Susceptibility modelling of seismically induced effects (landslides and rock falls) integrated to rapid scoring procedures for bridges using GIS tools for the Lowlands of the Saint-Lawrence Valley

Abstract

Assessment of the seismic vulnerability of a bridge structure relies on its structural characteristics and site data. However, seismically induced effects, such as landslides or rock falls, are often unknown at a bridge site, making seismic risk assessment difficult. The objective of this paper is to develop a methodology to produce susceptibility map for landslides and rock falls for the Lowlands of the Saint-Lawrence Valley based on geological and slope models, groundwater table and proximity to watercourses. The methodology is inspired by the concepts of the methodology of Hazus and adapted to the specificity of the region of study. The final map of susceptibility to landslides shows a predominance of high level of susceptibility. The digital inventory of landslides is compared to the landslides susceptibility levels. Sixty-eight percentage (68%) of landslides from the inventory are located on areas evaluated as highly or very highly susceptible. Therefore, the method of attribution of susceptibility level is well correlated to the inventory of landslides. This map is used within scoring procedures for a rapid assessment of the seismic vulnerability of bridges giving a better classification of the most vulnerable installations, improving the effectiveness of mitigation measures and the efficiency of emergency planning.

Keywords

• Site effects
• geographic information systems
• earthquakes
• landslides