Initial reports of American Samoa quake

Updated September 30, 2009 08:55:30

The US Geological Survey is reporting that a 7-point-8 magnitude earthquake has hit just off the coast of American Samoa, just 180 kilometres from Hihifo in Tonga and 200 kilometres from Samoa's capital, Apia.

Just moments ago, the quake was upgraded by the Pacific Tsunami Warnign Centre to an 8.3 magnitude quake.

Initial measurements of tsunami activity include the Samoan capital, Apia, at point-7 of a metre, or 2-point-3 feet, and of course the capital of American Samoa, Pago Pago at a very dangerous 1-point-57 metres or 5-point-1 feet.

Niue, Wallis and Futuna, Tokelau and Cook Islands are also within short distance of the quake and a possible tsunami, as is the top-end of New Zealand. Reports are still coming in, but the massive quake was also very shallow at 21 miles under the surface, and the Pacific Tsunami Warning Center has issued a tsunami warning for all regional Pacific states.

First we're going to the Pacific Tsunami Warning Center in Hawaii for the latest on the initial warnings that were issued less than an hour ago.

Presenter: Geraldine Coutts
Speaker: Nathan Becker, Pacific Tsunami Warning Center in Hawaii

FOR THE LATEST NEWS ON AMERICAN SAMOA SEE http://www.radioaustralianews.net.au/tags.htm?tag=american-samoa

BECKER: It sounds to me like you only have our most recent bulletin which only went out a few minutes ago. It's good news that you have it. What I can add to that is that we did record a tsunami in American Samoa and Western Samoa on our instrumentation there, in Western Samoa it's about .7 metres, seven tenths of a metre, and in American Samoa is 1.5 metres. So we know the tsunami has been generated but we have not yet determined which way it is headed, if it is headed out into the open ocean or not. But you're quite correct, those islands nearby are tsunami warning.

COUTTS: Now, because one of the original warnings also included Fiji. So is it right across to east to west Pacific that are on standby now?

BECKER: Fiji is still in a warning. We base our warning on the travel time of a tsunami, of how fast it moves through the water and so the areas that are within a three hours of arrival of the wave we put into a warning and that includes the islands you've mentioned.

COUTTS: So how fast is this one moving?

BECKER: Tsunamis in the open ocean move quite fast. I try to make a conversion in my head, but it is on the order of several hundred kilometres an hour. They move very fast in deep water.

COUTTS: Okay, so American Samoa and Western Samoa probably in the front line of this one this time around?

BECKER: Right, they were the first to receive the waves and so we are waiting to see if the wave shows up at any other instruments both offshore based and out in the deep water. Those are buoys to see if there is a wave heading anywhere.

COUTTS: Now, how big were the waves that hit both Western and American Samoa?

BECKER: Western Samoa is at seventh tenths of a metre and American Samoa got one and a half metres, almost 1.6 metres. Those are big enough to be dangerous. If you were on the shore and if such a wave came in, that could sweep you off your feet, it could damage boats in the harbour, it could flood low lying areas. So Samoa was certainly an area that is likely to have experienced some damage. A similar wave arriving anywhere else would pose a similar threat.

COUTTS: Now, has your bureau been in touch with American or either of the Samoas to have a chat to them about what's going on and what impact they actually experienced?

BECKER: I was on the phone earlier when the earthquake happened with an official in American Samoa. They felt the earthquake, they knew there was a large earthquake and I suspect they self-evacuated before we even got a message out, because they were right there. But I don't have reports of damage or injuries.

COUTTS: Now we need to be more concerned? I mean it is worrying for everyone, but do we need to be more concerned about the low lying atolls who have already experienced devastation just from regulation high tides, such as Tuvalu and Kiribati?

BECKER: Not necessarily, much of the damage depends on the sea floor topography around the islands, it is whether it has reefs, a number of things like that. So we put these areas in the warning in the ere of the side of caution, but some of the islands may not see anything at all, even if they are right in the middle of the wave. It's just an artefact of the physics of the seawater that behaves that way. Shorelines that have the right kind of sea force structure offshore could actually amplify a wave, so we're just being very cautious about this.