To analyze the consequences of the Natech scenario of H2S toxic gas release from an oil refinery near Tehran and its effects on surrounding residential areas following an earthquake.

This research was an applied study. The Natech risk map and the end-point distance of gas release were determined using the Rapid-n software and the Worst-Case Scenario of RMP, respectively.

Regarding the high seismic vulnerability of the structures affected by the Natech risk, all residents of this area were simultaneously affected by earthquake and the toxic gas inhalation. In comparison to earthquake, response capacities were poor for Natech events, due to insufficient resources, limited accessibility, lack of planning, and unsafe evacuation places in exposed regions. Unlike earthquake, few studies have been conducted on Natech risk assessment and related consequences in Iran. Our study not only covered this gap but also revealed some dimensions of consequences of human, structural, and response capacities.

It is recommended to have plans for implementing short-term such as identifying vulnerable industries and areas, public awareness and long-term such as land use planning measures to reduce Natech risk and resilience improvement.