# We can't detect tsunami waves? **URL:** \ **Category:** Factual Questions\ **Created:** [December 26, 2004, 6:16pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693 "2004-12-26T18:16:56Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Bricker](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@Bricker](https://boards.straightdope.com/u/Bricker)\ **Post date:** [December 26, 2004, 6:16pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/1 "2004-12-26T18:16:56Z")
Reading about the nearly 10,000 presumed dead in Indonesia and elsewhere, I am stunned. Sunbathers were washed away by the killer wave. Of course, a disaster of this magnitude will kill people; I accept this. But sunbathers? We don’t have the ability to notice that a killer wave is coming and warn sunbathers to get to high ground? What, if any, are our capabilities to spot tsunamis following undersea quakes? ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [December 26, 2004, 6:38pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/2 "2004-12-26T18:38:39Z")
We probably have the technology to do it–at a cost. Detecting changes in water density at a distance is probably not within our current capacities. (Some squids or ASW folks might be able to correct me, here.) So the best approach would be to scan the ocean surface with radar or to have sufficient number of weather buoys to record their passing. The problem is that a tsunami at sea is simply a slightly larger than normal wave. It does not become a “tidal wave” (in the common American movie-goer parlance) until it reaches shore, so we’d have to establish radar to scan the ocean _surface_ for an anomalous wave that might be pretty hard to discover amid the normal clutter. In addition, these waves can move in excess of 300 mph, so they not only have to be detected and recognized, they need to be detected and recognized at a great distance for the warnings to be effective. There are some indicators that should warn _sunbathers_ that they are in danger, but I don’t know how much lead time they provide. For example, the oncoming wave tends to draw water to it, causing the water to recede from the beach at a distance far below that of low tide. However, if that does not happen until the wave is even 20 miles out, that gives the people on the beach a mere 4 minutes to recognize the situation and then act on it. If it does not happen until the wave is even closer, that shortens the warning even more. The best bet would probably to watch weather buoys sensing a surge beneath them, but I do not know if we are capable of distinguishing a tsunami surge from the wake of a supertanker. (Of course, with 20/20 hindsight, using a computer to analyze all buoy readings and plotting a wave front might be useful. I also do not know that India, Burma, Thailand, Malaysia, and Indonesia have quite as many weather buoys off shore as the U.S. does.) The second best (and more easily accomplished) methd is to have seismologists immediately report any strong underwater events and have the endangered shorelines warned to evacuate. We have actually accomplished that on a couple of occasions in the Northern Pacific–although not perfectly. ---
**Author:** ![Scruloose](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Scruloose](https://boards.straightdope.com/u/Scruloose)\ **Post date:** [December 26, 2004, 6:38pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/3 "2004-12-26T18:38:57Z")
There is an International Tsunami Warning System. This page has some info: [http://www.drgeorgepc.com/TsunamiFAQ.html](http://www.drgeorgepc.com/TsunamiFAQ.html) > [@](#): > > Functioning of the System begins with the detection of an earthquake which has a magnitude and location that make it potentially capable of generating a tsunami. The earthquake has to be of sufficient magnitude to trigger the alarm attached to the seismograph at the station where it is being recorded. The alarm thresholds are set so that ground vibrations of the amplitude and duration associated with an earthquake of approximate magnitude 6.5 or greater on the Richter Scale anywhere in the Pacific region will cause them to sound. Personnel at the station immediately interpret their seismographs and send their readings to the Pacific Tsunami Warning Center (PTWC)., in Honolulu, which are the headquarters for the international system (ITWS). Upon receipt of a report from one of the participating seismic observatories or as a consequence of the triggering of their own seismic alarm, PTWC personnel send messages requesting data from the observatories in the system. With this latest earthquake and tsunami, I have no idea how much warning was given, if any. I would imagine that getting the warning out to every possible place that may get hit with a particular tsunami is somewhat impossible. ---
**Author:** ![Scruloose](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Scruloose](https://boards.straightdope.com/u/Scruloose)\ **Post date:** [December 26, 2004, 6:41pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/4 "2004-12-26T18:41:09Z")
Simulposts always favor the mods. 🙂 ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [December 26, 2004, 6:44pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/5 "2004-12-26T18:44:23Z")
According to the news here, there is such a system in the Pacific, but not the Indian ocean. The time difference between the earthquake and the tsunami hitting the Indian and Sri Lankan coasts was up to two hours, so they should have been able to warn the governments further away; alas they didn’t. Such a warning should be triggered by any major undersea seismic event, not specifically the observation of a travelling wave. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [December 26, 2004, 7:57pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/6 "2004-12-26T19:57:14Z")
