Published on : Friday, March 5, 2021
New Zealand has been hit by three powerful earthquakes, prompting some evacuations and triggering tsunami warnings across the South Pacific. An offshore 7.3 magnitude quake left many people awake during the night throughout New Zealand. Another massive 8.1 earthquake occurred within hours of the first in the Kermadec islands region, around 1,000 km from New Zealand. Nearly 107 minutes prior to the 8.1-quake, a 7.4 magnitude quake had hit 50km west. The proximity and the timing of the 7.4 magnitude earthquake have indicated to be the foreshock of the largest earthquake. According to reports by US Geological Survey, the 8.1 magnitude earthquake near the Kermadec Islands, New Zealand was the result of reverse faulting in the Tonga-Kermadec subduction zone.
The location, depth and style of the faulting pointed its occurrence on or near the west-dipping subducting plate interface between the Pacific and Australia plates. It also said that in terms of seismic moment, the 8.1 magnitude earthquake was 11 times larger than the foreshocks. It was also informed that the change induced by 7.3 oblique reverse faulting earthquakes does not signify any relation with the 7.4-foreshocks or 8.1-earthquake. The US Geological Survey said the larger quake was centred in the remote Kermadec Islands at a depth of 19 kilometers and the earlier quake was centred at a depth of 21 kilometers under the ocean about 174 kilometers northeast of the city of Gisborne. The earlier quake was more widely felt in New Zealand, and residents in the major cities of Auckland, Wellington and Christchurch reported being shaken awake.
Officials in New Zealand also issued a tsunami warning for coastal areas after the smaller earthquake struck off its northeastern coast at about 3AM (local time) Friday. While both quakes triggered warning systems, there were no immediate reports of serious damage or casualties and the warning was later lifted just before the larger quake struck. Civil defense authorities in New Zealand informed people in certain areas on the East Coast of the North Island on Friday morning that they should move immediately to higher ground and not stay in their homes. They said a damaging tsunami was possible. The US Tsunami Warning System also cautioned that the larger quake could cause tsunami waves of between 1 to 3 metres in French Polynesia and waves of up to 1 metre in Niue, New Caledonia and the Solomon Islands.
The earthquake is considered to be the largest of the century as the previous earthquake with a magnitude of 8 had hit the area in January 1976, which occurred more than 10km to the north. In 2011, a magnitude 6.3 quake hit the city of Christchurch, killing 185 people and destroying much of its downtown. Although no casualties or damage have been reported so far, Emergency Management Minister Kiri Allan had asked the residents to evacuate and warned them that the danger can prevail throughout the afternoon.
The National Emergency Management Agency of New Zealand cancelled the advisory that was issued following the earthquake and mentioned that as per the GNS Science, the beach and marine threats have now passed for all areas based on ocean observation. However, the agency has said that strong and unusual currents and unpredictable surges will continue for up to another 24 hours and people should remain vigilant and also asked people to take precautions with respect to beach and ocean activities.