On July 17, 1998, a tsunami hit the northern coast of Papua New Guinea (PNG), destroying 3 entire villages, damaging 4 more and killing 2000 people. Tsunamis—unexpected, often devastating waves that are usually caused by earthquakes—happen quite often, but are usually not large enough to cause damage.
An earthquake did occur about 15 minutes before the PNG tsunami, but many believe that the quake was not strong enough to cause the 50 foot waves of the tsunami. Also, the waves took longer than expected to reach shore after the earthquake. So what caused the tsunami?
After much investigation and some controversy, researchers now believe that the earthquake caused an underwater landslide—specifically, a rotational landslide or slump—about 40 miles off the coast of PNG. This landslide was what produced the tsunami.
This animation shows a bird’s eye view of the formation of the tsunami and its movement as it hit ground in Papua New Guinea. Generated using a computer model created by Stephan Grilli of the University of Rhode Island, the simulation matches actual data about the height and effects of the tsunami.
Grilli’s computer model can be used to help identify tsunami danger zones and to map evacuation routes out of those areas.
For more information about this research, see "Tsunami Warning".