Street-block collapsed buildings assessment: A case study of Banqiao District, New Taipei City

After a large-scale earthquake, it induces a large number of building collapses and casualties, especially in urban areas. In order to make prevention and response plans before earthquakes, various earthquake loss estimation systems have been developed. The commonly used units of analysis in those systems include grid and village (or administrative district). However, grids are not consistent with streets/roads, making grid-based analyses impractical for evacuation and rescue road planning. As for village-based analyses, a unit covers large spaces and might fail to point out the precise location of collapsed buildings. Therefore, street block, which is a block surrounded by roads, is proposed by the authors as an alternative. To figure out the better analytical units, this study compared street-block-based analyses and village-based analyses. Banqiao District in Taiwan was used as a case to delineate the street blocks by roads with a width of 6 meters or above. Building collapse assessment under peak ground acceleration (PGA) of 400 Gal and 550 Gal demonstrates that street-block-based analyses outperform village-based analyses in terms of locating the collapsed buildings. Moreover, street blocks are readily available for planning evacuation or rescue roads for their consistence with the road network. Results of this study suggest that in urban areas, the higher-resolution spatial analyses of earthquake loss estimation can be made by street-block-based analyses.