Tabas-e-golshan (iran) catastrophic earthquake of 16 september 1978; a preliminary field report.

The TabaseColshan catastrophic earthquake of 16 September 1978 of magnitude M ~ 7 . 7 , the largest shock which has ever been recorded in Iran, occurred in Khorassan Province east central Iran (Fig. 1). The main shock took place in the evening, when most people were in their houses, at 19.38.18 local time (1535.58 GMT), without any felt foreshock. The preliminary instrumental epicentre is recorded at 33.145 N and 57.340 E with a focal depth estimated at 42 km by the National Earthquake Information Service of the USGS. The earthquake was preceded by a strong roaring noise described as like the firing noise of fifty cannons by many survivors in Tabas and in the adjoining villages By timing peoples’ actions in a reconstruction of the event in the epicentral region, the time lapse between the roaring noise and first arrival of the tremor was estimated at 4 4.5 seconds. Some of the survivors heard the roaring noise while lying on the ground and they described it as coming from the interior of the Earth. As the warning given by t h i s noise was short, few people reacted fast enough to save their lives by running outdoors. Although the earthquake occurred in a rather isolated and thinly populated area, it destroyed or severely damaged about ninety villages, slightly damaged another fifty villages in the region and completely demolished the ever-green oasis town of Tabas where 85 %of the inhabitants were killed (1 1,000 out of 13,000). Total fatalities were over 20,000 (see Table 1). The lunar eclipse two hours after the main shock, together with the breakdown of the Tabas Power Station during earthquake, made it impossible for survivors to start the immediate rescue operation of their families and neighbours. The earthquake which was strongly felt over an area of 1,130,000 km’, destroyed over 15,000 housing units and thirty qanats