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Historical Earthquakes in China

George Pararas-Carayannis

(Excerpts from Unpublished Manuscript)

INTRODUCTION

Collision of India with the Asian mainland during the earliest Eocene (~50 Ma) has resulted in the growth of the world's largest orogenic belt, the Himalayas, and the associated Tibetan plateau. The seimotectonic tectonic evolution of China is characterized by the merger of several microcontinents throughout the entire Phanerozoic (Zhang et al., 1984; Hendrix and Davis, 2001). The collision and associated convergence and extension has created 64 major tectonic zones in China, which can be subdivided into a smaller number of tectonic "regions" (Zhang et al.,1984; Yin and Nie,1996).


Thus, China is located in one of the most active seismic regions of the world that has been plagued by numerous destructive earthquakes during its long history. The most significant of the historical earthquakes, in terms of lives lost, was that which occurred in 1556. However, since 1900 China has experienced several more destructive earthquakes. The most destructive earthquakes of the 20th Century were those of 1927 in Tsinghai, of 1932 in Gansu, of 1933 in Sichuan, of 1969 in Bohai Sea, of 1970 in Tonghai (Yunnan), of 1974 in Zhaotong (Yunnan), of 1975 in Haicheng, and of 1976 in Tangshan (Hebei Province) . The more recent earthquake of May 12, 2008 in Sichuan Province was the latest of the more destructive earthquakes that have struck China in the new millennium. The following is a brief account of the 1556 event and of some of the more destructive earthquakes since 1900.

The Great China Earthquake of 1556


The worse natural disaster in recorded history - at least in terms of lives lost - was caused by an earthquake in Hausien, in the Shaanxi Province of China in the morning of 23 January 1556. In Chinese historical record, this event is often referred as the "Jiajing Great Earthquake" because it occurred during the reign of Emperor Jiajing of the Ming dynasty. The "Shaanxi Earthquake" as it became later known, had an estimated magnitude ranging from 8.0 to 8.3 on the Richter scale (final assigned Moment Magnitude of 8), and had an estimated intensity of XI on the Modified Mercalli scale. Its epicenter was near Mount Hua in Shaanxi, close to present day Weinan city. The earthquake was responsible for the devastation of 98 counties and eight provinces in Central China, but particularly destructive in the Province of Shaanxi. The destruction extended over an area of 500 miles. In some of the counties, the average death toll was estimated to be about 60 percent of the population. According to historical records, a total of 830,000 people lost their lives, most from the collapse of poorly constructed houses and of Loess cave dwellings.

Destructive Earthquakes in China in the 20th Century in relation to the most recent earthquake of May 12, 2008 (modified graphic of Western Australia Un.)

The Haicheng Earthquake of February 4, 1975


On February 4, 1975, Haicheng, a town with about 100,000 inhabitants in the Liaoning Province of northeast China, was struck by a 7.3 magnitude earthquake. As early as 1970, the State Seismological Bureau, had identified the Liaoning Province as an area of high earthquake risk. Six months before the earthquake, there had been a series of smaller quakes in the region - which intensified on February 3rd.

Based on studies of such precursor events and on unusual behavior exhibited by animals, a warning was issued by local authorities on February 3rd and in the early morning of February 4th.Thus, when the earthquake struck at 7:36 p.m. that evening of February 4, there were few lives lost as most inhabitants had evacuated to safer places. The death toll was relatively smaller than what could have been without the warning. Only 1,328 people lost their lives. However property damage was high.

The Tangshan Earthquake of July 28, 1976


No other earthquake in this century has been as catastrophic or has claimed as many lives as the earthquake that struck the city of Tangshan in Northern China on July 28, 1976 (27 July 1976 local date). Tangshan, a thriving industrial city with one million inhabitants, is located in the Province of Hebei, about 95 miles east and slightly south of Beijing and about 280 miles southwest of Haicheng - where in the previous year another very destructive earthquake had occurred. Although the region had experienced moderate seismic activity in the past, there were no foreshocks this time, and no warning.

China's Seismic Zones

Collision of India with the Asian mainland during the earliest Eocene (~50 Ma) has resulted in the growth of the world's largest orogenic belt, the Himalayas, and the associated Tibetan plateau. The seimotectonic tectonic evolution of China is characterized by the merger of several microcontinents throughout the entire Phanerozoic (e.g. Zhang et al., 1984; Hendrix and Davis, 2001).The collision and associated convergence and extension has created 64 major tectonic zones in China, which can be subdivided into a smaller number of tectonic "regions" (Zhang et al.,1984; Yin and Nie,1996.

The eartquake (with a magnitude reported in the literature as ranging from 7.5 to 8.0), struck at 3:42 a.m. in the early morning hours of July 28, the worst time when the city was asleep. What made matters worse, was the fact that this city is located in the center of an area with major crustal faults on four sides and most structures had been built on unstable, alluvial soils. Only a few of its structures were earthquake-resistant. The earthquake, with its epicenter right on Tangshan, broke a five-mile section of a 25-mile long fault that passes through the city. Along the west side of this fault the land moved five feet northward in relation to the land on the east side. The east block tipped downward at the northern end of the break and upward toward the south end.

Hotel in Tangshan


 

 

 

Complete Destruction of the City of Tangshan by the July 28, 1976 Earthquake (Photo source: China Earthquake Administration)

 

Ground motions lasted for about 90 seconds and, during this time interval, about 90 percent of the houses and buildings in Tangshan collapsed. Over a four-by-five mile area the devastation of the city was nearly total. The force of the ground motions were so strong that people reported being thrown in the air. Within seconds, thousands died. Property destruction was unbelievable. Bridges, railroads, homes, factories were completely leveled.

In the harbor city of Tientsin, 60 miles to the southwest, and in Beijing to the west, the strong ground motions forced thousands of frightened people into the streets seeking refuge from the aftershocks. The extent of the destruction and number of deaths in Tangshan and elsewhere in the region has been uncertain. According to official reports a total of 242,769 people died and 169,851 were severely injured. However, based on the density of population, it was fairly accurately estimated that there were at least 655,000 people dead and 780,000 injured. These figures make the 1976 Tangshan earthquake, the second worse earthquake in recorded history. The most destructive earthquake ever, as reported earlier, occurred in 1556.

Since 1976 the city of Tangshan has been growing and its population has increased by more than 50 percent. A number of new structures have been built, including high rise structures like the Phoenix Hotel with a height of 112 meters. Although most stuctures built since 1976 have been designed to be earthquake resistant and in accordance to revised seismic construction codes, it is still uncertain what damage could be inflicted on the city of Tangshan when another stong earthquake strikes again in the future.

REFERENCES AND ADDITIONAL READING

Hendrix, M.S., and Davis, G.A., 2001, Paleozoic and Mesozoic tectonic evolution of central Asia: from continental assembly to intracontinental deformation: Boulder, Colo., Geological Society of America, vi, 447 p.

Yin, A., and Nie, S., 1996, A Phanerozoic palinspastic reconstruction of China and its neighboring regions, in Yin, A., and Harrison, T. M., eds., The Tectonic evolution of Asia: Cambridge [England] ; New York, Cambridge University Press, p. 442-485.

Zhang, Z.M., Liou, J.G., and Coleman, R.G., 1984, An outline of the plate tectonics of China: Geological Society of America Bulletin, v. 95, p. 295-312.

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Last update: March 23, 2013