September 8, 2002 Earthquake: Kairiru Is, Muschu Is, Wewak, Papua New Guinea

Reference #1053:

Four people killed and at least 70 injured on Kairiru and Muschu Islands and in the Wewak area. At least 500 dwellings destroyed and 200 damaged, water tanks, pipelines and a bridge damaged on the islands and in the Maprik-Suain-Wewak area. A local tsunami with an estimated maximum wave height of 1.5 meters damaged some buildings in the area. Landslides occurred and new hot springs appeared on Kairiru Island. Muschu and Kairiru Islands uplifted approximately one half meter. Felt (III) at Jayapura, Indonesia.

Reference #11914:

The magnitude 7.8 (Ms) "Wewak Earthquake" of 9 September 2002 was one of the largest earthquakes ever recorded from the northwestern part of mainland Papua New Guinea. The earthquake was shallow and its epicenter was located at 3.2S, 142.9E, just off-shore and about 90 km west-northwest of Wewak. The strong shaking caused serious damage to numerous houses and water tanks, triggered many landslides and created ground cracks. The collapse of buildings during the strong shaking caused the death of four people and injuries to many others. Uplift of as much as 30-40 cm occurred at the "Wewak Islands", Tarawai, Walis, Kerasau, Kairiru and Muschu. A moderate tsunami, having maximum amplitude of 3-4 m, was generated at the same time as, or soon after, the earthquake. The focal mechanism of the earthquake may have involved both overthrusting and strike-slip movements, but dominantly the former. The wide separation of the hypocentre and the location of the centroid of the moment tensor solution suggests a large rupture surface. This finding is supported by the great extension (about 180 km) of the aftershock distribution field. The predominantly overthrust focal mechanism for the main earthquake and the approximately east-west orientation of the aftershock distribution :field are consistent with the main pattern of faulting in the east-west trending coastal mountain ranges. Two large aftershocks (magnitude 6) about one week after the main earthquake were located at the western end of the aftershock distribution field. Their normal faulting mechanisms and their locations suggest movement on a northeast trending cross-fault system which terminates the main east-west overthrust (and transcurrent) rupture surface. The tectonic significance of the September 2002 "Wewak Earthquake" is that it represents a major overthrust movement of the leading edge of the India-Australia Plate, contributing to the long history of uplift of the coastal region of northwestern Papua New Guinea.

Four people were killed and many were injured during the earthquake shaking. The main cause of deaths and injuries was trauma from collapsing houses.

Damage to houses and water tanks was common between the epicentral area and Wewak Town, and probably greatest near the mouth of the Hawain River. Many houses in the villages in the neighbourhood of Wewak, mostly made of bush materials, sustained damage. Many semi-permanent builclings were also damaged and water tanks broken. Houses and water tanks in other towns such as Maprik also sustained damage. Similar damage was reported from the islands Tarawai, Walis, Kerasau, Yuo, Kairiru and Muschu. Damage by the earthquake did not extend to Aitape and Sissano Lagoon.

In all 873 houses were damaged, some beyond repair. Numerous water tanks were damaged some beyond repair. In addition, a number of bridges and the Wewak Wharf sustained damage. Electricity and water supplies to Wewak Town were also disrupted. Most of the damage occurred at Wewak and immediate neighbourhood, and was related to the earthquake and not the tsunami. The two major aftershocks on the nights of 16 and 17 September caused damage to property in the Aitape area, especially at Yakamul, Pual and Nuku.

2002, September 8, 18:44:25.53 UTC. 3.260 South, 142.940 East, depth 13.0 km, 7.6 Mw HRV. (reference #9910)