THREE-DIMENSIONAL EMPIRICAL TRAVELTIMES: CONSTRUCTION AND APPLICATIONS

Abstract

A new approach for predicting traveltimes is proposed which makes use of sophisticated smoothing and interpolation techniques applied to observations from large earthquake catalogues. The technique produces 3-D empirical traveltimes directly from a database of observations and does not impose any arbitrary spatial scalelength on the data, for example by smoothing observations over a pre-determined distance interval. This feature allows the spatial variability in data density, as well as multiple length scales of heterogeneity, to be handled in a natural way. After removing the empirical traveltimes from observed traveltimes, the remaining residuals are spatially uncorrelated and, in this sense, all of the heterogeneity signal in the data is accounted for.