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Island, which is about 35 km southeast of Hong Kong Observatory. This is the largest earthquake
observed within 100 km of Hong Kong in the past 500 years. Another strongly felt earthquake is the
1918 Shantou earthquake of magnitude 7.4 which is about 300 km away from Hong Kong. These
records agree with the "Seismic intensity zonation map of china" published in 1990 by the State
Seismic Bureau of China (now the China Seismological Bureau). The newest published "Seismic
ground motion parameter zonation map of China" (GB 18306-2001) predicted that a maximum ground
shaking of exceeding 0.15g at rock site is expected in Hong Kong at least once in every 475 years
(Wong et al., 1998a-b). This shaking will further be amplified when topographical and soil effects are
considered (Wong et al., 2000; Wong et al. 1998a-b; Chau and Lo, 2001). However, when the 1874
Dangan Island earthquake and the 1918 Shantou earthquake occurred. Hong Kong is still a small
fishing village (see Fig. 1). However, Hong Kong is now a major financial centre and one of the most
densely populated cities in the world. Any interruption to critical facilities and business operations may
have serious social and economical consequences (see Fig. 1).
(a)
Figure 1. (a) Central in 1870s; (b) Central in 2000
For instance, Newcastle city in Australia, an area of low to moderate seismic risk similar to Hong
Kong, was attacked by a relatively small magnitude earthquake (M=5.6) on December 28, 1989
causing about 20 billion Hong Kong dollars of damage and 13 deaths (EEFIT, 1991). In total, 50,000
buildings were damaged, 300 buildings were eventually demolished, and 162 people were hospitalised.
The Unexpected Catastrophe
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Figure 2. The unexpected Newcastle earthquake on December 28, 1989, Australia.