The 2004 Nabire Earthquake and Seismic Activity in Papua, Indonesia

On 26 November 2004 at 02:25 local time, a magnitude 7.1 earthquake struck 29 km south-southwest of Nabire, Papua, Indonesia, at a shallow depth of 10 km. This event formed part of an intense seismic sequence in early 2004 that highlighted the region's persistent tectonic instability.

Papua occupies a complex plate-boundary zone where the Australian Plate converges with the Pacific Plate and several smaller microplates. This interaction produces thrust faulting, strike-slip motion, and rapid crustal deformation along the island of New Guinea. Nabire lies near the southern margin of the Weyland Thrust and adjacent to the Tarera-Aiduna Fault system, both of which accommodate significant strain. Historical records show repeated moderate-to-large earthquakes in this corridor, consistent with ongoing convergence rates exceeding 10 cm per year in places.

The November 2004 mainshock was preceded by two other strong events within weeks: a magnitude 7.0 earthquake on 5 February located 28 km south of Nabire and a magnitude 7.3 event on 7 February near the south coast of Papua. A second magnitude 7.1 shock occurred the same day as the Nabire event, centered 68 km away. All four earthquakes clustered within a 70 km radius, illustrating how stress transfer can trigger multiple ruptures along neighboring fault segments in rapid succession.

Shallow focal depths, such as the 10 km recorded for the November mainshock, increase the potential for strong ground shaking in populated coastal areas. The geology of the region—characterized by young sedimentary basins, limestone karst, and steep topography—amplifies landslide and liquefaction hazards during such events. Long-term monitoring by regional seismic networks continues to document aftershock sequences and background seismicity that reflect the same plate-boundary processes active in 2004.

References

USGS Earthquake Catalog (event data 2004)
Global CMT Project focal mechanism solutions
Tectonic framework studies of western New Guinea (peer-reviewed literature)