Abstract
Earthquakes and tsunamis have frequently hit the Indonesian coast. This paper deals with three repeated explosive sounds reported to have accompanied an earthquake in Indonesia on 19 August 1977, and aims to clarify the subsurface source of the sounds, which followed the earthquake and preceeded the arrival of a tsunami on the coast. A model of sound speed distribution for the author's previous hypothesis of acoustic tsunami precursor is applied to provide a more reasonable understanding of such offshore explosive sounds. When a sound is comfirmed to have a subsurface source, it can be taken as a tsunami precursor that comes just after an undersea earthquake. This precursor can be utilized for an urgent tsunami warning in Indonesia.
