless we find an indication of a
low-velocity, low-resistivity zone in the mantle lithosphere.
These two examples demonstrate the potential of joint inversion, particularly in combination with non-linear
Journal of Geophysical Research - Solid Earth, 115, B04318, doi:10.1029/2009JB006369..
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Alan G Jones / 30 April 2010 /