In the early morning hours of Friday 24 December 2004, a moment magnitude 8.1 earthquake struck a remote area of the southern Tasman Sea.

[3] The earthquake occurred at a shallow depth and had a moment magnitude of 8.1, with its epicentre being located roughly 150 km (93 mi) to the west of the boundary between the Australian and Pacific plates.

[4] It is hypothesised that at the Puysegur Trench, the thicker continental crust of New Zealand is acting as a buttress which impedes the movement of the Australian plate.

This results in the steep angle of subduction observed at the trench, and transfers stresses down into the Macquarie Block farther south, where the ancient fracture zones are pre-existing areas of crustal weakness.

[3] The stress that is imparted into the Macquarie Block is released through the rupture of these weak fracture zones, and this is believed to have been the cause behind this earthquake.

[8] After this event, a large section of the southern end of the Macquarie Block was reactivated, with many smaller earthquakes occurring to the northwest of the plate boundary along one of the fracture zones.

In New Zealand, the shaking was prolonged and was strong enough to wake people up from their sleep at the southern end of the South Island, but no damage was reported.

[2] In Tasmania, local police received a handful of calls after the earthquake, with reports of shaking houses and swinging light fittings.