Following the recent 5.4M earthquake in the Bay of Plenty the volcanologists at GeoNet warned that there was a danger of some kind of response from the volcano and suggested that people keep their distance (see our earlier post). The volcano has shown no sign of unusual activity, however, according to today’s cautious new bulletin from GeoNet:

White Island is an active volcano and eruptions can occur at any time without warning. As a consequence of this earthquake sequence the eruption hazard at the island may have increased above the normal levels. However as we have not recorded any significant changes over the last few days, it would appear the volcano is returning to a normal quiescent state. Normal cautions should be applied when visiting the volcano.

The advice seems to be that visits can resume, with the normal precautions. The alert level for White Island remains at 1: ‘there is no significant change in volcanic activity on the island’.

(Picture: Gas plume, White Island. GeoNet image.)

For all our New Zealand coverage: New Zealand << The Volcanism Blog

Information
Global Volcanism Program: White Island - summary information for White Island (0401-04=)
GeoNet - White Island - GeoNet’s information and current activity page for White Island

White Island, situated 48km offshore of North Island in the Bay of Plenty, is formed by the summit of a submarine volcano and is one of New Zealand’s most active volcanic centres. Visitors have been warned by GeoNet to keep away from the island for the next 48-72 hours following a 5.4M earthquake at 09:06 local time today. The epicentre was 10km south-west of White Island, and the depth of the quake was 5km. The earthquake was widely felt around the Bay of Plenty.

‘This morning’s earthquake was a tectonic-type earthquake, and these are common in the outer Bay of Plenty’, says the GeoNet report on the event. ‘There has been no immediate response from the volcano though the large number of aftershocks means that any seismic response may be difficult to see for several hours’. The alert level for White Island remains at level 1.

(Picture: White Island. GeoNet image.)

For all our New Zealand coverage: New Zealand << The Volcanism Blog

Information
Global Volcanism Program: White Island - summary information for White Island (0401-04=)
GeoNet - White Island - GeoNet’s information and current activity page for White Island

News
Scientists warn tourists off White Island volcano - Stuff.co.nz, 13 June 2008
Volcano warning after earthquake - Melbourne Herald-Sun, 13 June 2008
White Island visits suspended following quake - Radio New Zealand, 13 June 2008

GeoNet, a partnership between GNS Science and the Earthquake Commission, is responsible for geohazard monitoring in New Zealand, including keeping a watchful eye on the country’s volcanoes.

The volcano pages at the GeoNet website have just been revised and expanded, and now offer a very clear overview of current activity, a large image gallery, and excellent, clear descriptions of volcano monitoring methods.

The current activity pages are particularly impressive, with descriptions, maps, real-time seismic information and (where available) webcams and pictures for twelve volcanic centres.

The entire site has the great virtues of simplicity and clarity, which are often lacking in the cluttered, clunky and gimmick-laden sites offered by other volcanism authorities (mentioning no names). GeoNet’s is is now one of the clearest and best-organized volcano monitoring sites to be found anywhere.

(Picture: Gas sampling, Ngauruhoe. GeoNet image.)

For all our New Zealand coverage: New Zealand << The Volcanism Blog

In a bulletin issued yesterday, 13 May 2008, New Zealand’s geohazards monitoring organization GeoNet warns that ‘Elevated gas output, high lake temperatures and volcanic tremor continue to indicate elevated unrest at Ruapehu’.

CO² and SO² levels in Ruapehu’s gas plume are both significantly above normal background levels, and a slight increase in the levels of volcanic tremor has continued, with some periods of stronger tremor. The temperature of Crater Lake remains elevated, fluctuating between 34°C and 36.8°C:

Sustained heat from depth is required to keep the temperature this high for this length of time. It is believed that the source of this heat is magma within the volcano conduit. This magma is also producing the higher than normal gas flow and chemical changes. … These observations are consistent with the volcano-hydrothermal system responding to recent eruptions and ongoing interaction with magma in the volcano conduit. The volcano remains in a status of unrest and the possibility of further activity remains at the volcano. If further eruptions occur, they may occur without warning.

