Earthquakes in Iran

Iran's seismicity is a direct result of the ongoing collision between the Arabian plate and the Eurasian plate. The Arabian plate moves northward at approximately 2–3 cm per year, compressing the Iranian plateau, raising the Zagros and Alborz mountain ranges, and loading numerous active fault systems across the country.

The Zagros Fold-and-Thrust Belt along western Iran is one of the most actively deforming mountain belts in the world. It stretches from the Turkish border in the northwest to the Strait of Hormuz in the southeast — approximately 1,500 km of seismically active crust. Zagros earthquakes are typically shallow (10–20 km depth), reverse or thrust-fault events occurring as the sedimentary cover of the Arabian platform shortens against the Iranian basement. While individually often smaller than the great subduction earthquakes of the Pacific, Zagros events can be devastating when they strike directly beneath populated areas, as the 2012 East Azerbaijan earthquakes demonstrated.

The North Tabriz Fault (formerly North Tehran Fault or North Iranian Fault) runs through or near several of Iran's major cities in the northwest, including Tabriz. It has generated catastrophic historical earthquakes including the 1727 Tabriz earthquake (estimated M7.7, ~77,000 deaths) and the 1780 Tabriz earthquake (~200,000 deaths). A future major earthquake on this fault system could affect Tabriz — a city of over 1.7 million people.

The Alborz Mountains north of Tehran host numerous thrust and strike-slip faults. Tehran itself — home to 10–15 million people — sits near the North Tehran Fault and is exposed to significant seismic risk. Multiple scientific studies have estimated that a M7.0+ earthquake on this fault could cause catastrophic casualties, with some models projecting hundreds of thousands of deaths due to the density and vulnerability of Tehran's building stock.

The Bam earthquake of December 2003 (M6.6) illustrated how a moderate event can be catastrophic in Iran. The earthquake struck at 5:26 AM, when most residents were asleep, and destroyed the ancient citadel of Arg-e-Bam — a UNESCO World Heritage Site — along with most of the modern city. Over 26,000 people died, with 70–80% mortality in the affected area attributed to the collapse of traditional mud-brick (adobe) construction.