Banana Doughnut theory

The Banana Doughnut theory is a model in Seismic tomography that describes the shape of the Fresnel zone along the entire ray path. This theory suggests that the area that influences the ray velocity is the surrounding material and not the infinitesimally small ray path. This surrounding material forms a tube enclosing the ray but does not incorporate the ray path itself.

This theory gets the name "banana" because tube of influence along the entire ray path from source to receiver is an arc resembling the fruit. The "doughnut" part of the name comes from the ring shape of the cross-section. The ray path is a hollow banana, or a banana-shaped doughnut. An image can be found here: [http://geoweb.princeton.edu/people/faculty/nolet/marqueringb.jpg]

This theory is sometimes known as "Born-Fréchet kernel theory".

Sources

* [http://quake.mit.edu/hilstgroup/robspage/PapersPDF/2005GJI_HH_BDK.pdf] van der Hilst, R. D., and de Hoop, M. V., 2005, Banana-doughnut kernels and mantle tomography, Geophy. J. Int., 163, 956-961, doi:10.1111/j.1365-246X.2005.02817.x