Seismic Activity Near Kokopo, Papua New Guinea

The region surrounding Kokopo on the island of New Britain experiences frequent strong earthquakes due to its position along active tectonic boundaries. Multiple plates converge here, including segments of the Pacific and Australian plates, producing both shallow crustal events and deeper subduction-related seismicity. Depths exceeding 300 km, such as the 385.5 km recorded for the 7 July 2013 magnitude 7.3 event, reflect the steep descent of the subducting slab beneath the Bismarck Sea.

On 7 July 2013 at 18:35 UTC, a magnitude 7.3 earthquake struck 190 km east-northeast of Kokopo. Its great focal depth limited surface damage despite the large magnitude. This event forms part of a documented sequence of major earthquakes in the immediate area since 2000. Four events of magnitude 7.0 or greater have occurred within roughly 100 km of one another during this period.

The sequence began with a magnitude 7.0 earthquake on 29 October 2000, located 191 km east-southeast of Kokopo. Five years later, on 9 September 2005, a magnitude 7.6 event occurred 135 km east of the city. The 7 July 2013 magnitude 7.3 shock followed, and the most recent large event was a magnitude 7.9 earthquake on 17 December 2016, centered 140 km east of Kokopo. These four earthquakes illustrate persistent strain release along the same segment of the plate boundary.

Geological mapping of New Britain shows a complex arrangement of thrust faults, strike-slip structures, and volcanic arcs. The 2013 event’s depth places it well within the subducting slab, consistent with intermediate-depth seismicity observed throughout the western Pacific. Historical records indicate similar deep earthquakes have occurred in the region for decades, underscoring the long-term stability of the subduction geometry.

Continued monitoring by regional seismic networks remains essential. The proximity of these large events to populated centers on New Britain highlights the importance of building codes and tsunami preparedness, even when great focal depths reduce the likelihood of strong ground shaking at the surface.

References

USGS Earthquake Catalog data for events near Kokopo, Papua New Guinea (provided prompt parameters).