One of the biggest earthquakes to hit the South Pacific in modern history forced thousands of people in New Zealand to evacuate and triggered tsunami warnings across the world Friday, but it did not appear to cause injuries or major damage because it struck in remote ocean.
The magnitude 8.1 quake was the largest in a series of tremors that hit the region over several hours, including two earlier quakes that registered magnitude 7.4 and magnitude 7.3.
The earthquakes triggered warning systems and caused traffic jams and some chaos in New Zealand as people scrambled to get to higher ground, but their remoteness meant they did not appear to pose a widespread threat to lives or infrastructure.
The largest quake struck about 1,000 kilometers (620 miles) off the coast of New Zealand. One of the earlier quakes hit much closer to New Zealand and awoke many people as they felt a long, rumbling shaking.
“Hope everyone is ok out there,” New Zealand Prime Minister Jacinda Ardern wrote on Facebook during the night.
After the largest quake, civil defense authorities in New Zealand told people in some coastal areas to immediately get to higher ground. They said a damaging tsunami was possible, and waves could reach up to 3 meters (10 feet).
Emergency Management Minister Kiri Allan told reporters that people had followed the advisory.
“They felt the long or strong earthquakes and they knew to grab their bag and head into the highlands,” she said. “I can only thank and acknowledge the tireless efforts of the men and women from up and down the coast who knew how to act, when to act, and what to do.”
She warned that the threat could remain throughout much of the afternoon and people should not return home until authorities gave the all-clear. Allan said evacuations took precedence over coronavirus distancing measures.
The U.S. Geological Survey said it was centered near the remote Kermadec Islands at a depth of 19 kilometers (12 miles).
The agency said in a report that the quake occurred at the intersection of the Pacific and Australia tectonic plates and eclipsed the largest quake previously recorded in the region, a magnitude 8.0 in 1976.
It said the interaction between the plates creates one of the most seismically active regions in the world, and it has recorded 215 quakes there above magnitude 6.0 over the past century.
Jennifer Eccles, an earthquake expert at the University of Auckland, said the quake was at the top end of the scale for those involving only the Earth’s ocean crust.
“This is about as big as it gets,” she said.
She said most quakes larger than magnitude 8.0 tend to occur when a section of more robust continental crust is involved.
The U.S. Geological Survey said the magnitude 7.4 quake was likely a “foreshock” that contributed to the larger quake but that the first quake that hit closer to New Zealand was too far away in time and distance to have directly contributed.
Officials in New Zealand had hours earlier issued a tsunami warning for coastal areas after the first quake struck off its northeastern coast at about 2:30 a.m. Friday. There were no immediate reports of serious damage or casualties, and the warning was lifted just before the largest quake hit.
The U.S. Geological Survey said the first quake was centered at a depth of 21 kilometers (13 miles) under the ocean about 174 kilometers (108 miles) northeast of the city of Gisborne.
It was widely felt in New Zealand, and residents in the major cities of Auckland, Wellington and Christchurch reported being shaken awake.
In 2011, a magnitude 6.3 quake hit the city of Christchurch, killing 185 people and destroying much of its downtown.