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Steam rises from Mount Tongariro. - Source: Nick and Lottie Bradford
White Island crater, August 6 2012 - Source: GNS Science -
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Volcanic activity at Mount Tongariro has remained weak overnight but White Island is still emitting a plume of steam, gas and ash.
GNS Duty Volcanologist Michael Rosenberg says the activity from Tongariro Volcano remained weak overnight, following its eruption last Monday night.
Earthquakes have been recorded by GeoNet seismometers around the mountain, but seismicity in the local Tongariro area has remained low.
The Te Maari vents are not visible from the north at this time due to low cloud, but the view from the Ngauruhoe webcam does not show any significant plume, Rosenberg said this morning.
No field work is planned for today. Tests have revealed that magma is bubbling high inside Mount Tongariro, which could suggest a larger eruption is imminent, it was reported yesterday.
A series of samples have been tested since the volcano's Te Mari crater erupted on Monday night.
White Island
Meanwhile, on the other side of the North Island in the Bay if Plenty, overnight activity at White Island has remained at similar levels to yesterday, Rosenberg said.
Volcanic tremor remains weak and a low altitude plume of steam,
gas and minor
ash is being emitted from the volcano which erupted on Tuesday
night.
During the past few days the plume colour has been changing between pale grey and white as the ash content varies.
Visitors to White Island are now at a high level of risk, particularly when approaching the active crater, GNS warns. Explosive eruptions can occur at any time with little or no warning.
Additional hazards to visitors to the island include the health effects of volcanic ash and acid gas exposure, including respiratory issues, skin and eye sensitivity to acid gases.
"We advise a high level of caution should be taken, if visiting the island," Rosenberg said.
GNS continues to monitor the volcano. White Island lies 48 kilometres off the Bay of Plenty coast.
The alert level was raised to a Volcanic Alert Level 2 after a surveillance camera captured a small eruption from White Island's crater on Sunday.
Raft of pumice
A navy ship sailing towards the Kermadec Islands, meanwhile, has encountered a 25,000 square kilometre area of pumice pieces.
The area of floating pumice was estimated to be 250 nautical miles in length and 30 nautical miles wide.
The Royal New Zealand Air Force (RNZAF) Orion spotted the phenomenon on Thursday afternoon, while on maritime patrol from Samoa to New Zealand.
The area of floating pumice is about 85 nautical miles West South-West of Raoul Island.
RNZAF staff had been briefed by GNS Volcanologist Helen Bostock the previous day when the ship first encountered an area of pumice from an undersea volcano, believed to be New Zealand's third erupting volcano - the undersea Mount Monowai.
The Commanding Officer, Commander Sean Stewart changed course to intercept the pumice, and brought the ship to a halt to enable retrieval of samples.
The samples will be analysed to determine which volcano they came from.