Tsunami Lessons

Posted by on April 1, 2005  /  8 Comments

Ten preliminary lessons of the 28th March 2005 Sumatra great earthquake (Photo Source)

LIRNEasia, together with Vanguard Foundation, intends to systematically analyze the Sri Lankan media response to the great earthquake of the 28th of March. However, it appears useful to draw some preliminary lessons from this tragedy which has cost over 1,000 lives, including the people of Nias and other islands and those in Sri Lanka and elsewhere who died as a result of the warnings. The conclusions are preliminary; comments are welcome.

# Earthquake hazard detection is easy; tsunami hazard detection is not. One cannot simply infer the existence of a destructive tsunami from an earthquake. Whether a tsunami has been generated and the direction it is likely to go requires the application of expert judgment.
# Issuing tsunami warnings is not difficult; avoiding false warnings is. It is said that the Pacific Tsunami Warning Center and its predecessors have never failed to predict a tsunami; the problem is that they have issued a lot of false warnings in the process. The key in the now destabilized Sunda Trench area is to install equipment to reduce the issuance of false warnings such as that issued on the 28th of March. I do not in any way suggest that the authorities and the media should not have issued the warnings on this particular occasion, or that there was anything intentionally wrong in its issuance. So soon after a catastrophe of 26th December 2004, the option of not issuing a warning did not exist.
# The proposed Asian tsunami warning center is a boondoggle; Hawai’i worked perfectly on the 28th of March; duplicating a tsunami warning center will not save lives. The earthquake occurred at 1610 hrs UMT (2210 hrs SLT). The tsunami bulletin was issued by the Pacific Tsunami Warning Center at 1626 hrs UMT (2226 hrs SLT). The gap was 16 minutes, the same as on 26th December 2004. Can an Asian tsunami warning center do better? The communication of the earthquake hazard detection depends on direct measurement of waves that go through the earth and on its surface and on telemetry. If there were tide gauges and deep sea tsunami detection devices, those signals would be communicated using radio signals. The time taken to communicate with Ewa Beach Hawai’i and the location of the Asian Center would be the same. The time taken to communicate from Hawai’i is no different to that from an Asian location. It is better to rotate the best Asian scientists through PTWC than to go to the trouble of setting up a new center in Asia, assuming that the posturing of the Indian and other country representatives will allow such a center to be built in the first place. Note to the diplomats: lives are involved here, not national prestige.
# Historical data are important for benchmarking the response. For Sri Lanka, the critical time was 1740 UMT (2340 hrs SLT), 90 minutes after the earthquake. It was possible to arrive at this conclusion from the experience of the 26th December 2004, when the tsunami hit the coast near Kalmunai at around 0230 hrs UMT (0830 hrs SLT), approximately 90 minutes after the earthquake. The three-hour time period that some in the media were talking about may have been useful in generating the all-clear decision (if a tsunami had not been generated within 3 hours, one could assume a tsunami would not come), but it was not relevant for warning purposes.
# The Internet and messaging are faster than conventional mass media. Many people in Sri Lanka were aware of the earthquake well before the BBC, CNN or other news channels began to broadcast news about it. I received an SMS at 1658 hrs UMT (2258 hrs SLT), confirmed it on the Internet and informed several people before the news was conveyed on international cable channels.
# Media must have pre-agreed procedures for the issuance of alerts and warnings. The reason the Sri Lankan TV channels took until around 2330 hrs SLT (to be confirmed through a questionnaire and interviews) to broadcast warning messages was the absence of standard pre-agreed procedures. In one case, the colleague who contacted the media channel was told that they were awaiting clearance from the Department of Meteorology. Some channels interrupted their programs to make live announcements and went back to the programs. The problem with this approach was that a viewer who was flipping channels or just tuned in could have missed the message. Others linked live to ANN, BBC and CNN. As time went by, the crawlers in Sinhala appeared.
# Evacuation procedures and drills are important. All who participated in issuing warnings and organizing the evacuation deserve our praise for effort. But this does not mean that we should take the actions of the 28th of March as any kind of model for the future. The fact that widespread looting did not occur was luck, more than anything else. In actual fact, most families left behind one or more members in their homes when they evacuated.
# Congestion is a problem that needs to be addressed and also embraced. Close to midnight, the telecom networks began to get congested as the word spread. It is not practical to design networks that will not be congested by sharp spikes in use such as those engendered by disaster warnings. The telecom operators, with or without participation of the regulatory authority, should get together after each congestion event to evaluate network performance and implement remedial measures. But it is important to understand what congestion tells us: it tells us that people are calling their loved ones and that the warnings are being disseminated.
# The experience of the 28th of March does not support the 100/200 meter forbidden zone rule. The evacuation instructions indicated that everyone close to the coast should go beyond 2 km. If the 100/200 meter rule is related to the tsunami, the evacuation order should have asked people to evacuate to a point beyond 100/200 meters as appropriate. The response that will serve the interest of public safety will include:
** Preparing vulnerability maps of the coast for tsunamis and cyclones.
** Establishing effective early warning systems, especially in the areas of greatest vulnerability.
** Ensuring that people have places to evacuate to within 10-15 minutes (this may require the building of structures for vertical evacuation such as the tsunami hills proposed by Professor Hettige of the University of Colombo).
** Moving structures with significant externality effects such as roads, electricity transformers and telecom towers out of the areas of greatest vulnerability. Once the information is publicly available, the affected citizens and other parties such as insurance companies will use that information to make the appropriate decisions.
# An authoritative, adequately resourced single-focus agency responsible for all aspects of disaster warning is essential. See above.


