August 19, 1977 Tsunami: Sunda Islands, Indonesia

1977 August 19. A catastrophic earthquake shook Sumbawa Island. It covered an extensive area from the southern coast of Indonesia to the northwestern coast of Australia. A large tsunami was produced. The first press reports announced waves 30 m high in Indonesia and 8 m high in Australia Apparently, these figures were exaggerated. A group from the International Tsunami Information Center visited the coastal regions of Sumba, Sumbawa, Lombok and Bali Islands to assess the destruction and wave run-ups, and to obtain other detailed information from local people. Inaccessible areas on the southern coast of Sumba and Sumbawa islands were photographed from the air. Information was processed that had been gathered by the Indonesian military, search and rescue parties, provincial administration, and by medical teams visiting accessible areas in the coastal villages to offer help and assess the extent of loss of property and life. These records were supplemented by radio broadcast accounts from individual settlements.

The southern coasts of the islands, with the exception of Bali, is sparsely populated. Villages are generally small and scattered. Hence the loss of human life was not high. According to incomplete data, over 180 people killed and 3,900 left homeless. Fishing boats and equipment were lost. For a large part of the Indonesian territory, which had sustained heavy damage from the tsunami, no information is available on the height of the rise in the water level. However, in the accessible region of Sumbawa Island, preliminary information reported that the tsunami reached a height of at least 15 m above the high-tide mark and inundated the island up to 500 m inland.

According to eyewitness accounts, the tsunamis appeared on the Indonesian coast about an hour or two after high tide, beginning with an ebb, which soon left a 100-200 m wide drained belt. This was followed by three large waves with a period of about 5 min or less. The first wave was the highest and most ferocious. Several witnesses noted the duration of agitation of the sea although most made no mention of it. An unusual phenomenon occurred during the time interval between the earthquake and the arrival of the tsunami. Residents of villages in the Sumbawa and Lombok Islands thrice heard a sound at intervals estimated from a few seconds to 1 min and more. It was diversely described as sounding like a bomb explosion or a sonic boom. The sound reportedly emanated from the epicentral area. Nearly every village reported that the water became black and some reported a rise in temperature and an unpleasant smell. The tsunami reached a height of more than 10 m along the coast of Sumbawa. The main destruction was observed on the Sumbawa and Lombok islands.

The tsunami was also observed on the northern and western coasts of Australia. It was reported that on-the Australian coast, as on the Indonesian coast, three waves appeared, the first being the largest. Agitation of the sea continued for several hours. In Dampier the wave reached a height of 2 m; in Port Sampson it varied from 2 to 4 m; in Cape Leveque it reached 6 m. The arrival of the tsunami coincided with an observable ebb and a low tide in many places. These factors weakened the overall effect of the tsunami. Evidently, no lives were lost in Australia although there was one report of a person drawn into the sea by waves.

(above from ref #417)

At least 100 people killed, 89 reported missing, 75 injured. Most casualties and damage were caused by the tsunami. (ref #1053)

$1.2 m damage, 185 killed (ref #1250)

On an inaccessible section of Sumbawa Is, a preliminary study indicates that the waves reached at least 15 m above high tide, and penetrated about 500 m inland in some valleys. (ref #9776)

[At Sumbawa Island] 68 people killed and 54 people missing. The combined number of victims from both the earthquake and tsunami in Indonesia was 107 (ref #12806)