Geotechnical Hazard Assessment in a Geothermal Environment

The paper describes a methodology which has been used for geotechnical hazard assessment in the planning for a geothermal power development in Indonesia. The most valued output from a hazard assessment is a reliable Hazard Map which can be used by planners and project managers to at least qualitatively recognise areas which could pose a significant geotechnical hazard during project development. In order to prepare a Hazard Map it is first necessary to identify and quantify the relative effects of a large number of site specific and regional variables, for example seismicity, slope angle, drainage, geology and land-use. The proposed methodology identifies three generic hazard attributes termed Regional, State of Nature and Mass Movement. Each of these attributes is subdivided into individual hazard factors which are assigned a qualitative rating and weighting coefficient based on an assessment of its potential to contribute to ground failure. The Hazard Map is the result of the cumulative rating for each individual land unit (grid or slope facet).