Location:

Period:

8 Sep 2002 18:44:23 - 9 Sep 2002 05:46:10 (11 hours 1 minute)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.6; 68 km ESE of Aitape, Papua New Guinea; (8 Sep 2002) (38km from the swarm center)

4 swarms found nearby.

2001

PS20011007.1(23.1km)

7 Oct

5 hours

5 earthquakes

2007

PS20070722.1(166.6km)

22 Jul

4 hours

6 earthquakes

PS20070806.1(183.1km)

5 Aug

15 hours

6 earthquakes

2024

PS20240323.1(112.0km)

23 Mar

7 hours

6 earthquakes

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Seismic Swarm PS20020908.1 Near Wewak, Papua New Guinea

A significant seismic swarm designated PS20020908.1 occurred in Papua New Guinea from 18:44 on 8 September 2002 to 05:46 on 9 September 2002. Centered 59 km northwest of Wewak, the sequence lasted 11 hours and 1 minute and comprised 14 earthquakes. The events clustered at shallow depths around 10–13 km, reflecting rapid stress release along local fault structures.

The swarm began with a magnitude 7.6 mainshock at 18:44:23 on 8 September, followed by a series of aftershocks ranging from magnitude 4.9 to 5.6. Subsequent events included multiple magnitude 5.0–5.2 shocks at consistent 10 km depth, with a notable magnitude 5.6 event at 04:03:28 on 9 September. Activity concluded with a magnitude 5.2 shock at 05:46:10. This pattern illustrates typical swarm behavior, where an initial large rupture triggers prolonged smaller releases without a single dominant aftershock sequence.

Papua New Guinea lies at the complex convergence of the Australian, Pacific, and several smaller plates, including the Caroline and South Bismarck plates. The region experiences frequent seismicity due to subduction along the New Guinea Trench and strike-slip faulting inland. Wewak and nearby Aitape sit within the Sepik Basin, where sedimentary cover overlies active thrust and normal faults. Historical records show elevated activity since at least the early 20th century, with major events often linked to plate-boundary deformation rates exceeding 10 cm per year.

Since 1 January 2000, only one prior swarm had been recorded in the immediate area, occurring in 2001. The 2002 sequence coincided with a magnitude 7.6 earthquake on 8 September located 68 km east-southeast of Aitape and 38 km from the swarm centroid, underscoring the interconnected nature of regional fault systems.

Geological evidence indicates that shallow crustal earthquakes in this zone commonly produce intensities capable of triggering landslides and localized tsunamis along the northern coast. Updated monitoring by regional networks continues to highlight the persistent hazard posed by the plate boundary, with seismic gaps remaining a focus for long-term risk assessment.

References

SeismoSight internal swarm classification records
United States Geological Survey earthquake catalog (2000–2024 updates)