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Ruapehu heating up 18 September 2008

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Ruahepu Crater Lake (GeoNet image)
Ruapehu Crater Lake (GeoNet image).

GeoNet reports today that Ruapehu appears to be entering a new heating cycle. The Crater Lake temperature has risen to 22°C this month, from 16°C in August, a change accompanied by some volcanic tremor. Between October 2007 and June 2008 the temperature varied between 34°C and 37°C. Sulphur dioxide and carbon dioxide levels in the volcano’s plume are also showing an upwards trend, consistent with the rising temperature within the Crater Lake. There is nothing unusual about any of this, however: ‘Cyclic activity in the Crater Lake’, observes the GeoNet bulletin, ‘is very common at Ruapehu’.

The alert level for Ruapehu remains at level 1 (departure from typical background surface activity, signs of unrest). GeoNet warns that ‘Ruapehu remains an active volcano and future eruptions may occur without warning’.

At the beginning of the week the skiing season at Ruapehu was extended by three weeks because of record snow falls.

For all our New Zealand coverage: New Zealand « The Volcanism Blog.

News
Ruapehu entering new heating cycle – GNSNew Zealand Herald, 18 September 2008

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

The Volcanism Blog

Ruapehu: warning of ‘elevated unrest’ 14 May 2008

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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

The Volcanism Blog

Ruapehu: ‘no imminent threat of eruption’ 6 May 2008

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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 Volcanism Blog

New Zealand: activity intensifies at Ruapehu 2 May 2008

Posted by admin in activity reports, natural hazards, New Zealand, Ruapehu.
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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’.

Ruapehu Crater Lake (GeoNet image)

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 eruptingNew 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

The Volcanism Blog