Tangshan China 1976 (CAR)
On Wednesday 28th July 1976, at 03:42 a.m. local time, an earthquake of moment magnitude 7.6 and focal depth of 17 km occurred in Hebei province of northeastern China.
The earthquake’s epicenter was very near the industrial city of Tangshan, at the time inhabited by 1.06 million people. The epicenter was located in the southern part of the city and during the earthquake a surface fault rupture progressed through Tangshan in a N40°E direction and also extended in a S40°W direction to a lesser extent, over a total distance of 100 kilometers, of which 10 km across the city.
The aftershock zone indicated, sub-surface faulting over a distance of 140 by 50 km.
The mainshock was followed by two major aftershocks on the same day (M6.5 at 07:17 and M7.1 at 18:45).
These aftershocks hit the eastern part of the epicentral area, and the cumulative damage effect was very pronounced.
By day-break it had become apparent that most of the buildings in the city and surrounding areas were destroyed, while the disaster zone was extending as far as Tianjin city situated 100 km to the southwest and another 100 km to the northeast, covering an elliptical area of 7270 km2.
Epicentral intensity was assessed at I0 = XI (on the Chinese intensity scale) in most of Tangshan city. In Tianjin city (home to circa 6 million people at the time) Chinese intensity VII to VIII was assigned, while in the capital Beijing (150 km to the west of Tangshan) the assigned Chinese intensity was VI with some damage to historic and ancient structures.
The isoseismal contours of intensities greater than IX showed pronounced northeast elongation, reflecting the northeast strike of the causative fault and covered 1,800 km2 including a zone of 27 km2 at intensity XI (in and around Tangshan) and a zone of 367 km2 at intensity X up to the town of Guye (Chinese Intensity Scale).
In the USGS EXPO-CAT database it is estimated that during this earthquake 17,524,000 people were exposed to intensity VII or higher, of which around 45% were in rural areas.
As the earthquake occurred in the middle of the night death toll from this event was immense and is officially reported by the Chinese government at around 265,000 people (although earlier reports from Hebei province authorities mentioned 655,000 deaths and unofficial estimates reached up to 800,000), while around 750,000 people were reported injured of which perhaps as many as 165,000 were seriously injured and (or) hospitalized.
This earthquake was therefore the deadliest in the World during the 20th century (surpassing the 1920 Gansu earthquake in Ningxia province of China that is believed to have killed nearly 236,000 people) and is the second worst in China’s history (the 1556 Huaxian earthquake in Shaanxi province is believed to have killed 830,000 people).
Most of the casualties were due to the collapse of residential buildings, as public buildings (except factories with night shifts) were vacant at the time of occurrence, mostly of low to mid-rise unreinforced brick masonry construction.
Detailed casualty figures by affected location have not been published, but it has been reported than in the city of Tangshan, where out of 916 substantial buildings (with 2 to 8 floors), more than 75% collapsed or were severely damaged, almost 149,000 people died incl. 13,000 non-residents.
Tangshan city was not inside the zones of China that required earthquake resistant design (in the 1955, 1966 and 1974 earthquake codes).
In addition, a significant number of buildings in the city of Tianjin collapsed or were seriously damaged.
Generally dwellings in the cities and the countryside were mainly one-story with very little earthquake resistance.
Another significant feature of this earthquake was the extent of land area that liquefied, as liquefaction was observed in parts of an area of 24,000 km2, while in the region of severe soil liquefaction south of Tangshan and up to the shores of Bohai Bay (3,000 km2), so many sandblows were produced that cultivated fields were damaged by the large quantities of sand, and the harvest was adversely affected. The sand silted up irrigation canals and water wells.
According to the Chinese engineers, this earthquake was so devastating because the seismic risk in the Tangshan region had not been realized. Almost all buildings and structures had been designed without earthquake-resistant measures, except for a few of the more important structures. In addition, the poor behavior of soft soils contributed greatly to the damage. Low mortar strength in masonry, and inadequate continuity of connections between precast reinforced concrete elements also intensified the damage.
Losses from this tremendous disaster were at the time estimated to be around 7 billion US$ or 4% of China’s GDP in 1976.
The people injured from this event was initially reported by the Hebei Revolutionary Committee to have been 779,000 of which 79,000 were seriously injured. Utsu's catalogue reports 707,000 injured of which 164,800 were seriously injured.
Many people remained missing 4 years after the event as the government could not account for or identify them. Also some individuals had been cremated before they could be identified, as there was a concern over outbreaks of diseases.
The death toll from this event was initially reported by the Hebei Revolutionary Committee to have been 655,237 but 3 years later it was revised by the Chinese government to 255,000 or 275,000. Most sources though mention 242,419 or 242,800 deaths.
148,919 (incl. circa 13,000 non-residents) killed in Tangshan city. 69,065 killed in the Tangshan municipal department (today the rest of Tangshan prefecture as well as the Qinhuangdao prefecture). 24,435 killed in the remaining affected areas (mostly in Tainjin city and Tianjin suburbs). In Chengde Prefecture's Qinglong county (nearest to the Tangshan prefecture), the earthquake was predicted, an evacuation took place and only 1 person died (heart attack), despite the total collapse of 7,000 buildings.
1548 multi-storey masonry and mixed masonry-RC buildings (2 to 5 storeys) collapsed partially or completely in Tangshan city, Qinhuangdao, Fengnan and East Mining area.
659 multi-storey masonry and mixed masonry-RC buildings (2 to 5 storeys) slightly to seriously damaged in Tangshan city, Qinhuangdao, Fengnan, Dangli and East Mining area.
Short-term homeless. Long-term homeless possibly around 2.5 million people.
It was also reported that the cost was 9 billion Yuan (equivalent to 5 billion US$ with the 1976 exchange rate). Munich Re reports 5.6 billion US$ overall economic loss. In it's 30-year retrospective report RMS estimated the loss at 10 billion US$.