Graham Leonard: New Zealand's B-list volcanoes

New Zealand's volcanoes are world renowned, and most Kiwis are familiar with our big ones such as Ruapehu, Taranaki and Tarawera. But what about our lesser talked about volcanoes? GNS Science principal scientist Graham Leonard joins Susie to chat about some of the volcanic areas around the country that people are less familiar with - from Northland's periodically active field to volcanoes buried in the Canterbury plains gravels.