An investigation of earthquake
hazard in Papua New Guinea (PNG) by a
yearly extreme magnitude method using
the magnitude 7 earthquake record
since 1900 shows that the Bougain-
ville Island seismic zone is by far
the most active, followed by the New
Britain and northern mainland PNG
regions. Return period for magnitude
7.0 earthquakes occurring in
normalized 10,000km2 areas of the
Bougainville Island, New Britain,
Huon, West Bismarck, North Sepik and
Ramu seismic zones is 37, 60, 81, 88,
125 and 125 years respectively. These
areas are much more active than the
California Seismic Zone 4 region
including the San Andreas Fault,
which has a normalized magnitude 7.0
return period of 299 years, calcul-
ated here by the same method.
Only southern PNG, including
the Papuan Fold Belt and most of the
Bismarck Sea, are less active than
California Zone 4. The Papuan Fold
Belt is only marginally less active
than California Zone 4, but more
active than the State of California
taken as a whole.