Example of a scientific result from a major seismology field depolyment

Mantle structure beneath the TransAntarctic Mountains

The structure of the deep Earth, far deeper than it is possible to drill, can only be determined by indirect methods. Seismology is one example of a geophysical method that allows us to investigate the deep Earth. Seismic waves travel faster or slower depending on the composition and temperatures of the rock through which the waves are travelling. This allows seismologists to build up a tomographic image of the Earth beneath seismic recording stations in a similar (though bigger scale!) process to the way that medical scans provide images of the human brain.

Seismic stations were deployed across the TransAntarctic mountains to record the energy from distant, teleseismic earthquakes. Combining data from all the stations allows images to be built showing variations in the seismic structure of the deep earth. Seismic waves travel slower in warmer mantle.

The picture below shows variations in seismic velocity across the TransAntarctic Mountains (TAM) at the boundary between East Antarctica (Wilkes Basin) and West Antarctica (Ross Sea Coast). The crust becomes shallower under the Ross Sea (black line) and the warm mantle (light blue colours) extends beneath the mountains.

Cross section through the Transantarctic Mountains (TAM) shear velocity model. Warm upper-mantle from the Ross Sea extends beneath the TAM (Lawrence et al., 2006).

Lawrence, J.F., and D.A. Wiens, A.A. Nyblade, S. Anandakrishnan, P.J. Shore, D. Voigt, Comprehensive seismic and geophysical study of the Transantarctic Mountains, East Antarctica, and the West Antarctic Rift System, G³, in review, 2006.