[8] A separate, unrelated magnitude 7.3 earthquake occurred off the coast of the North Island of New Zealand, approximately 900 km to the south, several hours before the main quakes.

[10] The Kermadec-Tonga subduction zone runs east of the Kermadec Islands and marks the boundary between the Australian and Pacific plates.

[15] On 28 July 2021, nearly 5 months after the Kermadec Islands mainshock, an 8.2 magnitude earthquake struck the Alaska Peninsula,[16] and another 8.1 magnitude earthquake struck the Sub-Antarctic British territory of the South Sandwich Islands on 12 August of that year.

The largest slide was at Pills Beach, where about 400 metres of coastal cliffs collapsed, leaving a column of sediment in the ocean.

[23] The main quake led to tsunami warnings being issued around the Pacific, as far away as Peru, but particularly for the North Island of New Zealand.

[25] NEMA said the first waves were due to reach New Zealand at around 9:49 am local time, with flooding expected along areas of the East and West Coasts of the North Island, and issued an evacuation order for areas of Northland, Bay of Plenty, Gisborne, and Great Barrier Island.