Seismic Refraction Surveys in British Columbia, 1941–1966– a Preliminary Interpretation

  1. Leon Knopoff,
  2. Charles L. Drake and
  3. Pembroke J. Hart
  1. W. R. H. White,
  2. M. N. Bone and
  3. W. G. Milne

Published Online: 18 MAR 2013

DOI: 10.1029/GM012p0081

The Crust and Upper Mantle of the Pacific Area

The Crust and Upper Mantle of the Pacific Area

How to Cite

White, W. R. H., Bone, M. N. and Milne, W. G. (2012) Seismic Refraction Surveys in British Columbia, 1941–1966– a Preliminary Interpretation, in The Crust and Upper Mantle of the Pacific Area (eds L. Knopoff, C. L. Drake and P. J. Hart), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM012p0081

Author Information

  1. Dominion Astrophysical Observatory, Victoria, British Columbia, Canada

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 20 APR 2012

Book Series:

  1. Geophysical Monograph Series

Book Series Editors:

  1. Waldo E. Smith

ISBN Information

Print ISBN: 9780875900124

Online ISBN: 9781118663738

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Keywords:

  • Crustal models and intermediate layer;
  • Gravity and magnetic variation observations;
  • Greenbush Lake to Victoria;
  • Jack of Clubs Lake South-Southeast to Osoyoos;
  • Merritt North-Northwest to Puntchesakut;
  • Puntchesakut Lake South-Southeast to Merritt;
  • Refraction profiles and Ripple Rock;
  • Seismic refraction surveys and Bouguer anomalies

Summary

Seismic refraction studies between 1964 and 1966 in the interior plateau and ranges of British Columbia are described. A reversed profile along the interior plateau from Quesnel to Merritt with an unreversed extension to the U.S. border has been interpreted in two ways. The preferred solution in terms of rms fit shows that the transition from subnormal to normal Pn velocity takes place north of Clinton. The mantle-crust boundary undulates several kilometers, and the crust is on the average 30 km thick. There is no evidence for an intermediate layer, and the upper basement velocity is uniform at 6.1 km/sec. Observations from the Ripple Rock explosion of 1958 and another profile southwest from Revelstoke are difficult to reconcile, since they require a rapid crustal thinning between Kamloops and Hope, B.C., where the inferred depth is only 28 km. A second solution suggests a uniform Pn velocity of 8.0 km/sec and crustal thinning toward the north in the interior plateau and to the west across the interior ranges and plateau. Crustal depths vary from 34 to 28 km in the area. The fit to the observations with this model is not quite so good, but observation parallel and perpendicular to the physiographic strike can be reconcile with gentler dips. Again no intermediate layer velocity can be determined. Neither seismic model fits a naïve interpretation of the gravity data available, and the magnetic variation results are insufficient to help distinguish between them. The uniformly thin crust and the negative Bouguer anomalies suggest that the upper mantle low velocity layer must be at shallow depth in central British Columbia.