Challenges of emergency evacuation of residential areas caused by chemical release due to the earthquake: a Natech event scenario

Background: In recent decades, earthquakes, as natural hazards that caused direct effects both on communities and the chemical industry, produced many Natech events. Natech term is utilizing to describe the technological disasters caused by natural hazards. This study was conducted on the emergency evacuation challenges of residential areas adjacent to a refinery near Tehran based on H2S toxic gas release following a possible earthquake scenario. Method: This Research was an applied study at two phases in 2020. In the first phase, a review study was conducted to identify the community's previous experiences on emergency evacuation following Natech events. In the second phase, the challenges of emergency evacuation were analyzed based on the scenario of a possible earthquake and gas release from the refinery. Results: Due to the high seismic vulnerability of structures in the area affected Natech risk, the total Resident population in this area would be affected simultaneously by an earthquake and H2S gas release in concentration 30 ppm as the result of the earthquake impact on chemical facilities. Emergency evacuation would be inevitable. The existing evacuation places are very unsafe and dangerous due to having open spaces. The nearest suitable evacuation places were found in the north direction for more than 38 % of the exposed population and in the east, west, and south direction for more than 61% of them. Conclusions: The emergency evacuation challenges were discussed in 4 viewpoints, disrupted or interrupted rescue and firefighting operation, unnecessary evacuation, frequent evacuation, and evacuation behavior. The measures such as revising and updating emergency evacuation maps; public informing, training, preparedness; providing protocols and training for operational and therapeutic response teams; and coordination improvement can help resilience increasing to such disasters.