Iran

Iran occupies one of the world's most seismically hazardous regions, squeezed between the Arabian Plate pushing northward and the rigid Eurasian Plate. Convergence of roughly 22–25 millimetres per year drives shortening across the Zagros fold-and-thrust belt, the Alborz Mountains, and the Makran [[subduction-zone]]. The Zagros fold belt in western and southern Iran is one of the world's most seismically productive mountain belts, with frequent magnitude 5–7 earthquakes along thrust faults and blind faults buried beneath the great sedimentary sequences. The Alborz Mountains north of Tehran form another major seismic belt, with Tehran itself situated near several active fault segments. The North Tehran Fault and the Mosha Fault pose catastrophic risk to the Iranian capital. In eastern Iran, major right-lateral strike-slip faults — the Doruneh Fault and the Dasht-e-Bayaz Fault — traverse the central plateau, creating a distinct seismotectonic province.

Iran's earthquake history is among the most devastating of any country. The 2003 Bam earthquake (magnitude 6.6) killed approximately 26,000 people — more than half the city's population — and destroyed the 2,000-year-old Arg-e Bam citadel. The 1990 Manjil-Rudbar earthquake (magnitude 7.4) killed 37,000 people in the Alborz foothills north of Tehran. The 1978 Tabas earthquake (magnitude 7.4) killed nearly 25,000 people in a near-total destruction of the city. The 1968 Dasht-e-Bayaz earthquake (magnitude 7.4) killed over 11,000. Earlier historical earthquakes have left enormous signatures: the 856 Damghan earthquake killed an estimated 200,000 people, and the 893 Ardabil earthquake killed approximately 150,000. Iran's death tolls are amplified by traditional construction in unreinforced adobe and brick, which collapses almost universally in moderate to strong shaking. [[intensity]] patterns from Iranian earthquakes reveal focused destruction in the near-fault zone but widespread felt shaking across the plateau.

The tectonic setting of Iran reflects the complex deformation of a collisional orogen. The Arabian-Eurasian collision has thickened the Iranian crust to roughly 45–50 kilometres and created a high interior plateau — the Iranian Plateau — surrounded by active mountain ranges. In the Zagros, the collision is primarily accommodated by folding and thrust faulting in the thick sedimentary cover, but basement-involving reverse faults also rupture. The Makran [[subduction-zone]] in southeastern Iran represents a distinct tectonic regime, where the oceanic floor of the Gulf of Oman descends beneath Iran and Pakistan. This zone produced the 1945 Makran earthquake (magnitude 8.1) and an associated [[tsunami]]. The [[epicenter]] distribution across Iran shows that essentially no region is free from seismic hazard, with the highest frequency of events in the Zagros and Alborz ranges.