TRAVEL TIMES OF PKP FROM PACIFIC EARTHQUAKES

About 3000 PKP readings, as recorded in the International Seismological Summary from 35 earthquakes, have been studied. These provide new evidence that for the Pacific region the J‐B times for the DEF branch of PKP between 110° and 133° need a correction of between ‐1.0 s and ‐1.5s, for 145° < Δ < 147° between 0.0s and 0.5s and at all other distances between 0.0s and ‐1.0s. The AB branch of PKP of the J‐B times needs a decrease of less than 2s for 172° < Δ < 180°, and between 2s and 3s at most other distances. There exists an intermediate branch (GH) like that of Bolt (1962), the times for which are given by the equation where This intermediate branch extends from 130° to 153°, and the possibility of its extending further than 153° is not ruled out. Four different possible positions of the BC branch have been considered. Copyright © 1968, Wiley Blackwell. All rights reserved