A man who saw what appeared to be a tsunami sparked panic on a beach north of Christchurch on Friday.

Police decided the man’s concerns were genuine, and the apparent sighting at Kairaki Beach was confirmed by fishermen in the area, Senior Sergeant Tony Ellis said.

“With the weather as it is at the moment combined with sea fog and refraction of light at long distances this impression was gained by many people,” he said.

The man convinced people that a tsunami was coming, creating havoc as people tried to leave the area.

There were no tsunami warnings in place.

“We hope that no one was hurt or unduly shaken during the evacuation of the areas,” Ellis said.

Advance warnings of regionally generated tsunamis were received at communication centres in time to advise the public.

However, a tsunami generated by an earthquake off the New Zealand coast would arrive too fast for any system to warn the public, Ministry of Civil Defence and Emergency Management spokesman Vince Cholewa said.

A locally generated tsunami could arrive within 10 minutes.

A strong earthquake, in which it was too difficult to stand, would be the only warning of a local tsunami. People should immediately move from the coast to higher ground, Cholewa said.