The identification is based on the attributes in her upper hands Ankush and noose. Her lower hands are in Abhaya (protection) mudra and Varada (boon bestowing) mudra.
Here Tripura is sitting in Ardhapadmasana on an inverted lotus, which in turn is supported by a rectangular peetha.
Beautiful form, see the back view.
The patina is dark signifying considerable age. There is some bronze loss as well. The vigraha is about 8.5 cm in height. It is from Tamil Nadu and may date to the sixteenth century.
10 Feb 2020: According to Siddharth, an avid follower of this site, this Vigraha is Bhuvaneshwari and she is Visnu Maya. Quoting Saptasati Chandi, Chapter 11. However, the most widely held view is Bhuvaneshwari, as one of the Mahavidyas, is a personification of Sakthi, the female energy of Siva. I Suspect there are regional variations.