SEISMOLOGICAL EVIDENCE PERTAINING TO THE STRUCTURE OF THE EARTH'S UPPER MANTLE
MICHIGAN UNIV ANN ARBOR
Pagination or Media Count:
variation of the velocity of P and S waves with depth in the upper mantle of the earth, and the effect of this variation upon the recorded earth motion at distances less than 3000 km from the source are studied. Body-wave and surface-wave study results of many authorities are examined, and the following conclusions presented 1 there are significant regional variations of velocity in the upper mantle, 2 there is no pronounced shadow zone for P waves resulting from a low-velocity channel in the upper mantle, except in tectonically active regions such as California-Nevada, Japan, Andes, etc., and 3 there is a significant, world-wide low-velocity channel for S waves. A tabulated summary of upper mantle structure according to geographical region is presented. A summary, recommended problems for future research, and a statement of instrumentation requirements for further study of the upper mantle complete the presentation.
- Geology, Geochemistry and Mineralogy