The main objective of this research is to compare the risk assessment methods among RADIUS, GESI, and seismic microzonation (JICA 2002) focusing on entire Kathamandu Metropolitan City. The process of conducting the risk assessment is based on a review of the technical features of hazards and their location, intensity, frequency and probability and also the analysis of physical, socio-economic and environment dimensions of vulnerability.
The methods mentioned above are used to estimate the seismic hazard for developing countries like Nepal. In particular, the RADIUS and GESI methods require much less cost and time, which are very important in terms of economy. Seismic microzonation (JICA2002), on the other hand, requires a more detailed treatment and consumes more time.
The results obtained by three methods were compared to each other. As to building damage, similar results were obtained by the three methods. However, as for causalities, RADIUS and GESI give the lower values than the results obtained by the seismic microzonation (JICA2002). This would be due to the fact that the seismic microzonation by JICA (2002) adopted empirical relation between of building damage and death toll based on the damage caused by 1934 Bihar-Nepal Earthquake and the 1988 Udayapur Earthquake. If the situation would be reflected appropriately, the value would be approach to RADIUS and GESI. Thus it can be concluded that RADIUS and GESI are practical and useful for developing country. It is recommended to use RADIUS and GESI as the first approach for seismic risk assessment.