One of the women behind the Pike River Families campaign says the public support continues to surprise her.

Cantabrians are being encouraged to show their support for the families at a peaceful protest this afternoon.

Sonya Rockhouse, who lost her son Ben in the blast six years ago, said she can't understand why so many people are standing with them.

She said the families have been overwhelmed by the public support.

"We've obviously touched a nerve or touched a chord somewhere, and it's wonderful, it's just amazing," she said.

"Everyday it's like a big groundswell, it's just picking up momentum."

Rockhouse said she thought the movement would last two weeks, but says the support is continuing more than three months later.

The protest gets underway on Sir William Pickering Drive at 4pm.