[Warnings could have saved thousands: USGS](http://www.smh.com.au/news/World/Warnings-could-have-saved-thousands-USGS/2004/12/27/1103996461578.html?oneclick=true) ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [December 26, 2004, 8:02pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/7 "2004-12-26T20:02:22Z")
> [@Scruloose](#): > > I would imagine that getting the warning out to every possible place that may get hit with a particular tsunami is somewhat impossible. This is what I was thinking. Even if we can detect tsunamis, getting the word out is probably very difficult. ---
**Author:** ![Mops](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mops/32/16494_2.png) [@Mops](https://boards.straightdope.com/u/Mops)\ **Post date:** [December 26, 2004, 8:28pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/8 "2004-12-26T20:28:46Z")
But would listening to broadcast radio be that rare in places like India and Sri Lanka, at least in the more urbanized areas? Given more than an hour between the wave hitting Sumatra and the wave hitting e.g. India I assume a few telephone calls between governments and from governments to radio stations ought to have saved thousands in the countries that were not hit first. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [December 26, 2004, 8:31pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/9 "2004-12-26T20:31:43Z")
> [@Eleusis](#): > > [Warnings could have saved thousands: USGS](http://www.smh.com.au/news/World/Warnings-could-have-saved-thousands-USGS/2004/12/27/1103996461578.html?oneclick=true) Sorry, apparently that link requires registration when you don’t link directly from Google News. Here is is again: > **[Breaking International News & Views](https://www.reuters.com/)** ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [December 26, 2004, 11:34pm UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/10 "2004-12-26T23:34:18Z")
From the AP article posted on Yahoo News: > [@](#): > > Scientists said the death toll might have been reduced if India and Sri Lanka had been part of an international warning system designed to advise coastal communities that a potentially killer wave was approaching. Although Thailand is part of the system, the west coast of its southern peninsula does not have the system’s wave sensors mounted on ocean buoys. As far as “getting the word out” a system of sirens have been deployed around nuclear power plants to advise the public if an event has occurred. Simple and relatively inexpensive. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [December 27, 2004, 3:32am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/11 "2004-12-27T03:32:04Z")
> [@danceswithcats](#): > > As far as “getting the word out” a system of sirens have been deployed around nuclear power plants to advise the public if an event has occurred. Simple and relatively inexpensive. Except this warning system needs to be places along the entire coastline of the country and on every inhabited island. _Not_ simple and inexpensive. ---
**Author:** ![Rikster](https://avatars.discourse-cdn.com/v4/letter/r/e9a140/32.png) [@Rikster](https://boards.straightdope.com/u/Rikster)\ **Post date:** [December 27, 2004, 3:54am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/12 "2004-12-27T03:54:55Z")
> [@](#): > > In Los Angeles, the head of the Pacific Tsunami Warning Center said U.S. officials who detected the undersea quake tried frantically to get a warning out about the tsunami. But there was no official alert system in the region, said Charles McCreery, director of the National Oceanic and Atmospheric Administration’s center in Honolulu" It took an hour and a half for the wave to get from the earthquake to Sri Lanka and an hour for it to get … to the west coast of Thailand and Malaysia," he said. We tried to do what we could. We don’t have contacts in our address book for anybody in that part of the world," he said. It must have really sucked knowing that information and being unable to do a damned thing about it. ---
**Author:** ![rfgdxm](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@rfgdxm](https://boards.straightdope.com/u/rfgdxm)\ **Post date:** [December 27, 2004, 4:01am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/13 "2004-12-27T04:01:49Z")
> [@](#): > > It must have really sucked knowing that information and being unable to do a damned thing about it. I’m quite surprised no official alert system exists for such a possibility. ---
**Author:** ![threemae](https://avatars.discourse-cdn.com/v4/letter/t/5f9b8f/32.png) [@threemae](https://boards.straightdope.com/u/threemae)\ **Post date:** [December 27, 2004, 4:20am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/14 "2004-12-27T04:20:44Z")
From what I heard, the USGS knew about it and tried to contact people about to be struck, but they just couldn’t reach people in time. Tragic that in this day of communication, some countries still don’t have emergency-broadcast type information like the US. Hopefully they will soon and similar tragedies can be avoided. What a shame. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 27, 2004, 4:24am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/15 "2004-12-27T04:24:46Z")
> [@rfgdxm](#): > > I’m quite surprised no official alert system exists for such a possibility. It’s a matter of spending priorities. Tsunamis are fairly rare in the Indian Ocean, so it doesn’t make sense to spend money on an alert system there when there are other, more common disasters that can be alleviated with that money. ---
