Optimising resolution and improvement strategies for emerging geodatabases in developing countries

Geotechnical and geological data are needed for the seismic hazard assessments that inform earthquake risk management and resilient engineering design. This paper reviews information typical of that available in developing countries for the definition of the shear wave velocity in the first 30 meters of soil (VS30). This paper aims to determine optimal resolutions for different data sources in relation to the definition of VS30 maps and the identification of an optimal strategy for localisation of new site investigations (i.e., new boreholes). The context of developing countries, being characterised by endemic lack of high-quality archived data and lack of systematic financial sources, makes the scope of the study challenging and different from the geological and geotechnical approaches typically used in developed countries. Within this context, the auxiliary employment of empirical correlations for the evaluation of VS30 is also discussed as a means of defining cost-effective investigation strategies for developing countries. The Kathmandu Basin in Nepal is used as a representative case study. Preliminary data collected within the University of Bristol led project SAFER - Seismic Safety and Resilience of Schools in Nepal - are critically analysed to the aim of identifying (i) the critical resolution for geodatabase layers (e.g., the digital elevation model) and (ii) the best location for new borehole tests aimed at improving the quality of the VS30 model for the Basin. The approach outlined for Nepal is applicable to other seismic prone areas in the developing world.