Seismic Microzonation Assessment in Hong Kong

This paper describes a comprehensive investigation on the potential seismic site response effects for the ground conditions in Hong Kong. The ground conditions in the North-west New Territories region of Hong Kong have been selected for this investigation and the results are formulated into seismic microzonation maps. Published geological maps and detailed ground investigation information from over 3000 boreholes have been used for the microzonation assessment. The site classification for microzonation is based on the site classification system developed in the United States and China, with modifications to suit Hong Kong's ground conditions. One-dimensional site response analyses have been carried out to establish how various types of site profiles, representative of Hong Kong subsoil conditions in the study area, will potentially respond to earthquake ground motion. The soil properties are determined based on field and laboratory dynamic tests. The response of a suite of soil profiles was investigated using three input earthquake ground-motion levels corresponding to rock motion having a 63%, a 10% and a 2% chance of being exceeded in the next 50 years. The results are presented in terms of defining site classes and deriving surface response spectra for each of these site classes