Hawke's Bay advised to be prepared for eruptions
NASA says this image shows Mount Tongariro as it appeared at 12:55 a.m. New Zealand time on August 7, 2012. The image was acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP.
Civil Defence is advising Hawke's Bay people to be prepared for possible further eruptions and ash fall from Mount Tongariro.
Agencies including Police, Fire, Ambulance, District Health Board, Unison and Civil Defence met on Friday and have agreed to a plan should the current state on Mount Tongariro escalate.
GNS has advised more eruptions are possible, but the impact on Hawke's Bay is likely to be ash fall to a depth of 2-3 millimetres. While this sounds minimal, any amount of ash fall can have an impact, as volcanic ash is toxic.
HBCDEM Group Manager Ian Macdonald says ash fall can aggravate respiratory conditions, getting into the eyes and mouth. It can create discomfort for pets and be poisonous to stock. Volcanic ash is also abrasive and can affect outdoor mechanical and electronic equipment.
"We encourage people to consider how ash fall might affect them and take action now so that they are prepared," says Ian Macdonald.
Volcanologists hope that today they will have a clearer idea of what caused last Monday's Mt Tongariro eruption, and how likely it is to explode again.
Mike Rosenberg, of GNS Science, said many of the pieces of the puzzle - ash and gas samples, analysis of the earthquakes which preceded the eruption and visual descriptions of it - would be brought together today and put before experts.
``I'm hoping that today there will be some consensus and a clear and consistent message about what's caused the eruption and what's likely to happen in the future.''
Advice on how to prepare for volcanic ash fall can be found at the Hawke's Bay CDEM website - www.hbemergency.govt.nz.
Farmers and horticulturalists should be familiar with information on the Ministry for Primary Industries website http://www.mpi.govt.nz, MPI's Adverse Event Volcanic Impact document, and consider how ash fall could impact their operations.
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Aug 13 2012, 2:50 pm - Tongariro Volcano
Volcanic Alert Bulletin TON-2012/18 - Update and volcanic ashfall prediction; Volcanic Alert is at Level 2; Aviation Colour Code is Yellow
Volcanic activity remains low. There has been no significant seismic activity at Tongariro for several days. Heavy rain on Sunday produced minor lahars which affected State Highway 46. No further reports have been received since Sunday. Of the three eruption scenarios deemed possible over the next seven days, the scenario considered most likely is that there will be no further eruptions, the next likely is that any eruptive activity will be of similar magnitude to that on August 6, and the least likely that larger eruptions will occur.
Seismic activity at Tongariro has remained low since the August 6 eruption. No ground deformation originating in the Tongariro area has been observed. Recent poor weather has prevented visual observations.
Scientists have considered three eruption scenarios deemed possible over the next seven days and have evaluated these based on monitoring data, historic activity at Tongariro, and experience of New Zealand and overseas eruptions. Over the next seven days the scenario considered most likely is that there will be no further eruptions. The next most likely scenario is that any eruptions will be of similar size to the eruption on August 6. The scenario considered least likely is that larger eruptions will occur. This assessment is valid for only the next seven days and a change in monitoring parameters may change the assessment.
On Sunday heavy rain remobilised some ash erupted on August 6 and a minor lahar crossed State Highway 46 at the northern foot of Tongariro. No further reports of lahar flows have been received since Sunday.
Some concerns remain over the debris flow formed by the August 6 eruption that is blocking two small streams draining the northern slopes of Tongariro and the potential this has to produce larger lahars. A process is in place to start to assess this threat.
Analyses of volcanic gases from airborne measurements last Thursday have been completed and showed 3,900 tonnes per day of carbon dioxide (CO2) and 364 tonnes per day of hydrogen sulphide (H2S) gas, in addition to the 2,100 tonnes per day of sulphur dioxide (SO2) reported previously. These gases confirm the presence of magma beneath the volcano, but do not give any indication about its depth or volume.
The smell of hydrogen sulphide (H2S) gas was reported from several localities south of Tongariro over the weekend. High hydrogen sulphide (H2S) gas levels have been observed in the volcanic plume, and may potentially cause some discomfort for those with breathing difficulties. The areas affected will always be downwind of the volcano, and may change daily.
Several days of microscopic and geochemical analysis of the widespread ash (by Massey, Waikato, Victoria and Otago universities, and GNS Science) shows that there is very little or no new magma in the ejecta of the August 6 eruption. This suggests that the eruption was predominantly gas driven, but the involvement of magma in the future cannot be ruled out.
On Friday scientists collected gas and water samples from Ketetahi hot springs and collected some of the ballistic ejecta from the Ketetahi Hut area to help determine the nature of the erupted products.
Poor weather has prevented any further fieldwork today. Once the weather improves additional gas sampling flights and surface gas sampling will be attempted. Data will also be collected from portable seismographs on Tongariro.
An ashfall prediction plot is attached to this bulletin should a future eruption occur.
Volcanic Alert Level remains at level 2
Aviation Colour Code remains Yellow
Steven Sherburn
Duty Volcanologist
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Pacific quake swarm sparked underwater volcano eruption
Wellington - A swarm of more than 150 earthquakes over two days last month caused a previously dormant volcano to erupt 1,100 metres beneath the Pacific Ocean, a scientist said Monday.
The eruption of the Havre Volcano, about halfway between New Zealand and Tonga, is believed to have caused a 7,500 square kilometer floating island of pumice that was encountered by a New Zealand navy ship last week.Cornel de Ronde, principal scientist of the Institute of Geological and Nuclear Sciences, told Radio New Zealand the source of the pumice had been identified in cooperation with French researchers in Tahiti who monitor earthquakes in the south-west Pacific.
"When they looked at their physical records they saw that on July 17th and 18th, there were some 157 earthquakes of magnitudes between 3.0 and 4.8," he said.
De Ronde said they occurred near the time of the first sighting of the pumice "raft" and when the institute looked at its database it found the Havre volcano which it had previously surveyed.
It was a caldera volcano, like White Island, 50 kilometres off the west coast of New Zealand's North Island, which erupted last week, but the Havre was not thought to have erupted before, he said.
De Ronde said the pumice island was so light that it had floated several hundred kilometres from the volcano when it was encountered by the HMNZS Canterbury, which took samples last week.
Scientists were also analysing samples of rock ejected from Mount Tongariro, on New Zealand's North Island, to try to find out why it erupted a week ago for the first time in 115 years.//DPA
http://www.nationmultimedia.com/breakingnews/Pacific-quake-swarm-sparked-underwater-volcano-eru-30188192.html
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