[31 December 2004]
… written in the immediate aftermath of the disaster.
The footnotes were added somewhat later…

	A view from the hotel grounds looking northwards along the beach. This photo was taken at about 10:05 local time and shows the water at its lowest level. The normal water level can be seen from the contrasting colours on the rocks, and the steeper part of the beach. The men with white shirts on the right of the picture are hotel staff warning people to leave the beach.

Professor Chris Chapman
Scientific Advisor

December 26, Ahungalla, Sri Lanka
9:30am local time (03:30 GMT)
Lillian, my wife, and I were sitting eating breakfast at the beachside Triton Hotel, Ahungalla, Sri Lanka (about 30 km north of Galle). The previous week we had been touring Sri Lanka, ending our trip travelling through Yala National Park and Galle—places we hardly knew of before but images of which are now indelibly imprinted on the world. (Of about 150 staying at the Yala Safari Game Lodge, only 11 survived; the centre of Galle, a UNESCO World Heritage Site, a 16-17th century Portuguese/Dutch fort and port, is essentially gone.) The Triton hotel is a three storey building, well designed by the famous Sri Lankan architect Geoffrey Dawa¹ (see ArchNet Digital Library entries on Geoffrey Dawa and Triton Hotel) and, thankfully, solidly constructed in 1981. As we finished breakfast, the sea slowly rose a few metres to the level of the hotel’s swimming pool and a small wave gently rolled through the pool and hotel lobby.

Mention of a high tide immediately seemed wrong—Lillian and I had been walking on the beach several times and there was essentially no tide and the sea was calm. I said to Lillian, “There must have been an earthquake in the Indian Ocean” but with no previous experience assumed it to be small. Lillian, having suffered 30 years of the English understatement, immediately went and spoke to the manager and warned that worse might be to come and that it was important to get people off the beach. Gently the sea went back to its previous level and the hotel staff began to clean up. But it continued to retreat for the next 20 minutes or so and I began to realize that something big was coming. The sea level was now perhaps 7m below normal¹. Lillian again spoke to the hotel manager who immediately got his staff out with a megaphone advising people to leave the beach. Many people had begun to go down onto the beach out of curiosity.

	A view from the top floor of the hotel 7 minutes later (about 10:12 – relative times are more accurate than absolute times) when the water had reached its highest level. This view is from over the reception area looking seaward across the swimming pool.
	A view from the same location 11 minutes later (about 10:23) as the water rapidly retreated taking the debris of furniture, doors, windows, etc. from the ground floor of the hotel.
	The aftermath later in the afternoon on the ground floor between the reception area and the swimming pool. In the background is the dining room with no windows or furniture left.

10:10am
The big wave came, rising to perhaps 7m above normal¹. Most people in the hotel were already near the stairs and escaped to the higher floors. A few were initially trapped on the ground floor in their rooms and public spaces but were rescued by hotel staff. Girls at the hotel reception were swept through the hotel lobby into the front gardens and survived clinging to palm trees. The ground floor of the hotel was devastated—all windows, doors, furniture, belongings … were gone, swept first inland and then out to sea. Power, water and telephones were immediately cut, of course. No one from the hotel staff or guests was lost, although neighbouring fishing communities cannot have been so lucky—before the wave we had been able to see, in the distance, villagers coming down to the beach to see the retreating sea. Tragically, it would have been impossible to warn them as things happened so fast. An elderly Austrian gentlemen who had been out taking his morning constitutional walk, was swept off the rocks by the first wave and rescued by villagers, was walking back to the hotel and survived clinging to a fence. A few people had minor injuries—mainly cuts and bruises—but nothing life threatening. Those people who were trapped by the wave fared worst.

In the aftermath of the big wave, sea level continued to oscillate for many hours. The peaks were at approximately 09:30, 10:10—the big one, 11:10, 11:50, 12:35, 12:55, etc. local time. The 3rd and 4th surges were larger than the 1st but now seemed insignificant. By afternoon the amplitude of the oscillations had died away even though it was still visible. Only a few people left the hotel as there was an unknown risk of aftershocks. Amazingly, although the kitchens had been destroyed, by lunch-time food and bottled water was rustled up by the hotel staff, and a local doctor attended the injured. As darkness approached we knew that coaches had left Colombo for us but were having difficulty getting through the blocked roads. Another meal appeared, I know not how, and we prepared to spend a long night (darkness comes by 7pm) with some candle light. But the buses arrived at 10pm and the hotel was evacuated, again the hotel providing us all with snack meals and drinks—where from?

Travelling along the darkened roads we were able to see some of the devastation but were still unaware of the true magnitude of the disaster (as was the whole world), and anyway we had to take a circuitous inland route to avoid blocked roads.

1:00am
We arrived at Water’s Edge, a new golf/sports-club/hotel complex on the outskirts of Colombo. Although incomplete, the bar, sports-club and ballroom were open and during the day the manager had procured 200 mattresses, sheets, pillows, towels! The sports-club was useful as it had the only TV in the place showing the ubiquitous CNN. For the next 3 nights the ballroom was our home. Over the next two days everyone moved on to other hotels or to flights home, until on the morning of Wednesday 29th we were the final couple to leave for our scheduled flight home (as we had already confirmed our flight we did not try to alter it), having to endure a rather ponderous welcome by the police (on behalf of the Foreign Office) at Heathrow airport.

