Earthquake Hazard GIS Modelling in the Greater Vancouver Regional District

Overview

The analysis model of earthquake hazards on Greater Vancouver Regional District (GVRD) was generated based on the theories of the following models:

Victoria Earthquake Hazard mapping by Ministry of Energy Mines

Assessment Of Susceptibility To Soil Liquefaction In Taiwan

Analysis of Soil Borings for Liquefaction Resistance

Liquefaction Hazard and Shaking Amplification Maps of Alameda, and etc.....by USGS

GeoMap Vancouver by Natural Resources Canada

Mapping Ski Hill Avalanche Terrain in the Vancouver, B.C., Area by Earth Observation Magazine

Avalanche by Glacier Valley Education

Three Earthquake Geotechnical hazard factors are summarized from the above models:

• Amplification (due to softness of the surface rocks and thickness of surface sediments. It is greatest in areas underlain by thick deposits of soft clay, particularly where they are capped by peat and organic soils, and lowest where bedrock is exposed.)
• Liquefaction Susceptibility (Liquefaction occurs only in saturated soils. It is greatest in low lying, near water bodies with young age of underlying soil deposits and with coarse soil texture of sand. It is also affected by the depth to water table and the density and grain size of the underlying soil deposits. For more information on liquefaction see Soil Liquefaction Website by University of Washington.)
• Slope Instability(Bedrock instability, Landslide or Avanlanche susceptibility. Most landslides in Vancouver occur on slopes that are steeper than 20 degrees and in sedimentary bedrock. Avanlanche susceptibility is highest on leeward slopes on northeastern-, eastern-, or southeastern-facing slopes because of the southwesterly, westerly and southerly prevailing winds in western Canada.

Another factor (that is not present in the models above) was also added to the list above. It is Earthquake Intensity based on the degree of closeness to nearest fault lines.

The four factors above are mapped individually using various methods in IDRISI32. The four factors are then combined into one single map model that represent the relative earthquake hazard. See Data Section and Methodology for the data and methods used.