The Aitape 1998 tsunami: Reconstructing the event from interviews and field mapping

On the evening of 17 July 1998, on the Aitape Coast of Papua New Guinea, a strongly felt earthquake was followed some 10-25 minutes later by a destructive tsunami. The tsunami comprised three waves, each estimated to be about 4 m high. The second of the three waves rose to a height of 10-15 m above sea level after it had crossed the shoreline and caused most damage. Maximum wave heights and the greatest damage were recorded along a 14-km sector of coast centered on Sissano Lagoon. In this sector the wavefronts moved from east to west along the coast; all structures were destroyed, and in the two main villages 20-40 percent of the population was killed. Partial destruction extended 23 km to the southeast and 8 km to the northwest, and effects of the tsunami were felt as far as 250 km to the west-northwest, beyond the international border. More than 1600 people are known to have died, with some estimates as high as 2200; 1000 were seriously injured, and 10,000 survivors were displaced. This paper presents information from interviews with eye-witnesses and from mapping of damage and inundation, and includes new information on the height, shape and timing of the waves; on the possible escape of petroleum and other gases from beneath the seafloor before and during the tsunami; on unusual sound effects that preceded the waves, and lighting effects that followed; on possible deep circulation (to 250 m) of sea water in the waves; on subsidence of the order of 50-70 cm at the coastal sand barrier; and on the resilience and potential protective capacity of certain species of trees. Eye-witness accounts indicate that the tsunami reached the shore at between 09:00 and 09:08 UT, which is earlier than is proposed in published models of the timing and location of the source of the tsunami.