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VI
OPENING ADDRESS
By Ir, Dr. Hon-kwan Cheng
Chairman of Hong Kong Housing Authority
Professor Ko, Professor Liu, Distinguished Guests, Ladies and Gentlemen,
I am very pleased to attend the second leg of the International Conference on Advances and
New Challenges in Earthquake Engineering Research. And I am greatly honoured to be given
the opportunity to address such a distinguished audience. In this part of the Conference, we
will be focusing on the specific challenges for regions of moderate seismicity, and explore
how emerging technologies and new design philosophies will impact building design in these
regions. I would like to take this opportunity to briefly discuss the challenges that we face in
Hong Kong and the recent development of earthquake engineering here. Since our experience
should be quite typical for places with moderate seismicity, I hope this would serve as a
useful backdrop for our discussion over the next two days.
Probably because Hong Kong has never been seriously damaged by earthquake, the structural
design of buildings and other structures here do not cater for seismicity. At present, there is
no such requirements in our ordinance or design codes. Up until not too long ago, most
building designers here believed our risk of being struck by an earthquake is low. However,
this perception has been under challenge in the past few years.
Recent studies have shown that seismic intensity for the Hong Kong region with a 10%
probability of exceedance in 50 years was assessed to be of intensity VII. This is consistent
with the intensity given for Shenzhen located immediately north across the Hong Kong border.
In addition, according to the Seismic Ground Motion Parameter Zoning Map 2001, the peak
acceleration for Hong Kong Island is 0.15g while that for Kowloon and the New Territories is
0.10 g. The characteristic period for the Hong Kong region is 0.35 second. These classify
Hong Kong as a region of moderate seismicity.
This classification is indeed consistent with historical records. In 1991, our Government
traced past earthquake data as far back as 900 years ago in places within a 350 km radius from
Hong Kong and found that Hong Kong experienced at least two moderate earthquakes in
1874 and 1918 respectively. On 16 September 1994, buildings on the reclamation areas of
Hong Kong experienced substantial vibrations due to a strong far field earthquake. That has
been the strongest earthquake felt by us since 1918.
Local engineers also used to believe that given our moderate seismicity, our design provision
for strong typhoon forces should be sufficient to withstand the earthquake energy. This has
likewise been put in doubt. Recent studies on comparison between earthquake and wind
loads in Hong Kong scenarios showed that for low rise buildings, the inter-storey shear and
overturning moment from earthquake loadings are generally higher than those from wind
loadings; and for medium to high-rise buildings, there is a strong possibility that the
earthquake shear and moment effects will exceed those from wind at the upper storeys.
I am pleased to note that attention is increasingly being paid to the issue of seismicity in Hong
Kong in recent years. Through the conferences and seminars organised by the local
professional bodies, we have witnessed a gradual change of minds, with more and more
practitioners becoming aware of the potential risks. The local academics have also focused
more research resources in studying sesimicity in the local context, providing us with crucial