The reflected waves from deep focus earthquakes

Source abstract

Abstract The effect of an abnormally deep focus on the reflected waves of earthquakes is considered. In general a number of supplementary reflected waves may occur and if the focus is sufficiently deep, they should produce definite separate phases on the records. The times of travel of both the supplementary waves and the more normal waves have been derived for several depths of focus, C. G. Knott’s paths of longitudinal and transverse waves being taken as a basis. It is found that the commencements of the additional phases can generally be recognised on the seismograms and that the times of transit are in reasonable agreement with the calculated times. This, it is considered, is definite con­firmation of the occurrence of deep focus earthquakes. Further, the appear­ance of the supplementary reflected waves provides a means of recognising a deep focus earthquake from the records of a single station.