Reconnaissance surveys after June 2022 Khost earthquake in Afghanistan: implication towards seismic vulnerability assessment for future design

The Khost earthquake in Afghanistan on 22 June 2022 was one of the deadliest, resulting in over 1500 deaths, 3500 injuries, and the collapse of 15,000 houses in the rural areas of Paktika and Khost provinces. This event provided an opportunity to investigate the damage to residential buildings and public infrastructure. A post-earthquake reconnaissance survey was conducted 2 days after the event in Gayan, Barmal, and Spera. Damage data were collected during the survey and field investigation, indicating that more than 50% of the houses and public infrastructures had completely collapsed. For damaged sites, a one-dimensional seismic response analysis is performed, which provides a link to understanding the damage scenario across the province. Further, the rapid damage assessment data were employed to propose vulnerability function for rural houses, which highlighted the probability of damage for various damage grades under varying seismic environments and building material characterisation. The damage probabilities rise to 17.5%, 45.5%, and 11% for slight, moderate, and heavy damage, respectively, indicating that the examined houses retain their basic performance but may sustain some moderate damage at this level of earthquake intensity. The shortest source-to-site distance, poor-quality construction materials, and an irregular town layout were the main issues identified during the surveys and are thought to have had a significant impact on the extent of the destruction. The data set and vulnerability functions provided will aid in assessing earthquake hazards in this region.