Seismology
The earthquake occurred at 6:49pm local time (UTC+10) along the boundary of the Australia and the Pacific tetonic plates at 2°58′S 141°55′E / 2.96°S 141.92°E / -2.96; 141.92. The tsunami was originally thought to have been caused by a two-metre vertical drop in the Pacific Plate along a 40 km (25 mi) long crack, caused by the earthquake. Later work suggested that in fact a massive underwater landslide had occurred.
The tsunami raised awareness among scientists of the potential for small earthquakes to trigger large tsunamis, if they cause undersea landslides. It is now recognised that such events can be very dangerous, as the earthquake may be too small to be felt on land, or detected by the Pacific Tsunami Warning Center. Any resulting tsunami can thus appear without warning.
Read more about this topic: 1998 Papua New Guinea Earthquake