**Author:** ![rfgdxm](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@rfgdxm](https://boards.straightdope.com/u/rfgdxm)\ **Post date:** [December 27, 2004, 4:27am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/16 "2004-12-27T04:27:12Z")
> [@threemae](#): > > From what I heard, the USGS knew about it and tried to contact people about to be struck, but they just couldn’t reach people in time. Tragic that in this day of communication, some countries still don’t have emergency-broadcast type information like the US. Hopefully they will soon and similar tragedies can be avoided. > > What a shame. No. > [@](#): > > We don’t have contacts in our address book for anybody in that part of the world," he said. The USGS said they had no contact information AT ALL. Time wasn’t an issue. Either someone in the US government failed to give the USGS that contact info, or these countries never provided it. Although I’d tend to suspect the latter. Why wouldn’t these countries have contacted the USGS to run some emergency alert drills, to make sure that both sides were prepared for such a seismic event? ---
**Author:** ![I\_Love\_Me\_Vol.I](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/i_love_me_vol.i/32/521_2.png) [@I\_Love\_Me\_Vol.I](https://boards.straightdope.com/u/I_Love_Me_Vol.I)\ **Post date:** [December 27, 2004, 5:30am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/17 "2004-12-27T05:30:51Z")
> [@dtilque](#): > > It’s a matter of spending priorities. Tsunamis are fairly rare in the Indian Ocean, so it doesn’t make sense to spend money on an alert system there when there are other, more common disasters that can be alleviated with that money. You don’t need a fancy siren on every 100 yards of seashore. A call to radio and television stations could have helped. If the stations immediately broadcast a warning, at least some people could have been saved. But then again, which stations do you call? Perhaps the national governments of the nations involved could have gotten the message through to broadcasters if they had been warned. And whatever happend to Ham radio? Or how about the internet? (yes I know the impoverished in this region don’t have internet access, but the broadcast outlets do, and the poor people (at least some) have radios). ---
**Author:** ![gouda](https://avatars.discourse-cdn.com/v4/letter/g/c77e96/32.png) [@gouda](https://boards.straightdope.com/u/gouda)\ **Post date:** [December 27, 2004, 7:04am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/18 "2004-12-27T07:04:27Z")
Coastal regions in the Bay of Bengal and in the greater Indian Ocean are well prepared for cyclones which occur with some regularity every year. Warnings systems are in place and locals in these areas know what to expect and therefore take appropriate action, even without official warnings. ALso, Cyclones tend to build up gradually, and there are plenty of visual warning signs that one is about to hit a region. In contrast, tsunamis are an unknown occurence in the Bay of Bengal. There are no visual warnings signs which locals can recognise and act on with rapidity. The vast majority of coastal inhabitants in this region are fishing communities - completely dependant on the sea, largely uneducated and not entirely well connected (wrt lines of communication) with relevant authorities. And even if they were, I seriously doubt the efficacy of a warning saying “Get out! Tsunami headed your way!” - how many of these people would even react to it? A forced evacuation on a scale of this kind is impossible in such short notice. I’m not certain, but I’d guess the above also applies to islands further west of the the Indian sub-continent. I’m curious about whether even with warnings from affected countries, was it possible to predict that even these areas would be hit with such tremendous force? Incidentally, I don’t know how aware governments in this region are that the USGS can/does provide training or drills to deal with such natural disasters. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [December 27, 2004, 8:13am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/19 "2004-12-27T08:13:47Z")
Many of the people killed in India were fishers at sea. There would be no way to warn them. India is a lot poorer than people realize. The government can’t even provide clean water, much less systems warning against rare occurances. It’s hard enough for them to manage everyday life, much less prepare for anything extraordinary. A family’s pocessions might include a string cot, a couple of pieces of cookware, and food for the next day or two. Radios, television and the Internet are out there, but not in the villages of fishermen. Roads in remote areas are trecherous and it could take hours to go short distances. Those that did have access to information would probably be more likely to flee than to run down to the shore to share the information. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [December 27, 2004, 8:26am UTC](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693/20 "2004-12-27T08:26:05Z")
According to the [url=http://www.guardian.co.uk/naturaldisasters/story/0,7369,1380040,00.html]Guardian[/url: > [@](#): > > Governments around the Indian Ocean did not act on discussions last year about introducing an early warning system, according to Dr Robert Bradnock of King’s College, London. > > “They have effective plans for the cyclones which happen every year in Bangladesh and the east coast of India, but tsunamis happen very rarely in the Indian Ocean,” Dr Bradnock said. “Last year the governments in south-east Asia were discussing having an early warning system too but because tsunamis are so rare there did not seem to be the energy behind it.” [Next page](https://boards.straightdope.com/t/we-cant-detect-tsunami-waves/281693.md?page=2)