Factor: Quality of buildings

The general level of damage is determined not only by the height and depth of penetration but also by the structural quality of the buildings and their distance from the shore. Whereas simple wooden structures sometimes collapsed even when the water only reached moderate heights, the large hotel buildings showed no signs of serious structural damage.

There were only isolated cases of reinforced concrete columns being damaged by floating debris or the foundations being washed away. In most cases, loadbearing structures were not damaged, and none of the larger hotels collapsed — although this does not preclude the possibility of a constructive total loss in exceptional cases.

Even if the thin brick or concrete partition walls in hotel complexes collapsed, as they did everywhere, the main buildings in particular stood up to the tsunami quite well.

Damage

The catalogue of damage to smaller bungalows was dominated by the collapse of partition walls. Most of the relatively thin reinforced concrete columns remained intact, however, and only collapsed in regions where the flood waters attained a high rate of flow.

Nevertheless, most of the bungalows that were exposed to high water levels had to be regarded as total losses because their partition walls and non-structural elements were completely destroyed.

Some apartment blocks in large complexes in Khao Lak were flooded up to the first floor. The rooms presented a chaotic picture.

In focus

Wooden structures like bars and outside restaurants, which were near the beach in many hotel complexes, were carried away by the water so that the foundations were left exposed. Such simple structures were badly damaged even in regions with lower flood heights of no more than 1.5 m.

However, it only took a few weeks to replace them because of their light wooden construction. In the case of larger buildings with their longitudinal axis aligned to the flow of water, the front ends of these structures absorbed the brunt of the tsunami.

Partition walls and even wooden structures in the rear of these buildings were hardly damaged at all. A similar situation was observed with office buildings in streets running perpendicular to the shore. Businesses further inland that were not directly impacted by the full force of the wave only suffered damage to the decor and water damage, whereas the walls and even some display windows stayed intact.

The tsunami also destroyed hundreds of cars and boats. Numerous boats were washed several hundred metres inland and badly damaged in the process.

Cars were carried away by the floods and many of them were demolished beyond recognition. Cars that show no visible signs of serious damage but were saturated by sea water must be regarded as a total write-off because of the effects of corrosion.