Kiwis have been told to remain alert for 'strong and unusual currents and unpredictable surges at the shore'.
A tsunami expert has warned of the risks posed around the water today as Kiwis awake to a fresh national tsunami warning and the first surges arrive on New Zealand shores.
A magnitude 8.8 earthquake struck off the coast of Russia’s Far Eastern Kamchatka coast yesterday, triggering tsunami warnings acrossthe Pacific.
University of Auckland deputy head of civil and environmental engineering Dr Colin Whittaker told the Herald that tsunami waves tended to increase in height and speed once they reach land.
“A tsunami, when it’s in the deep ocean, it’s very fast but it’s not very scary,” he said.
“They travel as fast as jetliners, but they may only be of average height.”
The risk is not as severe for vessels when they are on the open water.
“If you’re sitting in the middle of an ocean in a boat, you go up a bit, down a bit, but it takes you about 10 odd minutes to do that, but you probably don’t notice,” he said.
However, Whittaker said by the time tsunamis reach a harbour, the wave lengths are shorter, but much taller.
“You’ve got much faster flow speeds. You’ve not just got the wave, but the water around it moving very fast.
“You’re starting to talk several metres per second in very shallow water. When a tsunami makes landfall, it’s just like a whole lot of water. Like a river flood.”
Kiwis awoke at 6.30am to an updated tsunami warning of “strong currents and surges” and advising people to “stay away from water”.
“Stay away from beaches, shorelines, harbours, rivers, and estuaries. Do not go sightseeing.”
Video footage released by Geophysical Service of the Russian Academy of Sciences shows the tsunami-hit Severo-Kurilsk on Paramushir island of Russia's northern Kuril islands. Photo / Geophysical Service of the Russian Academy of Sciences, AFP
The tsunami advisory remains in force and was likely to stay in place until midday.
The emergency management agency said people should avoid the shore until official advice otherwise.
“Strong currents and surges can injure and drown people. There is a danger to swimmers, surfers, people fishing, and anyone in or near the water close to shore.
“People in or near the sea in the following areas should move out of the water, off beaches and shore areas and away from harbours, marinas, rivers and estuaries.”
Tsunami activity has already reached parts of New Zealand.
“The first currents and surges are unlikely to be the largest and are expected to continue over many hours.
“The threat must be regarded as real until this advisory is cancelled.”
Beyond New Zealand, the US and Japan have lifted their tsunami warnings, but Chile, Easter Island and Colombia still remain under them, with evacuations currently under way along Chile’s coastline.
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