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Observatory to enhance earthquake information release

24 May 2011

Effective from the afternoon of May 31, the Hong Kong Observatory will issue Strong Earthquake Reports for global earthquakes of magnitude 6 or above and Locally Felt Earth Tremor Reports for earth tremors felt in Hong Kong, replacing the existing practice of issuing earthquake press releases. The objective is to achieve the early release of earthquake information of interest to members of the public by making use of advanced equipment.

Under the new arrangement, the Observatory will issue Strong Earthquake Reports for any earthquakes of magnitude 6 or above, no matter whether the seismic wave has been captured by the Observatory's seismographs. When a strong earthquake occurs far from Hong Kong, the Observatory can use its new seismic analysis system to obtain data from global seismographs and compute the earthquake's parameters even before the seismic wave has reached Hong Kong. This procedure allows information on distant earthquakes to be released more quickly. In the case of strong earthquakes, the time of the earthquake's occurrence will be provided in the reports instead of the time of the earthquake recorded by the Observatory. After implementation of the new measure, it is estimated that about 140 to 160 Strong Earthquake Reports will be issued each year, similar to the number of the current earthquake press releases. For lower magnitude events, the Observatory may also issue earthquake reports if they cause significant impact. Details of issuance criteria and a sample report are given in Annex I.

For earth tremors felt locally in Hong Kong, the Observatory will issue Locally Felt Earth Tremor Reports, which will contain enhanced information, including a hyperlink to a map showing the location of the epicentre. Please refer to Annex II for an example of a Locally Felt Earth Tremor Report.

On March 23 this year, the Observatory launched a trial version of Quick Earthquake Messages on Twitter, which provided earthquake information automatically generated by computers. Records over the past two months show that the Twitter messages were on average available 40% earlier than the corresponding earthquake press releases. Details of the trial version Quick Earthquake Messages on Twitter can be obtained at the following web page:

Annex I

Annex II