Yesterday, search and rescue teams shifted their efforts to Woodhill Forest near Muriwai Beach on Auckland's west coast.
Senior Sergeant Paul Newman said officers had spoken with several of Avison's friends, family members, colleagues and people she had recently had contact with to establish a clearer picture of her movements.
He said police did not believe foul play was involved.
"However, we are concerned for Carissa's safety, as her actions are out of character."
Police also made an appeal to Avison.
"If she is aware of the search, we ask Carissa to make contact with police or family and let us know she is well."