Spatial analysis of shallow slope instability incorporating an engineering geological ground model

Within a GIS (geographical information system), spatial analysis techniques can be used to apply deterministic methods for identifying and mapping areas susceptible to shallow submarine mass movements. This paper describes such a method which allows spatially widespread, rapid, repeatable and cost-effective evaluation of shallow submarine slope risk. A deterministic approach has the advantage of providing a quantitative output; useful in subsequent project risk assessment. The use of GIS in this way is well established. Many of the method limitations described in the literature can now be overcome. This paper describes some advances through which these limitations are being addressed, and the compromises that still need to be made. The paper places emphasis on GIS modeling of the full three-dimensional variation of geotechnical input parameters. This approach allows the type of sophisticated ground model now becoming available from regional engineering geological and geohazard studies to be harnessed and exploited. The approach described in the paper has been applied on deepwater oil and gas projects having development areas of over 1,000 square kilometers.