Fréchet kernels for finite-frequency traveltimes-I. Theory
Journal
Geophysical Journal International
Journal Volume
141
Journal Issue
1
Date Issued
2000-01-01
Author(s)
Abstract
We use body wave ray theory in conjunction with the Born approximation to compute 3-D Fréchet kernels for finite-frequency seismic traveltimes, measured by cross-correlation of a broad-band waveform with a spherical earth synthetic seismogram. Destructive interference among adjacent frequencies in the broad-band pulse renders a cross-correlation traveltime measurement sensitive only to the wave speed in a hollow banana-shaped region surrounding the unperturbed geometrical ray. The Fréchet kernel expressing this sensitivity is expressed as a double sum over all forwardpropagating body waves from the source and backward-propagating body waves from the receiver to every single scatterer in the vicinity of this central ray. The kernel for a differential traveltime, measured by cross-correlation of two phases at the same receiver, is simply the difference of the respective single-phase kernels. In the paraxial approximation, an absolute or differential traveltime kernel can be computed extremely economically by implementing a single kinematic and dynamic ray trace along each source-to-receiver ray. © 2000 RAS.
Subjects
Body waves | Fréchet derivatives | Global seismology | Ray theory | Tomography, traveltime
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
141-1-157.pdf
Size
405.1 KB
Format
Adobe PDF
Checksum
(MD5):246a2a8dcb7b8121cf80bcbc69cdaab8