Earthquake Engineering Research - HKU Libraries - The University ...

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Some people were injured while two houses collapsed, boulders were dislodged from slopes and some
retaining walls collapsed. According to the Daily Press, the ground shaking was felt along NE to SW
direction. There were also observable ground waves, bells rang and water in the harbour was "rough and
buoyant" (Lee and Workman, 1996). Thus, Dangan Island area is definitely a potential seismic source
that will generate earthquakes affecting Hong Kong. A closer look of the geological setting in South
China reveals that there is a large fault system in the northern South China Sea. This fracture zone is
called "Binghai Fracture Zone' or "Littoral Fault Zone" (see Fig. 6). Figure 6 is modified from Lin and
Xie (1996). Along this fracture zone, there had been the 1918 Shantou earthquake of magnitude 7.4
which is about 300 km away from Hong Kong to the east; and there was also the 1605 Qiongshan
earthquake of magnitude of 7.5 about 450km to the west of Hong Kong. There is, however, a "largeearthquake-missing
zone" in the middle around Hong Kong.
Large-earthquake- \ ^ {
missing -zone x j
Earthquake with ji!
^
Figure 6. Large-earthquake missing-zone near Hong Kong of the Binghai Fracture Zone
Figure 7, Fault system of the Binghai Fracture Zone south of Hong Kong and Dangan Island
In 1982, in order to understand the basement structure characteristics of oil-bearing basins off the Pearl
River Delta region, seismic profiling of the South China Sea was conducted by the Institute of
Geophysics, Institutes of Acoustics and South China Sea Institute of Oceanology (Xia, 1985). A deep