Seismic Travel-Time Residuals and Plates

Abstract

The existence of residuals of 3 s or more relative to standard travel-time tables is frequently observed between certain seismic sources and observing stations. The cause of these residuals is indeterminate as one can construct both sub-source and sub-receiver structure which explain the observations equally well. For sources in some parts of the world, however, plate tectonics postulates a definite sub-source structure. In the light of this we have examined a few relevant cases and conclude that not only is the residual pattern explained by plates but further information about the nature of the plates is accessible, in particular, the angles of dip and strike. Some other unresolved problems of observational seismology seem amenable to solution by the use of plate structure.