8/22/2005
SCIENCE ALERT BULLETIN: WIZ-05/02
4 pm Monday, 22 August 2005
White Island crater lake update
The crater lake, which started to form in the active crater at White Island in August 2003, is now only 1 m below overflow level. Seepage is occurring from the lake onto the floor of the Main Crater and the barrier holding back the lake is eroding.
In October 2004, the lake rose to within 3.9 m of overflow before rapidly dropping 1.7 m (possibly due to an underground leak), stabilising at 5.5 m below overflow. The lake level has since resumed rising, and is now only 1 m below overflow (see plot below). The lake is expected to continue rising until overflow occurs.
The lake is currently contained by a barrier of softer material on the northeast side. This barrier has eroded back 9-13 metres since November 2004 and is now only 10.5 m wide. It is expected to erode further as the water level rises. Seepage from the lake has increased the flow of water in the streams that drain the Main Crater floor. Much of this area has become waterlogged and access is difficult and dangerous.
If the lake continues to rise at the current rate it is expected to overflow before the barrier erodes away. The overflow could occur as soon as the next 6-8 weeks, but will be dependent on factors like rainfall, volcanic fluid input, temperature and leakage. Once the lake starts to overflow the amount of water in the streams will increase significantly. This is the largest lake to have formed within the active crater and has drowned the formerly active vents.
The Alert Level for White Island remains at Alert Level 1, there is no significant change in volcanic activity on the island.
Brad Scott
Volcano Surveillance Co-ordinator
For photographs of the lake see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For further volcano information see http://www.geonet.org.nz
4 pm Monday, 22 August 2005
White Island crater lake update
The crater lake, which started to form in the active crater at White Island in August 2003, is now only 1 m below overflow level. Seepage is occurring from the lake onto the floor of the Main Crater and the barrier holding back the lake is eroding.
In October 2004, the lake rose to within 3.9 m of overflow before rapidly dropping 1.7 m (possibly due to an underground leak), stabilising at 5.5 m below overflow. The lake level has since resumed rising, and is now only 1 m below overflow (see plot below). The lake is expected to continue rising until overflow occurs.
The lake is currently contained by a barrier of softer material on the northeast side. This barrier has eroded back 9-13 metres since November 2004 and is now only 10.5 m wide. It is expected to erode further as the water level rises. Seepage from the lake has increased the flow of water in the streams that drain the Main Crater floor. Much of this area has become waterlogged and access is difficult and dangerous.
If the lake continues to rise at the current rate it is expected to overflow before the barrier erodes away. The overflow could occur as soon as the next 6-8 weeks, but will be dependent on factors like rainfall, volcanic fluid input, temperature and leakage. Once the lake starts to overflow the amount of water in the streams will increase significantly. This is the largest lake to have formed within the active crater and has drowned the formerly active vents.
The Alert Level for White Island remains at Alert Level 1, there is no significant change in volcanic activity on the island.
Brad Scott
Volcano Surveillance Co-ordinator
For photographs of the lake see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For further volcano information see http://www.geonet.org.nz
SCIENCE ALERT BULLETIN: RUA-05/01
2.00 pm Monday, 22 August 2005
Ruapehu Volcano update: Crater Lake temperature increasesRecent Crater Lake visits have recorded a rise in the temperature of the lake. On August 4 the temperature was 23.3°C, and on August 21 it had risen to 32.3°C.
Volcanic tremor recommenced at Ruapehu during July, and continues at varying levels. Volcanic tremor is not unusual at Ruapehu, but this is the strongest since August 2004.
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Ruapehu Crater Lake will often warm following periods of volcanic tremor, and the present observations are following that trend. Heating cycles are common at Ruapehu, occurring every 9-12 months and lasting 1-3months. As the lake warms, steam plumes may be observed under favourable conditions.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Brad Scott
Volcano Surveillance Co-ordinator
2.00 pm Monday, 22 August 2005
Ruapehu Volcano update: Crater Lake temperature increasesRecent Crater Lake visits have recorded a rise in the temperature of the lake. On August 4 the temperature was 23.3°C, and on August 21 it had risen to 32.3°C.
Volcanic tremor recommenced at Ruapehu during July, and continues at varying levels. Volcanic tremor is not unusual at Ruapehu, but this is the strongest since August 2004.
