Earth Observation Data to Support Post-Hazard Damage Assessment: A Case Study of the Appiatse Explosion in Ghana

Abstract

On Thursday, January 20, 2022, a motorbike allegedly collided with a truck carrying about 10 tonnes of ammonium nitrate explosives. The explosion caused a blast that created an 18 m diameter crater at the centre of the road and leveled almost the entire village of Appiatse, located in the Prestea Huni Valley District in the Western Region of Ghana. During such disasters, whether natural or anthropogenic, rapid assessment is crucial for an appropriate and effective emergency response. The Appiatse incident resulted in detrimental environmental damage, including the dispersion of particulate matter, dust, soil, and water pollution in the catchment area. Similarly, the high levels of ground vibration caused by the incident resulted in the razing down of most of the structures which were constructs of wattle and daub plastered with concrete. Earth observation (EO) technologies, such as satellite imagery and Unmanned Aerial Vehicle (UAV) data, play a crucial role in disaster management by providing accurate and detailed assessments of damage, enabling effective emergency response and recovery efforts. The impact of the Appiatse explosion was detected by the Enhanced Pollution Management (EPM) EO service, piloted in Ghana, through a time-series analysis. In this research, a damage assessment was carried out using EO data. A collection of Sentinel-2 (10 m resolution) optical satellite images, Synthetic Aperture Radar (SAR) images, and aerial images obtained from a UAV survey (3 cm resolution) were used for the analysis. The damage assessment map of Appiatse provides insights into the extent and severity of the impact, demonstrating the value of integrating various EO data sources for detailed post-hazard damage assessment. The findings from the current research highlight the lack of compliance with the protocols for the transport of hazardous chemicals in Ghana and highlight the need to strictly adhere to safety protocols prescribed by relevant authorities to ensure environmental safety and curb such incidents in the future.