Civil Defence alert: No tsunami threat after 8.2 Alaska earthquake

The Pacific Tsunami Warning Centre said "widespread hazardous tsunami waves are possible". Image / NWS Tsunami Alerts

Civil Defence has confirmed there is no tsunami threat to New Zealand after an 8.2 magnitude earthquake struck Alaska on Thursday evening.

"Based on current information, the initial assessment is that the earthquake is unlikely to have caused a tsunami that will pose a threat to New Zealand," the National Emergency Management Agency (Civil Defence) said.

"New Zealand coastal areas may experience strong and unusual currents and unpredictable surges at the shore [on Friday]."

Earlier on Thursday evening, Civil Defence was assessing a tsunami risk to New Zealand after an 8.2 earthquake struck off the Alaska Peninsula at 6.16pm, at a depth of 17km.

There is no tsunami threat to New Zealand following the M8.1 ALASKA PENINSULA earthquake. Based on current information, the initial assessment is that the earthquake is unlikely to have caused a tsunami that will pose a threat to New Zealand.

— National Emergency Management Agency (@NZcivildefence) July 29, 2021

New Zealand coastal areas may experience strong and unusual currents and unpredictable surges at the shore tomorrow. Be cautious if you are at the beach or on the water.

— National Emergency Management Agency (@NZcivildefence) July 29, 2021

Thu Jul 29 06:23:22 UTC 2021 event picture pic.twitter.com/UQwlRCmRlk

— NWS Tsunami Alerts (@NWS_NTWC) July 29, 2021

The Pacific Tsunami Warning Centre (PTWC) confirmed the tsunami threat from an 8.2 magnitude earthquake off the peninsula had passed.

We are assessing whether the M8.1 ALASKA PENINSULA earthquake poses any tsunami threat to New Zealand. If a tsunami has been generated it is not likely to arrive in New Zealand for at least 12 hours hours.

— National Emergency Management Agency (@NZcivildefence) July 29, 2021

Civil Defence said people do not need to evacuate unless directly advised by local civil defence authorities.

"If a tsunami has been generated in this location it is not likely to arrive in New Zealand for at least 12 hours."

#Tsunami sirens sound in Kodiak, Alaska after a major magnitude 8.2 earthquake struck off the coast; risk being evaluated for the Pacific pic.twitter.com/2yPJpEuuqF

— Watchman (@Judmir3) July 29, 2021

Two other earthquakes with preliminary magnitudes of 6.2 and 5.6 occurred in the same area within a half-hour of the first one, the US Geological Survey reported.

PTWC had issued warnings for Hawaii and Guam but they were subsequently lifted.

PTWC said some coastal regions near the Alaska Peninsula would remain under a Tsunami warning.

According to Honolulu Star Advertiser, The Pacific Tsunami Warning Center listed the magnitude as 8.1 and said "an investigation is underway to determine if there is a tsunami threat to Hawaii". But the U.S. Geological Survey said the quake was magnitude 8.2 and hit 56 miles (91 kilometres) east southeast of Perryville, Alaska.

Thu Jul 29 07:42:22 UTC 2021 event picture pic.twitter.com/8Lj3kVBU8Q

— NWS Tsunami Alerts (@NWS_NTWC) July 29, 2021

"Based on all available data a tsunami may have been generated by this earthquake that could be destructive on coastal areas even far from the epicentre," PTWC said.

Based on the preliminary seismic data, the quake should have been widely felt by almost everyone in the area of the epicentre. It might have caused light to moderate damage.

Moderate shaking probably occurred in Perryville, Chignik Lake and Sandpoint.

-Additional reporting AP