WELLINGTON, New Zealand — 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.
Residents recorded videos of small wave surges in some places, including at Tokomaru Bay near Gisborne. In the afternoon, the National Emergency Management Agency said the threat had passed and people could return to their homes, although they should continue avoiding beaches
The Pacific Tsunami Warning Center said ocean gauges had measured tsunami waves of 30 centimeters (1 foot) in Vanuatu and said waves of similar size could cross the Pacific to Latin American coasts.
The largest quake struck about 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.
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.”
The U.S. Geological Survey said it was centered near the remote Kermadec Islands at a depth of 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 13 miles under the ocean about 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.