Seismic Hazard Analyses of Northern Metropolis and Kau Yi Chau Artificial Islands in Hong Kong

Northern Metropolis and Lantau Tomorrow are two major projects to alleviate the acute shortage of land in Hong Kong. The Northern Metropolis is a planning area consisting of North District and Yuen Long District in northern New Territories to provide an integrated living and economic region, while the Lantau Tomorrow targets to create a third core business district by constructing artificial islands with a total area of around 1,000 hectares through land reclamation near Kau Yi Chau. Hong Kong is a densely populated city with a moderate level of earthquake risk; however, there is still a lack of seismic hazard study and yet no seismic design code. In this study, seismic hazard assessment is conducted for Northern Metropolis and Kau Yi Chau Artificial Islands, based on Hong Kong uniform hazard spectrum for the 2% probability of exceedance in 50 years. For Tuen Mun and Yuen Long, 591 drilling boreholes are collected and interpreted to build the 3D regional geological model (20km × 20km); the physics-based simulation of wave propagation is performed to investigate the complicated effect of deep sedimentary layers and mountainous terrains. On the other hand, 104 boreholes around the Kau Yi Chau Artificial Islands are collected and interpreted, and 1D nonlinear site response analyses are conducted to evaluate the seismic hazard level before and after land reclamation.