The locations, depths, and focal mechanism solutions for the October 7th events are all consistent with them resulting from reverse faulting associated with subduction along the Australia-Pacific Plate boundary.

The 7.8 Mw  earthquake of October 7, 2009 (22:18 UTC), occurred about 60 km north, and 15 minutes after, a slightly smaller earthquake with a 7.7 Mw  of the same date Occurred (22:03 UTC).

Due to them occurring in the same region, both events are considered a doublet earthquake.

[8] the largest earthquakes of the aftershock sequence were the aforementioned 7.4 event as well as a magnitude 6.8 tremor on October 8.

[9] On June 3, 2009, an unrelated magnitude 6.3 earthquake struck 38 km west of the capital of Port-Vila, injuring four, damaging a few buildings and triggering landslides.