Could I have done more? With hindsight I could have been more emphatic about the impending risk and got everyone on to higher floors before the big wave. This would have saved the trauma of the final rush to safety—I didn’t realize how fast I can still run—and would have saved some minor injuries and loss of property on the ground floor, but might have caused panic. But thankfully, no lives were lost. Given the time and distances, there was little we could have done for the neighbouring villages.

Would an early warning system have helped? Of course but the situation is very different from the Pacific: the recurrence rate is very low (there appear to be no recent historical events—locals spoke of a tsunami in their history more than 2000 years ago, although I have been unable to check this². With a recurrence rate longer than a generation, how would people have reacted? We had 40 minutes warning and still did not behave in the most logical fashion); the distances and hence warning times are less than in the Pacific; and some of the countries surrounding the Indian Ocean have fragile infra-structures at best. But given that an early warning system is technically relatively straightforward and inexpensive, of course it should be installed. Perhaps it can be used as a catalyst and driving force for improvements to the local infra-structures rather than just being imposed from outside?

Did the early, small precursor wave occur in all regions? At the time of writing, I have heard no mention of it in the media. I still don’t fully understand what I could have learnt from the 40-45 minute period of the surges³. Is this a function of the earthquake mechanism, or the propagation path? At the time, it was difficult to get my mind around Airy or Jeffreys phases⁴ and the like. Afterwards, I realized I could have deduced roughly the source of the tsunami—if only I’d remembered my PhD thesis from 35 years ago on the Diffraction of Seismic Waves. Between each set of waves there was considerable long-shore drift of the debris, fast enough to roughen the water, south during the ebb and north during the flood, indicating that the waves were being diffracted around the southern coast of Sri Lanka from a source to the SE. And we had only been in the shadow of the island!

We heard interesting stories about animals. An Englishman living with a Sri Lankan family near Matara fled to high ground when an alarm about the approaching wave was raised (they must have had a warning wave as we did). When he arrived, he was surprised to find the cattle, which roam freely, already there. Despite the utter devastation, no dead animals have been found in Yala National Park.

In the West, we tend to think of the Internet as the technology revolution from the end of the 20th century. In countries like Sri Lanka, the revolution has been the mobile (cell) phone, which has altered organizing at the local level beyond belief.

Memories?
Of the extreme generosity and kindness of the Sri Lanka people. Why should 200 foreign tourists in no particular, immediate danger after the main wave, be treated so well? Despite the fact that the hotel staff came from local villages where their personal losses were considerable, many stayed around to rescue and care for us. When we arrived at Water’s Edge, the assistant manager immediately offered his mobile phone to anyone who had not contacted home—the complex was new enough that neither International Direct Dial lines nor Internet had yet been installed. We gratefully rang our daughter (unbeknown to us, Michael Thambynayagam, my manager at Schlumberger Cambridge Research had already contacted her and the Catholic Bishop of Colombo to try to find us). Our guide on our tour of Sri Lanka, Peter Perumal (of Walkers Tours), despite the loss of colleagues and possibly relatives, and preparing for his daughter’s wedding on December 28th, went out of his way to find and visit us at Water’s Edge to check that everything was OK. At the local and individual level, the Sri Lankans are resourceful, well organized and generous people. Unfortunately, the infra-structure is fragile and unable to cope with the wider tragedy. As soon as the country has reconstructed enough to cope, we would urge anyone to visit this beautiful country. We will again.

Notes

1. In earlier drafts of this letter, I gave this figures as 10 m. Looking at my photographs more carefully, I have decided that I was probably guilty of the usual exaggeration of wave heights. This figure, 7m, is probably more accurate.
2. The recent review article by K. Satake, “Tsunamis”, International Handbook of Earthquake and Engineering Seismology, 2002, Chapter 28, 437-451, Academic Press, makes no mention of Indian Ocean tsunamis and the distribution map is only of the Pacific Ocean.
3. Satake, ibid, does not mention this period. Barber, N.F., 1969, Water Waves, Wykeham Publications (London) Ltd. mentions 10 or 20 minutes; Bolt, B.A., 1978, Earthquakes: a primer, W.H. Freeman and Company mentions a period of 15 min for the Hilo, Hawaii 1975 tsunami (p. 79); Bullen, K.E. and Bolt, B.A., 1985, An Introduction to the Theory of Seismology, 4th Ed., Cambridge University Press (p. 465) state “In some cases there are several great waves, separated by intervals of some minutes or more, and the first of these waves is not always the greatest. Frequently, the first great wave is preceded by an extraordinary recession of water from the shore which may commence several minutes or even half an hour beforehand.”, an accurate description of our observations except for the longer period, presumably caused by the earthquake magnitude and mechanism.
4. Jeffreys, H. and Jeffreys, B.S., 1962, Methods of Mathematical Physics, Cambridge University Press describe the dispersion of water waves (Section 17.09 – see equation (21)) but this does not predict such long oscillations (see my theoretical discussion). Presumably this period arises from the large size of the earthquake.

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