The report say it can't be relied on to detect the giant waves as they approach the U.S. coastline. The system, known as DART, or Deep-ocean Assessment and Reporting of Tsunamis, was expanded from six deep-ocean buoy stations to 39 in the months following the massive 2004 earthquake off Indonesia.
Presenter: Geraldine Coutts
Professor John Orcutt, from the Scripps Institution of Oceanography
ORCUTT: Well, they're some very good things about them. It is the first time we've had a tool like this available in such a large number in order to allow us to measure waves at sea that are associated with tsunamis. The downside is that the systems have not operated as continuously as one would hope.
COUTTS: Why is that?
ORCUTT: In many cases, particularly for the United States, many of these buoys, we found in the report, at anytime a third of the buoys would not be operating.
COUTTS: But why is that, is that because they are too far apart, so you need to fill in the gaps?
ORCUTT: No, they just won't operate continuously over the designed life that they are originally built for and so they actually go out of service because of failures with the bouys. Many of these operate in very, very difficult oceans and seas like the Gulf of Alaska, for example.
COUTTS: Well, what can be done to improve on the system, to make sure it is continuous?
ORCUTT: A lot more work needs to be done with the buoys upgrading them, looking at failure modes for these things. Often the buoys are tended once a year, in fact that is what the funding available allows them to do and often they tear from metal borings and go basically walking about the Pacific and it's very difficult to go back and retrieve these and retrieve the mooring lines to sort out what the failures were in the systems.
COUTTS: And have you got any clue to that yet?
ORCUTT: Not yet, there is a lot of work going on and from what I can actually tell, the NOAA office is responsible for this, the National Data Buoy Centre, is working a great deal on the problem and there are indications they are making improvements.
COUTTS: Well, you have expanded and located a number of them around Pacific Oceans Ring of Fire to give advanced warning to Washington. Were they in the Pacific prior to 2004 or are these the new additions?
ORCUTT: Well, these are additions to the system. They are also more modern. They were a few buoys prior to the Sumatra tsunami, but they have expanded as you noted in the beginning substantially since that time.
COUTTS: So what kind of coverage are you looking for and I guess what I am really asking is how long is going to be before it is foolproof?
ORCUTT: I am not sure of anything one does at sea, having been at sea several years of my entire life, that anything at sea is foolproof.
COUTTS: What is the best, how good can you get it?
ORCUTT: Oh, I think one should be able to get the performance of the systems themselves about 90 per cent that is if a buoys is put out there is a 90 per cent likelihood it will operate through the year.
COUTTS: With the failure rate that you've experienced, is it the best way to go about it or is there another system that we should be looking at in place of this buoy system?
ORCUTT: Well, there is an alternative to this and well, Australia is certainly familiar with this. The Comprehensive Test Ban Treaty operates a series of hydrophones, three stations in the Indian Ocean, in fact, one off the western coast of Australia and these are all cabled to shore rather than using buoys offshore. Now it is expensive to run cable to each one of these sites, but when you look at a 10 year, 20 year and even a 50 year time cycle for this, the cost for the cabling becomes very attractive in terms of the cost for bringing ships back and forth and trying to maintain the buoys on the surface. So we recommended in our case that NOAA undertake a review of this whole system from using a systems engineering point of view to determine what the best solution to this problem might be, so it may not be buoys, it might be cabled.
COUTTS: And is cable more reliable?
ORCUTT: Eh, generally yes, although there are good counter examples for that. I just finished a review of a installation in the Indian Ocean that Crozet Island, with a cabled system. Now Crozet is in the Antarctic Circumpolar Current, that is a very severe difficult part of the world to work in and the cabling there has over the last decade completely failed, so that there are no operating systems at Crozet. The others continue to operate off the west coast of Australia and near Diego Garcia.