[LINK] Tsunami warning and response for Samoa

Tom Worthington tom.worthington at tomw.net.au
Thu Oct 1 13:04:34 AEST 2009

The Pacific Tsunami Warning Centre detected a magnitude 7.9 earthquake 
in the Samoa Islands region at 1748Z 29 September 2009. In response a 
Tsunami Warning and Watch was issued 16 minutes later at 1804Z (Bulletin 
1). In all 11 messages were issued, the last being 0501Z 30 September 
2009. The centre issued messages for both Hawaii and the Pacific.

Sequence	Time	Type
1	29/09/09 18:03	Expanding Regional Warning
2	29/09/09 18:05	Watch Statement
3	29/09/09 18:54	Expanding Regional Warning Supplement
4	29/09/09 18:57	Watch Supplement Statement
5	29/09/09 20:21	Expanding Regional Warning Supplement
6	29/09/09 20:23	Watch Cancellation Statement
7	29/09/09 21:34	Expanding Regional Warning Cancellation
8	30/09/09 01:58	Advisory Statement
9	30/09/09 03:03	Advisory Supplement Statement
10	30/09/09 03:57	Advisory Supplement Statement
11	30/09/09 05:01	Final Advisory Statement

Due to the closeness of the earthquake to Samoa and limitations in the 
technology available, the warning message was issued 5 minutes after the 
predicted arrival time of the Tsunami (1759Z) at the first population 
centre, Pago Pago in American Samoa.

The centre issues warnings to national authorities and there is then a 
delay while local authorities decide if, and how, to warn the public.
At best only 11 minutes warning could have been provided (assuming 
instantaneous detection, analysis and alert). Telecommunications systems 
can provide a warning within one minute.

The warning was also forwarded by email by UNESCO to the Interim Indian 
Ocean warning system mailing list. This message was dated Tue, 29 Sep 
2009 18:04:43 GMT. It was received from UNESCO approximately three 
minutes later by the Fastmail.fm mail system and a summary by SMS via 
Vodafone Australia within one minute.

Samoa uses a system of sirens and church bells to the warn the 
population of Tsunami. The USA has a system of "NOAA Weather Radio" 
which issues automated warnings. There is a NOAA transmitter in American 
Samoa, located in Pago Pago.

During a visit to Samoa in 2005 to teach web design for UNESCO, I 
noticed that while a national digital telephone network had not yet been 
installed, there was a limited private GSM service (a similar service 
existed in Tonga). There were proposals for a GSM network in Samoa in 
2007, but it is not clear how this has progressed. The significance of 
these networks is that they provide the SMS and SMS cell broadcast 
networks, which could be used to issue emergency warnings.

Labels: Emergency Alert System, emergency management, Samoa, Tsunami

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Tom Worthington FACS HLM, TomW Communications Pty Ltd. t: 0419496150
PO Box 13, Belconnen ACT 2617, Australia  http://www.tomw.net.au
Adjunct Lecturer, The Australian National University t: 02 61255694
Computer Science http://cs.anu.edu.au/people.php?StaffID=140274

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