On Seismic Waves (Fourth Paper)

Abstract

This paper is in continuation of a series under the same title 1) 2) 3). For convenience, these will be referred to in the text as "Seismic Waves I, II, III". These papers were based almost exclusively on the data of shocks at normal depth. It appeared probable that the use of observations of deep-focus earthquakes would lead to more precise determination of travel times, and of the velocities of seismic waves in the interior of the earth. We owe this opportunity to the exceptional sharpness of the recorded impulses from most such shocks, and to the freedom of the seismograms from disturbance by surface waves. The occurrence of such sharp seismograms was pointed out by Zoeppritz in a paper published posthumously in 1912.