Development of a building exposure model based on UAV and 360 imagery for seismic risk assessment in Nejapa (El Salvador) 

DEVELOPMENT OF A BUILDING EXPOSURE MODEL BASED ON UAV AND 360 IMAGERY FOR SEISMIC RISK ASSESSMENT IN NEJAPA (EL SALVADOR) We develop an exposure and seismic vulnerability database for seismic risk applications in the city centre of Nejapa (El Salvador). This area, as most of the country, is characterised by a very limited availability of open cadastral data, street-level and aerial imagery and LiDAR point clouds.We carry out an on-site campaign integrating aerial street-level images. Aerial images are captured in a drone flight and are used to identify building footprints and roof properties. Façade photos are obtained with a 360º camera during a walk-down survey, provindng information about the number of storeys and wall materials. These data are combined to generate a 3D model of the city centre. Next, buildings are identified, characterised, and assigned a vulnerability and fragility models.This database is used to estimate seismic risk for a simulated Mw 6.7 earthquake on the Guaycume fault near the city. Results show that 71% of buildings would suffer complete damage and 68% of the population would be homeless, with losses exceeding USD 15 million.A dashboard integrating these data are set up to help disseminating the results of the study into stakeholders and decision makers.