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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

ANALYSIS OF THE EARTHQUAKES ASSOCIATED WITH THE 1965 HOPE LANDSLIDE AND THEIR EFFECTS ON SLOPE STABILITY AT THE SITE

Two small earthquakes (M 3.2 and 3.1) associated with the Hope Slide of January 9, 1965, Canada's largest known historical landslide, have been reanalyzed using original seismograph records. The earthquakes were nearly identical events having similar epicentres, focal depths, magnitudes, and mechanisms and occurred no more than 30 km from the slide site. The revised epicentre calculated for both earthquakes was 49.36 deg N, 121.14 deg W with an uncertainty of about plus or minus 20 km. The new epicentre should be used in preference to the epicentres given for these events in the 1965 Canadian Earthquakes Catalogue and the 1965 International Seismological Centre Bulletin, which are both based on analysis of separate parts of the complete data set. The effect of the seismic accelerations on slope stability was considered and showed that a seismic trigger of the slide was feasible for either earthquake if it had a shallow focal depth and was located no more than about 10 km from the site, but the validity of a seismic trigger could not be confirmed because of the poor quality of the earthquake location. Local observations on the day of the slide show that the slide did not occur at the time of the first earthquake at 03:56 PST but that it may have occurred during the second earthquake at 06:58 PST. The slide mass was strongly shaken by other earthquakes in the region in 1872, 1946, and 1949 and must have had significantly more shear strength at those times than it did in 1965. The prime factor leading to the 1965 Hope Slide thus appears to have been a loss of shear strength in the slide mass sometime after 1949 putting the mass in a state of near-limiting equilibrium by January, 1965.

  • Corporate Authors:

    National Research Council of Canada

    Research Journals
    Ottawa, Ontario K1A 0R6,   Canada 
  • Authors:
    • Wetmiller, R J
    • EVANS, S G
  • Publication Date: 1989-8

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 484-490
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00488250
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 30 1989 12:00AM