The New Zealand Herald quotes GNS Science volcanologist Dr Tony Hurst as saying that on the basis of these signs Ruapehu ’was not likely to erupt this year, but the signs did point to an increased risk of volcanic activity. That could mean steam plumes, gas bubbles and fountains from Crater Lake, he said’. The Herald’s report on Ruapehu is cheerfully categorized as a ’natural disasters story’.

The alert level for Ruapehu remains at level 1 (departure from typical background activity, signs of unrest).

For all our New Zealand coverage: New Zealand << The Volcanism Blog

Information
Global Volcanism Program: Ruapehu - summary information for Ruapehu (0401-10=)
GeoNet volcanoes - volcano information from GeoNet, the organization responsible for volcano monitoring in New Zealand
GeoNet Volcano Alert bulletins - volcanic activity bulletins from GeoNet

News
Restless Ruapehu emits danger signs - NZ Herald, 14 May 2008
Molten rock on the move in NZ volcano - Radio Australia, 13 May 2008
Scientists warn Ruapehu emitting more gas - Stuff.co.nz, 13 May 2008

GNS Science in New Zealand is improving its seismic network around the city of Auckland with the installation of the first of a network of deep seismic recorders in a 250m-deep disused borehole at Riverhead, about 20km north-west of the city of Auckland. At the moment a seismic network of five surface instruments is dedicated to picking up signs of volcanic unrest around the city.

[GeoNet Volcano Network Coordinator Craig Miller] said while the earthquake hazard in Auckland is not high by New Zealand standards, the focus of the recording instruments in Auckland was on small earthquakes that might precede a volcanic eruption. ‘By getting away from human ground noise, a borehole recorder will enable better data to be collected that can be used to give timely warning of a possible future volcanic eruption in Auckland.’

The new deep instrument, shielded from surface noise and more sensitive to small tremors, brings the network to six, and GNS Science plans to install more deep instruments in boreholes around Auckland in the near future.

For all our New Zealand coverage: New Zealand << The Volcanism Blog

Information
Global Volcanism Program: Auckland - summary information for the Auckland volcanic field (0401-02=)

News
New recorder boosts earthquake, volcano warnings - NZ Herald, 11 May 2008
Borehole instrument boosts earthquake monitoring in Auckland - GNS Science press release, 9 May 2008

Radio New Zealand quotes GNS Science volcanologist Craig Miller as saying that there is no imminent threat of eruption at Mount Ruapehu, despite recent increases in activity at the volcano. Meanwhile the New Zealand Department of Conservation continues to warn that ‘an increase in gas output and the internal temperature of the volcano represent an anomalous state of activity’ and that any further eruptions ‘may occur without warning’.

Information
Global Volcanism Program: Ruapehu - summary information for Ruapehu (0401-10=)
GeoNet volcanoes - volcano information from GeoNet, the organization responsible for volcano monitoring in New Zealand
GeoNet Volcano Alert bulletins - volcanic activity bulletins from GeoNet

News
No imminent threat of Ruapehu eruption says volcanologist - Radio New Zealand, 4 May 2008

The New Zealand Department of Conservation issued a statement today, 2 May 2008, warning of increasing activity at Mount Ruapehu, reports The New Zealand Herald (no sign of the statement yet on the DOC media releases page). On 23 April a bulletin from GNS Science warned that the volcano was showing signs of intensified activity, while on 28 April the DOC reported that the volcano was ‘back to normal’ - although they went on to point out that ‘”Normal” for Ruapehu means that it can erupt at any time without warning’.

Above: Ruapehu Crater Lake (GeoNet image).

Ruapehu is one of New Zealand’s most active volcanoes. The latest eruption was on 25 September 2007; other recent eruptions took place in 2006 and 1995-6. Lahars are a particular danger at Ruapehu because of the crater lake which forms, fed by melting snow, between eruptions. Phreatic eruptive activity and the destruction of the tephra dam holding back the lake can produce highly destructive lahars, as most recently (but not fatally) in March 2007. A lahar from Ruapehu was the cause of the worst railway disaster in New Zealand history on Christmas Eve 1953 when it swept along the Whangaehu river valley and severely damaged a railway bridge at Tangiwai. An approaching train could not be stopped in time and plunged into the river: 151 people were killed.

