The world's most populous nation is also one of the world's most deadly, says Dr Paul Burton.
China is the world's most populous nation with 1.3 billion people, and is in the process of rapid demographic, economic and social change involving nationwide engineering and building construction on an unprecedented scale. With these changes, however, come some major concerns, including the increased exposure of people and property to the earthquake threat.
China has a long history of devastating earthquakes including the Shaanxi province earthquake of 1556 (estimated to have reached 8 on the Richter Scale) which is considered to have led to the largest ever loss of life from an earthquake, killing an estimated 830,000 people. In the 1920s, major losses occurred at Gulang and Haiyuan, and in 1976 the Tangshan earthquake in eastern China killed at least 240,000 people when 93% of residential buildings were destroyed. During the 20th century alone, three of the top ten deadliest earthquakes of all time, and 41% of all global fatalities from earthquakes, occurred within mainland China.
China has major contrasts in seismic activity, with high seismic hazard in central and western regions and relatively low to moderate hazard in the east, but the gross risk distribution highlights greater potential losses in eastern China. Brave investments in a number of major developments in the east are either planned, underway or nearing completion which has required the seismic threat to be taken into account. These include the financial centre of Shanghai city, the Three Gorges Dam project, the Qinghai-Tibet railway and oil pipelines charged with transferring the wealth of energy-rich western China to the energy-thirsty east of the country.
Estimation of earthquake risk requires complex modelling of seismic activity, building inventory and type, and damage probabilities for a given degree of strong ground shaking. Mitigation measures include anti-seismic engineering, proper land-use planning and adequately assigned re/insurance protections against the inevitable losses that will likely one day arise.
In light of China's continuing rapid urbanisation and building construction, there is an urgent need to evaluate hazard and vulnerability, and to build a comprehensive picture of seismic risk across the nation.