Published online by Cambridge University Press: 16 November 2020
The seismic signals from major events continue to propagate through the Earth for hours. The application of correlations between seismic stations to these long codas extracts steeply travelling body waves as the main contributors to the correlation wavefield. The properties of the coda correlation depend on the differences between the seismic phases that are being correlated. As a result, the correlation wavefield of the coda emphasises seismic phases that are difficult to detect in direct excitation by a source and so can provide new information on internal structure, e.g., an improved estimate of the shear wavespeed in the inner core.