As the ash fades from a blackened northern face of Mt Tongariro, White Island has been conducting its own fireworks show.

GNS scientist Brad Scott last night confirmed the island off the Whakatane coast - the tip of a massive submarine volcano - had been continually erupting since Sunday night, its first eruption since 2001.

Ash had been hitting two cameras mounted on the island, although the eruption had been small and scientists had detected no signs of escalation, he said.

Scientists are also closely monitoring Mt Tongariro, where steam was billowing from at least three new vents created in Monday's late-night eruption.


Mr Scott said it was possible there might be more such cracks but low cloud had so far hampered aerial flights to view the full area.

A sulphuric smell had been noticed as far south as Wellington, although air quality monitoring did not raise any health concerns.

It remained unclear whether Mt Tongariro would blow again over the coming days, Mr Scott said.

"We've just got to watch this space."