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GEOGRAPHY AND CLIMATE
The Observatory is also responsible for the Colony's time service. Six pip signals from a special crystal clock, accurate to 0.05 second, are broadcast every 15 minutes on a frequency of 95MHz and are relayed by the various broadcasting and television stations.
Twelve seismometers are operated by the Observatory, and it prepares bulletins of all earthquake tremors recorded, and partici- pates in the Pacific Tsunami Warning Service. Hong Kong lies just outside the circum-Pacific seismic belt and has not suffered serious earthquake damage since 1918. However, an average of two to three tremors may be felt each year by residents in certain locations such as on balconies of high buildings. No such tremors occurred in 1971.
Geomagnetic measurements, which ceased in 1941, resumed in Hong Kong in April 1971, when recording of magnetic variation began in the new geomagnetic station near Tate's Cairn. This was made possible with a donation from the Nuffield Foundation for a joint project by the University of Hong Kong and the Royal Observatory.
To provide warnings of any possible health hazards due to radio- active fallout from nuclear explosions, regular measurements of beta and gamma activity in the atmosphere and in rainfall are carried out at King's Park meteorological station. The radioactivity of filtered water samples from several reservoirs in the Colony is also regularly monitored.
The Observatory answers requests for climatological and mete- orological information from various government departments, firms and the general public and issues certificates for litigation purposes and for insurance claims. The department also acts in an advisory capacity in the planning of many projects in the Colony that may be affected by meteorological conditions. Technical notes and memoirs are published on various aspects of the weather of Hong Kong and on a wide variety of related subjects.
In 1971, the Royal Observatory co-operated with the Organisa- tional Surveys Unit in a project to produce climatological and statistical summaries using equipment of the Government Computer Centre. Plans were also made to improve the existing weather services by using a computer to process all incoming meteorological data received through communication networks so that the informa- tion can be more fully utilised, particularly for the preparation of tropical cyclone forecasts under operational conditions.