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Ministry of Energy Mines and Responsible for Core Review

Earthquake Hazards Mapping of Greater Victoria

To view any of the following maps at full size (in JPG format), click on the small map images.  To download or view in PDF format, you require Adobe Reader™. The PDF files for each of the earthquake hazard maps have been created in a high resolution format to maximize their legibility and are best viewed by downloading and using the zoom functions in Adobe or by generating large-format hard copy output, e.g., E-size plots (36" x 48").

 

Related publications:

 

  • Geoscience Map 2000-1: Relative Earthquake Hazard Map of Greater Victoria, Showing Areas Susceptible to Amplification of Ground Motion, Liquefaction and Earthquake-Induced Slope Instability
  • Geoscience Map 2000-3: Relative Earthquake Hazard maps of Greater Victoria Sheets 3A, 3B, and 3C and Accompanying Report

 

Composite Earthquake Hazard Map

Composite Relative Earthquake Hazard Map of Greater Victoria (Geoscience Map 2000-1): The objective of this map is to show areas of Greater Victoria where the earthquake hazard is likely to be increased due to the presence of potentially unstable slopes, and soils susceptible to amplification of ground motion and/or liquefaction. This map has been compiled from three other maps: a relative liquefaction hazard map, a relative amplification of ground motion hazard map, and an earthquake-induced slope instability hazard map.

Amplification Hazard Map

Relative Amplification of Ground Motion Hazard Map of Greater Victoria (Geoscience Map 2000-3, Sheet 3B):  This map shows areas where the earthquake hazard is increased due to amplification of ground motion.  The amplification of ground motion hazard has been estimated on the basis of the National Earthquake Hazard Reduction Program (NEHRP) site classes for the susceptibility to amplification of ground motion (Building Seismic Safety Council, 1994), which are based on the average response of various types of soils.

 

Liquefaction Hazard Map

Relative Liquefaction Hazard Map of Greater Victoria (Geoscience Map 2000-3, Sheet 3A):  This map shows areas of Greater Victoria in which the earthquake hazard is potentially increased due to the presence of soils susceptible to liquefaction. Liquefaction is the transformation that occurs when earthquake shaking (or other disturbance) causes a saturated granular soil to lose its strength and behave like a liquid and can be one of the major causes of damage during an earthquake. The susceptibility of a site to liquefaction depends on the depth to water table and the density, grain size and age of the underlying deposits. This map was prepared by assigning a hazard rating to each geological map unit based on these criteria and quantitative analyses.

 

Slope Stability Map

 

Seismic Slope Stability Map of Greater Victoria (Geoscience Map 2000-3, Sheet 3C):  Seismic slope hazard mapping is intended to show relative susceptibility to earthquake-induced slope failures.   The seismic slope hazard map is based on a compilation of existing subsurface data, previous slope stability assessments, bedrock geology and surficial geology maps, topographic data, and airphoto interpretation.  Stability analyses were conducted on twelve different slope models including typical or simplified slopes found throughout the Victoria area as well as specific, complex slope models where more detailed information was available.  The stability analyses determined both the static factor of safety and the yield acceleration (the intensity of seismic motions that would cause a slope failure).

Quaternary Geological Map

Quaternary Geological Map of Greater Victoria (Geoscience Map 2000-2):  This map shows the thickness and distribution of the Quaternary stratigraphic units in Greater Victoria.  It is intended to provide the geological basis for the assessment of the earthquake hazards shown on companion maps which depict the liquefaction and amplification of ground motion in Greater Victoria (Geoscience Maps 2000-3a and 2000-3b; Monahan et al., 2000b and c). The geological units shown here are defined in part to reflect these hazards.

 

All publications of the BC Geological Survey are available digitally, free of charge, from this website.

 

For questions or more information on geology and minerals in British Columbia contact BCGS Mailbox or call toll free (B.C. residents only).