but caused folding at the surface. A previously unmapped thrust with little surface expression, the Abdareh fault, has been identified from the disruption of earlier drainage systems by the growth of the fold in its hanging wall, and is thought to be responsible for the earthquake. Such structures are known as blind thrusts, and have been responsible for many destructive earthquakes in Iran and elsewhere. The geomorphological effects of this particular fold have been partly obscured by the presence of an earlier Neogene topography. The Qazvin region was hit by an even greater earthquake in 1962, which killed 12,200. In 1990 a rupture killed over 40,000 people, injured 60,000, and left more than 500,000 homeless. Damage and casualties The earthquake occurred at 02:58 UTC (7:28 a.m. Iran Standard Time), while many of the estimated 60 million Iranians affected were in their homes. Its duration was seven seconds, and the epicenter was near the settlement of Bou'in-Zahra in the Khar river valley, a mountainous farming region about from the provincial capital of Qazvin. The greatest damage was across an area best known for its seedless grape harvesting, a getaway for wealthy residents of Tehran. At least 230 people were killed, 1,500 injured, and 25,000 left homeless. An earlier death toll was reported as 500, but this number was believed to be inflated once it became known that some of the severely injured had been mistaken for dead. Most of the dead were women, children and the elderly, as many of the men were working in local vineyards. Over 20 aftershocks were recorded, with magnitudes up to 5.1 on the moment magnitude scale. At least three of these caused further casualties and damage, most of which were within a radius of the main shock. An estimated 5,000 buildings were damaged beyond repair. In the Qazvin province, 120 buildings were demolished and 50 villages suffered massive damage. In the neighboring Hamadan province, 45 villages were destroyed. A large majority of houses in the region were single-story masonry buildings, and virtually all of these collapsed. As non-engineered structures, these could not withstand seismic forces, with structural failure and collapse resulting from wall-to-wall separation and the lack of structural integrity and of a proper lateral system of resisting. Newer structures built in accordance with the Iranian code of practice for seismic-resistant design fared much better. Damage to the historic Kharaqan tomb towers, which were in