Police have launched a fresh appeal for information in their search for a 14-year-old girl who went missing in northern Tasmania more than a week ago.

Shyanne-Lee Tatnell was last seen in the vicinity of Henry Street near the North Esk River in Launceston around 8.30pm on Sunday, April 30.

She was on her way to visit a friend but failed to arrive.

Tasmania Police on Monday renewed calls for anyone in the area at the time, including drivers with dash cam footage, to come forward.

"There is nothing to suggest foul play at the moment but we're investigating every avenue ... to make sure we're not missing anything," Inspector Craig Fox told reporters.

"We don't have any specific information that it is anything other than missing, but we've got some serious concerns around the safety of Shyanne."

The Westpac Rescue Helicopter and police divers searched the area in the days after her disappearance but found no sign of her.

Her grandmother Michelle Hubbard told the ABC on Friday Shyanne-Lee was constantly on her phone and it was very unusual she hadn't made contact.

Ms Hubbard said the teenager was lovely but not very street savvy.

"She's very trusting, probably too trusting of people," Ms Hubbard said.

Shyanne-Lee is approximately 160cm tall, with a slim build and blond hair. She was last seen wearing a cream, hooded jumper.

She moved to Launceston recently and had been staying in youth accommodation.