Ray-parameter based stacking and enhanced pre-conditioning for stable inversion of receiver function data
Author
Chen, Youlin; Niu, Fenglin
Date
2013Abstract
While inversion of seismic velocity from receiver function data could be instable due to
its intrinsic non-linearity and non-uniqueness, improper stacking of receiver function could
also introduce significant biases to the resulting velocity structure. In a distance section of
receiver functions, the Moho Ps conversion and the two reverberations possess a positive
and negative moveout, respectively. Stacking receiver functions without moveout correction
could significantly reduce and distort the amplitude and waveform of these phases. Inversion
with these incorrectly stacked receiver functions will thus inevitably introduce artefacts to the
resulting velocity structure. In this study, we have improved the inversion procedure in two
ways. First, we introduce a ray-parameter based (RPB) stacking method to correctly construct
receiver function data for inversion. Specifically we develop a ‘four-pin’ method that accounts
for the moveout effect of the converted and reverberated phases in stacking individual receiver
functions recorded at various distances. Secondly, we divide the receiver function trace into
conversion and reverberation windows and assign different weights between the two windows
in the inversion. More weight is given to the Ps conversion window in resolving the shallow
structure, which can be nearly fixed in the successive inversion of deeper structure. We also
employ other pre-conditioning proposed by previous studies, such as balancing the receiver
function data being filtered with different Gaussian filters, smoothing the velocity model and
further regulating the model based on existing information. We compute synthetic receiver
functions at distances between 30◦ and 90◦ from a target model and then use the RPB stacking
method to generate the input data for various inversions (iterative linear) with different initial
models. Our inversions with enhanced pre-conditioning and RPB stacked data demonstrate a
good capability in recovering the target model from generally more stable iterations. Applying
these techniques to two broad-band stations in China indicates that the improvements on data
stacking and inversion can eliminate potential stacking-induced artefacts, and yield models
more consistent with surface geology.
Citation
Published Version
Keyword
Type
Journal article