Information
Global Volcanism Program: Ruapehu - summary information for Ruapehu (0401-10=)
GeoNet volcanoes - volcano information from GeoNet, the organization responsible for volcano monitoring in New Zealand
GeoNet Volcano Alert bulletins - volcanic activity bulletins from GeoNet

News
Mt Ruapehu shows signs of erupting - New Zealand Herald, 2 May 2008
Mt Ruapehu showing signs of volcanic activity - tvnz.co.nz, 2 May 2008
Volcanic activity intensified on Mt Ruapehu - Radio New Zealand, 2 May 2008

From Stuff.co.nz comes a report that a New Zealand volcano is currently erupting. About 1000 kilometres north-east of the North Island of New Zealand is the NZ territory of the Kermadec Islands, and the active volcano concerned is located underwater a further 600 kilometres north of them. Monowai, a seamount, which was only confirmed as a volcano in 1977 (after a survey carried out by HMNZS Monowai), has apparently been erupting regularly over recent years and may have collapsed in on itself in May 2002, in a manner similar to Mount St Helens. Most recently the seamount produced a ‘large seismic event’ on 8 February which was recorded by Laboratoire de Geophysique scientists in French Polynesia.

Information
Smithsonian Institution Global Volcanism Program - summary information for Monowai Seamount (0402-05-)
New Zealand American Submarine Ring of Fire 2005 Expedition - investigated submarine volcanoes including Monowai

News
NZ volcano erupting - under water - Stuff.co.nz, 28 March 2008

Exercise Ruaumoko is currently under way in Auckland, New Zealand. The exercise, which began in November 2007, aims to ’test New Zealand’s all-of-nation arrangements for responding to a major disaster resulting from an impending volcanic eruption in Auckland’ and involves 100 local governmental, civil defence, emergency response and other organizations. The main exercise days are on 13 and 14 March 2008.

Exercise Ruaumoko ‘08 web site - main site for information about the exercise
GeoNet - Exercise Ruaumoko - NZ Government geosciences site for the exercise
CDEM Exercises - Exercise Ruaumoko background information - from the NZ Ministry of Civil Defence and Emergency Management

A previously unknown volcano has been discovered in the Auckland volcanic field in the North Island of New Zealand. A team from the government-owned geophysical research company GNS Science and the University of Auckland have been drilling and analyzing core samples as part of an investigation of Auckland’s volcanic past. One of their drill cores revealed the presence of a scoria cone within the Panmure Basin, itself the mouth of a volcano that erupted around 28,000 years ago. Another drill core contained 2.6m of ash apparently erupted from nearby Mount Wellington some 9,200 years ago. From the GNS Science press release, 22 February 2008:

Scientists from both organisations, including Phil Shane, Ian Smith and Paul Augustinus of The University of Auckland, will now analyse the chemistry of the drill cores to determine the date and the source of each eruption. They will also try to determine the age of the scoria cone.

Project leader Graham Leonard, a volcanologist with GNS Science, said finding what appears to be a new volcanic cone inside  Panmure Basin was a very exciting result. 

‘Most of Auckland’s volcanoes have erupted only once, with the possible exception of  Rangitoto. We will now analyse the core to see if Panmure volcano should be added to the list’, Dr Leonard said.

It was also important to learn more about the Mount Wellington eruption, as it appeared to be the second most recent Auckland eruption, behind Rangitoto which erupted about 650 years ago.

The Auckland volcanic field is around 140km³ in extent and encompasses more than 50 maars, tuff rings, small lava shields and scoria cones formed over the past 140,000 years. The most recent eruptive activity, the Rangitoto eruption which formed Rangitoto Island, is believed to have taken place c.1350 AD.

Information
Smithsonian Institution Global Volcanism Program - summary information for the Auckland volcanic field (0401-02=)

News
Geologists find buried volcano inside Panmure Basin - GNS Science press release, 22 February 2008
New Auckland volcano discovered - NZ Herald, 22 February 2008
Buried volcano found in Panmure Basin - tvnz.co.nz, 22 February 2008
Buried volcano found in Panmure Basin - Radio New Zealand News, 22 February 2008