Contribution of archaeological data to studies of earthquake history in the Iranian Plateau

We use archaeological evidence to identify ancient earthquakes in the vicinity of large 20th century events in the Iranian Plateau. Two large earthquakes on the Zagros Main Recent Fault were preceded by historical earthquakes in AD 1008 and AD 1107 and by earthquakes in the intervals AD 224–459 and 1650–1600 BC, giving return times of 1800–2100, 500–800, and 850–950 years. The AD 1962 (Ms 7.2) Bo’in Zahra earthquake on the Ipak fault in north-central Iran was preceded by an earthquake in 2000–1500 BC recorded at the Sagzabad mound, a return time of 3500–4000 years if there are no missing events. The AD 1990 (Ms 7.3) Rudbar–Tarom earthquake in the western Alborz Mountains was preceded by an earthquake in 1000–800 BC recorded at the Marlik mound, a return time of 2800–3000 years. The AD 1948 (Ms 7.2) Kopeh Dagh earthquake that destroyed Ashkabad, capital of Turkmenistan, was preceded by an earthquake in 10 BC–AD 10 recorded at Mithradatkert (Nesa) mound and by an earthquake in 2000 BC recorded at Ak Tapeh mound. Assuming no missing earthquakes, this region has an earthquake return time of about 2000 years. In Khorasan province, which was struck by a sequence of large earthquakes from AD 1936 to 1997, a mosque at Qa’en was destroyed in the mid-11th century AD, probably the historical earthquake of AD1066. In the absence of palaeoseismic investigations, archaeology offers the promise of recording earthquakes through more than one seismic cycle in different regions of Iran.