The banana doughnut theory - also sometimes known as Born-Fréchet kernel theory, or finite-frequency theory - is a model in

seismic tomography Seismic tomography or seismotomography is a technique for imaging the subsurface of the Earth using seismic waves. The properties of seismic waves are modified by the material through which they travel. By comparing the differences in seismic waves ...

that describes the shape of the

Fresnel zone A Fresnel zone ( ), named after physicist Augustin-Jean Fresnel, is one of a series of confocal prolate ellipsoidal regions of space between and around a transmitter and a receiver. The size of the calculated Fresnel zone at any particular di ...

along the entire ray path of a body wave. 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. The name was coined by Princeton University postdoc Henk Marquering. This theory gets the name "

banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large treelike herbaceous flowering plants in the genus '' Musa''. In some countries, cooking bananas are called plantains, distinguishing the ...

" because the tube of influence along the entire ray path from source to receiver is an arc resembling the fruit. The "

doughnut A doughnut or donut () is a type of pastry made from leavened fried dough. It is popular in many countries and is prepared in various forms as a sweet snack that can be homemade or purchased in bakeries, supermarkets, food stalls, and fran ...

" 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. Mohammad Youssof and colleagues (Youssof et al., 2015) of Rice University and the University of Copenhagen conducted one of the studies that compared both the Born-Fréchet kernel theory and the infinitesimal geometrical ray theory when they used the same datasets to see the resolving power on real datasets from the South African Seismic Array ASEin Kalahari (Carlson et al., 1996) and compared their results when using one and multiple frequencies to previous studies by Fouch et al. (2004), Priestley et al. (2006), and Silver et al. (2001). Youssof et al. (2015) models are similar in some ways, but they also have significant differences which include new results of cratonic boundaries, the keels' depth, and their structures.

References

Seismology measurement {{Seismology-stub