Little damage from huge Pacific quake;tsunami threat passes5 March 2021, by Nick Perry

People gather on high ground in Whangarei, NewZealand, as a tsunami warning is issued Friday, March5, 2021. A powerful magnitude 8.1 earthquake struck inthe ocean off the coast of New Zealand promptingthousands of people to evacuate and triggering tsunamiwarnings across the South Pacific. (Mike Dinsdale/NewZealand Herald via AP)

One of the strongest earthquakes to hit the SouthPacific in modern history triggered tsunamiwarnings across the ocean and forced thousandsof people in New Zealand to evacuate coastalareas Friday. Small tsunami waves were seen, butlittle damage was apparent hours later.

The magnitude 8.1 quake in the Kermadec Islandsregion about 1,000 kilometers (620 miles) fromNew Zealand's two main islands was the largest ina series of temblors over several hours, includingtwo earlier quakes that registered magnitude 7.4and magnitude 7.3.

The tsunami threat caused traffic jams and somechaos in New Zealand as people scrambled to getto higher ground.

Residents recorded videos of small wave surges in

some places, including at Tokomaru Bay nearGisborne. In the afternoon, the National EmergencyManagement Agency said the threat had passedand people could return to their homes, althoughthey should continue avoiding beaches.

One of the earlier quakes hit much closer to NewZealand and awoke many people as they felt along, rumbling shaking. "Hope everyone is ok outthere," New Zealand Prime Minister Jacinda Ardernwrote on Facebook during the night.

After the largest quake, civil defense authorities inNew Zealand told people in some coastal areas toimmediately get to higher ground. They said adamaging tsunami was possible, and waves couldreach up to 3 meters (10 feet).

People gather on high ground and check for any sign of atsunami near Whangarei, New Zealand, Friday, March 5,2021. A powerful magnitude 8.1 earthquake struck in theocean off the coast of New Zealand prompting thousandsof people to evacuate and triggering tsunami warningsacross the South Pacific. (Karena Cooper/New ZealandHerald via AP)

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Emergency Management Minister Kiri Allan toldreporters that people had followed the advisory.

"They felt the long or strong earthquakes and theyknew to grab their bag and head into thehighlands," she said. "I can only thank andacknowledge the tireless efforts of the men andwomen from up and down the coast who knew howto act, when to act, and what to do."

The Pacific Tsunami Warning Center cautioned thequake could cause tsunami waves of up to 3meters (10 feet) in Vanuatu and up to 1 meter (3feet) in Tonga, other South Pacific islands and LatinAmerica's Pacific coast.

Chilean authorities ordered people off beaches dueto the potential for a tsunami along the nation's longcoastline. Guatemala issued a tsunami alert, andauthorities in El Salvador ordered people to takeprecautions in recreational activities. Mexico saidthere was no threat.

People walk up a hill above Papamoa Beach, NewZealand, as a tsunami warning is issued Friday, March 5,2021. A powerful earthquake struck in the ocean off thecoast of New Zealand prompting thousands of people toevacuate and triggering tsunami warnings across theSouth Pacific. (George Novak/New Zealand Herald viaAP)

Waves of 30 centimeters (1 foot) above tide levelswere measured by ocean gauges off the Pacific

nation of Vanuatu, off Gisborne, New Zealand, andoff an Australian island. Smaller waves weremeasured elsewhere in the South Pacific.

The U.S. Geological Survey said the strongestquake was centered near the Kermadec Islands ata depth of 19 kilometers (12 miles).

Although the islands are uninhabited, New Zealandhas built research and accommodation facilitiesthere and often had scientists cycling through untilthe coronavirus hit last year and it halted theprogram. But a large group of more than 100people including scientists and students was due tostay on the islands this week, until they were forcedto cancel because of a virus lockdown in Auckland,said a spokesperson from the Department ofConservation.

Traffic slowly works up to high ground at Whangarei,New Zealand, as a tsunami warning is issued Friday,March 5, 2021. A powerful magnitude 8.1 earthquakestruck in the ocean off the coast of New Zealandprompting thousands of people to evacuate andtriggering tsunami warnings across the South Pacific.(Mike Dinsdale/New Zealand Herald via AP)

The USGS said in a report that the quake occurredat the intersection of the Pacific and Australia tectonic plates and eclipsed the largest quakepreviously recorded along the fault line, amagnitude 8.0 in 1976.

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It said the interaction between the plates createsone of the most seismically active regions in theworld, and it has recorded 215 quakes there abovemagnitude 6.0 over the past century.

Jennifer Eccles, an earthquake expert at theUniversity of Auckland, said the quake was at thetop end of the scale for those involving only theEarth's ocean crust.

"This is about as big as it gets," she said.

She said most quakes larger than magnitude 8.0tend to occur when a section of more robustcontinental crust is involved.

The USGS said the magnitude 7.4 quake was likelya "foreshock" that contributed to the larger quakebut that the first quake that hit closer to NewZealand was too far away in time and distance tohave directly contributed.

People watch for signs of a tsunami from a hill abovePapamoa Beach, New Zealand, as a tsunami warning isissued Friday, March 5, 2021. A powerful earthquakestruck in the ocean off the coast of New Zealandprompting thousands of people to evacuate andtriggering tsunami warnings across the South Pacific.(George Novak/New Zealand Herald via AP)

Traffic slowly works up to high ground in Whangarei, NewZealand, as a tsunami warning is issued Friday, March 5,2021. A powerful magnitude 8.1 earthquake struck in theocean off the coast of New Zealand prompting thousandsof people to evacuate and triggering tsunami warningsacross the South Pacific. (Mike Dinsdale/New ZealandHerald via AP)

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John Fitzgerald, left, on holidays with his wife Rita andfriends, scans the horizon from high ground for any signof a tsunami near Waitangi, New Zealand, Friday, March5, 2021. A powerful magnitude 8.1 earthquake struck inthe ocean off the coast of New Zealand promptingthousands of people to evacuate and triggering tsunamiwarnings across the South Pacific. (Peter De Graaf/NewZealand Herald via AP)

A firetruck tells people along the road, through a publicaddress system (PA) to move to higher grounds followinga tsunami warning for American Samoa in Pago Pago,Thursday, March 4, 2021. The Pacific Tsunami WarningCenter cancelled a tsunami watch for Hawaii that wasissued after a huge earthquake occurred in a remotearea between New Zealand and Tonga. The agencypreviously cancelled a tsunami warning it had issued forAmerican Samoa. (AP Photo/Fili Sagapolutele)

Traffic leaves the Port of Pago Pago after closingbecause a tsunami warning was issued for AmericanSamoa on Thursday, March 4, 2021. The PacificTsunami Warning Center cancelled a tsunami watch forHawaii that was issued after a huge earthquake occurredin a remote area between New Zealand and Tonga. Theagency previously cancelled a tsunami warning it hadissued for American Samoa. (AP Photo/Fili Sagapolutele)

The first quake was centered at a depth of 21kilometers (13 miles) under the ocean about 174kilometers (108 miles) northeast of the city ofGisborne.

It was widely felt in New Zealand, and residents inthe major cities of Auckland, Wellington andChristchurch reported being shaken awake.

In 2011, a magnitude 6.3 quake hit the city ofChristchurch, killing 185 people and destroyingmuch of its downtown.

© 2021 The Associated Press. All rights reserved.This material may not be published, broadcast,rewritten or redistributed without permission.

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APA citation: Little damage from huge Pacific quake; tsunami threat passes (2021, March 5) retrieved 25October 2021 from https://phys.org/news/2021-03-huge-pacific-quake-tsunami-threat.html

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