  1. In item 2 above, I state that there was no alternative to issuing a warning on the 28th of March. However, we must be cognizant of the cost of warnings (item 7). The stories emerging from the experience of the 28th of March are educative in this regard: http://www.sbpost.ie/post/pages/p/story.aspx-qqqid=3663-qqqx=1.asp.

  2. Luxman Siriwardena

    With regard to the 100/200 meter buffer zone what are the lessons to be learnt from the 28th warning?
    Does it matter whether you are living within 100, 200 or 300 meters when it comes to reacting to the warning?
    Has the Nannies of this Nanny State who direct us, the babes, to give up our land within 100/200 meters, ran away from their own Palaces located within 100 meters from the sea?

  3. Luxman, if the nannies did not ran from their own places (well within 100m!) that proves only one thing: either they are too brave or too stupid!

    I don’t think we’ve had enough tsunamis to depend too much on historical data. Just because the last tsunami did not hit Colombo, it does not mean that the next one wouldn’t! So if anyone neglects the warning, they do it on their own risk!

  4. Okay, now there is a better place to express your opinion on the Buffer Zone. BBC news.bbc.co.uk/sinhala has started a pool.

    When I checked last, the results were as follows:

    Agree for a buffer zone: 58%
    Don’t agree: 38%
    Suggest consulting affected 4%

    Luxman, any comments?

  5. Wow, what a discovery. This is a good way of solving the LTTE problem too. Forget facts; forget best practice; forget benefit-cost analysis; just register your vote on the Internet. This is true democracy, enabled by ICTs. We don’t need Parliament; we don’t need policy debate or research, just an Internet poll will do.

    The fact that this is not a representative sample should not bother us; after all everyone has access to the Internet in Sri Lanka.

  6. The 100 m issue is a political one. That has nothing to do with an Early warning System. There is no rule that a tsunami waves will stop exactly at 100m. So as far as the Early warning system is concerned, it is irrespective whether people live within the 100m belt or not. In any case, the warning should be there.

    One party wants to chase off everyone from this belt so that they can sell the land to robber barons. The other party objects to it because it is the ‘popular demand’, and they assume they can get some more votes by doing so. Other than that, I do not see any logic both in implementing a 100m zone or objecting it.

    Should we waste time discussing irrelevant political issues? I guess not.

  7. Luxman Siriwardena


    BBC or any other survey should get the views of the affected or likely to be affected. It is very easy for the academics, socalled educated, experts, and politicians who believe in Nanny States to ask others to adhere to the ditates by them.
    In the final analysis these self-centred fellows have deprived the poor resuming their life in terms of their vocation, shanties or social life.Just think Chanuka if you and your children are asked to not to return to your place of residence as you are within 100mt and your neibours who live in 101mts continue with their life, including schooling for kids.


    Any way do no worry Cha, this Nanny state will definetly work in LTTE areas where enforcement will through the barrel of the gun. Chanuka , Please advise them whether it should be 100, 200mts as our Nanny say or 500mts as theirs say.

  8. Some may recall the U of Ulster research that was reported in Nature last month about the stress increasing in the Sunda Trench. The events of March 28th were easier to understand because of that. Now Nature has published something that’s more positive in tone: a model that can predict a tsunami within 25 minutes of an earthquake. The report is at http://news.xinhuanet.com/english/2005-04/11/content_2812603.htm