A landslide which has created a lake between Wairoa and Gisborne may become a permanent landmark.

The slip has affected 25.8 hectares of land and created a lake about 50 metres deep which is rising about 60cm a day.

It was likely to have been triggered by a small localised earthquake earlier this month and has resulted in about 80 million tonnes of material forming a large dam on the Mangapoike River (a small tributary of the Wairoa River).

Hawke's Bay Civil Defence Emergency Management Group (HBCDEMG) has been working with Wairoa District Council, Gisborne District Council and Hawke's Bay Regional Council to monitor the slip, which is still moving, on the boundary between Wairoa and Gisborne.

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A specialised engineer was at the site on Thursday to assess the situation.

HBCDEMG alternative group controller Iain Maxwell said the engineer's initial assessment found there to be a very low likelihood of catastrophic failure of the landslide.

"At this stage it's looking positive ... it's good news."

However, there was a reasonable probability the landslide and lake would become permanent features, he said.

A more detailed analysis is hoped to be available this afternoon.

Wairoa District Council incident controller Kitea Tipuna said four properties in Wairoa downstream of the site had been made aware of the landslide but no water was leaking from the dam and there was no immediate danger.

People are asked to stay away from the area and not try to view the slip, he said.

Farmers have also been asked to move stock away from the landslide.

On the Wairoa side the only way the site can be accessed is through private property.

Paparatu Rd is closed to the public because of the slip and signs installed.

There is no date for when the road will reopen at this stage.