2004 Tsunami - Lessons from Thailand for the future of building design

Southern Thailand was regarded as a non-seismic-prone region, therefore buildings were not designed for earthquakes, let alone tsunamis. The survival of many non-seismic, non-tsunami resistant buildings shows that it is possible to design buildings to resist moderate tsunamis, with important implications to saving lives (Pictures attached)

These results will be presented at the 2nd Asia Conference on Earthquake Engineering "Seismic Hazards and Damage Mitigation in the Asian Region" held in Manila, Philippines from March 10-11, 2006.

For pictures and full details of the findings, please download the paper attached and/or contact the authors. For more information on ACEE 2006, please contact Prof Andres Oreta at [email protected]

Authors: P. Lukkunaprasit and A. Ruangrassamee

The Indian Ocean tsunami on December 26, 2004 caused an unprecedented catastrophe in the region. Historical records prior to the event had shown that in the past century there had been 7 tsunamis in the Indian ocean, none of which developed into a destructive tsunami, except the one in 1883 which was caused by volcanic eruption of Krakatoa and killed many people in Indonesia (International Research Institute for Climate Prediction 2005). The scarcity in occurrences of tsunamis in the region resulted in unawareness and un-preparedness of the public for the hazard.

The earthquake, triggered by the India plate subducting into the Burma plate, caused the sea bed to rise by several meters. As a consequence, tsunamis of 5-12 m in height were generated along the coasts of southern Thailand. More than 5,300 people were killed, and about 3,000 people were missing in Thailand (Department of Disaster Prevention and Mitigation 2005). The total fatalities may exceed 250,000 in the region, the worst caused by a tsunami in recorded history.

A reconnaissance team from Chulalongkorn University was dispatched to the tsunami stricken areas. This paper presents observations on damages of buildings hit by the tsunami in southern Thailand. Lessons learned from the observations are imperative to the future building design and construction especially for evacuation shelters.

The southern Thailand has been regarded as a non-seismic-prone region, therefore buildings have not been designed for earthquakes, not to mention tsunamis. Low-rise residential and commercial reinforced concrete (RC) buildings, which form the bulk of the building stock, are generally constructed without supervision of engineers.

It is interesting to note that, except for buildings of quite poor quality, the majority of reinforced concrete structures (2-3 stories commercial/residential buildings) survived with minor to moderate damage in wave heights of 3-6 m. from the ground surface. This observation is encouraging because it suggests that it is possible to design buildings to resist tsunamis of moderate heights with reparability or even functional performance level. The latter is essential for evacuation shelters.

The following lessons are learned from the catastrophic event:
1. Lack of historical records of disaster should not rule out the possibility of occurrence of such event if the governing factors for the given hazard exist.
2. The survival of a large number of non-seismic, non-tsunami resistant buildings in Thailand does point out that it is possible to design buildings to resist tsunamis of moderate heights with reparability performance.
3. Erosion from incoming as well as receding waves needs to be considered in the design of retaining structures, embankments, and foundations.
4. The excellent performance of infill masonry panels with openings suggests that openings in the walls should be beneficial in reducing the impact of the waves.