The earthquake occurred in a five-hundred kilometer wide diffuse plate boundary that accommodates the westerly motion of the Philippine and Caroline plates with respect to the Australian plate.
The preliminary epicenter is situated near the northwest- striking Ransiki fault, one of several major faults that have been identified in northwestern New Guinea. The focal mechanism is consistent with the earthquake occurring as right- lateral slip on a northweststriking fault.
In the past few decades, several earthquakes in this area have caused human casualties. On September 12th, 1979 a magnitude 7.9 earthquake struck about 190 km to the east killing 15 people. Damage estimates for this quake ranged from $5 to $25 million. Another quake with a magnitude of 6.3 occurred 330 km to the southeast on September 9th, 1985, and killed at least 10 people. Most recently, a magnitude 6.3 quake, that injured 28 people, occurred 190 km to the east on November 20th 1994.