Accession Number:

AD0652500

Title:

1966 LAKE SUPERIOR SEISMIC EXPERIMENT - ONTARIO-QUEBEC REFRACTION PROFILES

Descriptive Note:

Final scientific rept.

Corporate Author:

STANFORD RESEARCH INST MENLO PARK CA

Report Date:

1967-04-01

Pagination or Media Count:

41.0

Abstract:

As a part of EARLY RISE, a project designed to investigate the crustal structure of the central portion of the North American continent, researchers recorded the first arrival times and signal amplitudes of refracted compressional waves from 38 chemical explosions detonated in July of 1966 on the floor of Lake Superior. Refraction seismic data were obtained along traverse from Chapleau, Ontario, to Schefferville, Quebec, SRI traverse, and from Chapleau, Ontario, to Chibougamau, Quebec, to Glace Bay, Nova Scotia Geotech traverses. From these measurements, the following tentative conclusions are reached The upper mantle velocity determined from a least squares fit to the overall SRI and Geotech first arrival data is 8.50 plus or minus 0.01 kmsec. This velocity is considerably higher than that observed in other northern regions, notably upper Michigan, central Minnesota and north-central Wisconsin. The constancy of the upper mantle velocity suggests that the regional dip of the upper mantle--crust boundary is near zero and that the thickness of the curst is uniform. Employing the value of the crustal velocity based on the 1963 Lake Superior experiment data, it was estimated that crust in this region is quite thick, the upper mantle-crust boundary lying at a depth of approximately 60 km.

Subject Categories:

  • Geology, Geochemistry and Mineralogy
  • Seismology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE