TECTONIC FEATURES OF THE EARTH'S CRUST AND UPPER MANTLE.
Final technical rept.,
PITTSBURGH UNIV PA DEPT OF EARTH AND PLANETARY SCIENCES
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The report deals primarily with a study of Rayleigh surface waves crossing the continent of North America. From this study, a Rayleigh wave phase velocity map was constructed. Features prominent on this map are the following a large region of high velocities under the Canadian Shield, a prominent low velocity region generally under the Basin and Range province of the western United States moving towards the east as the period shortens from 51 to 20 seconds, a sharp gradient in phase velocity as one traverses the Northern Rocky Mountain region, an isolated region of higher velocities at the southern end of the Appalachian mountains at 51 and 40 seconds period, a region of lower velocities migrating from west of the St. Lawrence River at a period of 51 seconds, to under the Ohio, Indiana, Kentucky region at a period of 20 seconds, generally higher values of phase velocity on the east coast of North America compared to the west coast. A subsidiary investigation revealed the scattering of long period seismic energy by the velocity gradient under the Rocky Mountains. Author
- Radiofrequency Wave Propagation