Urban seismic risk assessment and loss estimation for Hanoi City

In this paper, the HAZUS-MH’s methodology is modified to estimate building damage and human loss due to earthquakes in five downtown districts of Hanoi city. The main modifications include: (1) applying the HAZUS-MH building classification to the housing data in Hanoi; (2) customizing the HAZUS-MH population exposure model, taking into account the behavioral norms of the Hanoi urban community; and (3) applying spatial analysis techniques in a GIS environment to calculate the number of casualties inside the buildings destroyed by the earthquake. The ground shaking ability in Hanoi region was assessed using both deterministic and probabilistic approaches. A digitized building database and the last updated 2019 census data of Hanoi city were used for loss estimation. The results of building damage estimates show that slight and moderate damage states account for the highest proportion, but do not exceed 30%. The temporal distribution of casualties in the study area represents a general rule for all casualty levels, that is, the number of casualties decreases over the hours from 2:00 a.m., 2:00 p.m. to 5:00 p.m. By prioritizing Vietnamese standards and tailoring the population exposure model to local conditions, the customized methodology offers numerous advantages when applied to Hanoi and other urban areas in Vietnam. The results of this study also demonstrate the feasibility of conducting earthquake risk assessments in an urban area like Hanoi, which has never been affected by earthquakes, and in a country with low seismic activity like Vietnam.