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Ruapehu Crater Lake will often warm following periods of volcanic tremor, and the present observations are following that trend. Heating cycles are common at Ruapehu, occurring every 9-12 months and lasting 1-3months. As the lake warms, steam plumes may be observed under favourable conditions.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Brad Scott
Volcano Surveillance Co-ordinator
5/17/2005
SCIENCE ALERT BULLETIN: WIZ-05/01
3 pm Tuesday, 17 May 2005
White Island crater lake update
The crater lake, which started to form in the active crater at White Island in August 2003, is now only 3.3 m from overflow level. Considerable seepage is occurring from the lake onto the Main Crater floor and the barrier holding back the lake is eroding.
In October 2004 the lake rose to within 3.9 m of overflow, before rapidly dropping 1.7 m, (possibly due to an underground leak) stabilising at 5.5 m below overflow. The lake level has since resumed rising, and in early May reached 3.3 m below overflow (see plot below). The lake is expected to continue rising through winter with continued rainfall.
The lake is currently being held in by a barrier of softer material on the northeast side. This barrier has eroded back 7-8 metres since November 2004 and is now only 15 m wide. It is expected to erode further as the water level rises. Seepage from the lake has increased the flow of water in the streams that drain the Main Crater floor. Much of this area has become waterlogged and access is difficult and dangerous.
This is the largest lake to have formed within the active crater and has drowned the formerly active vents. Future eruptions will occur through the crater lake ejecting moderate volumes of water that may flood down the Main Crater floor towards the sea. This is a significant change in the nature of volcanic hazards on the island.
There is no significant change in volcanic activity on the island; hence the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
For photographs of the lake see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For further volcano information see http://www.geonet.org.nz
3 pm Tuesday, 17 May 2005
White Island crater lake update
The crater lake, which started to form in the active crater at White Island in August 2003, is now only 3.3 m from overflow level. Considerable seepage is occurring from the lake onto the Main Crater floor and the barrier holding back the lake is eroding.
In October 2004 the lake rose to within 3.9 m of overflow, before rapidly dropping 1.7 m, (possibly due to an underground leak) stabilising at 5.5 m below overflow. The lake level has since resumed rising, and in early May reached 3.3 m below overflow (see plot below). The lake is expected to continue rising through winter with continued rainfall.
The lake is currently being held in by a barrier of softer material on the northeast side. This barrier has eroded back 7-8 metres since November 2004 and is now only 15 m wide. It is expected to erode further as the water level rises. Seepage from the lake has increased the flow of water in the streams that drain the Main Crater floor. Much of this area has become waterlogged and access is difficult and dangerous.
This is the largest lake to have formed within the active crater and has drowned the formerly active vents. Future eruptions will occur through the crater lake ejecting moderate volumes of water that may flood down the Main Crater floor towards the sea. This is a significant change in the nature of volcanic hazards on the island.
There is no significant change in volcanic activity on the island; hence the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
For photographs of the lake see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For further volcano information see http://www.geonet.org.nz
11/15/2004
SCIENCE ALERT BULLETIN: RUA-04/01
2.00 pm Monday, 15 November 2004
Ruapehu Volcano update: Volcanic tremor signals and Crater LakeModerate volcanic tremor recommenced at Ruapehu on November 3, and continues at varying levels. Volcanic tremor is not unusual at Ruapehu, but this is the strongest since April–May 2003. Since March 2004 the lake temperature has fallen from a high of 35°C, to below 16°C by August. The Crater Lake was visited on November 13 and the temperature had risen to 18.9°C, the first sign of an increase since August. A slight increase in the area of grey discoloured water over the active vents was also observed, suggesting convection is occurring but the lake is not fully mixed.
Ruapehu Crater Lake will often warm following periods of volcanic tremor, and the present observations are following that trend. Heating cycles are common at Ruapehu, occurring every 9-12 months and lasting 3-4months. As the lake warms, steam plumes may be observed under favourable conditions.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Brad Scott
Volcano Surveillance Co-ordinator
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htmFor further information on volcano monitoring see http://www.geonet.org.nz/aboutvolcanoes.html
2.00 pm Monday, 15 November 2004
Ruapehu Volcano update: Volcanic tremor signals and Crater LakeModerate volcanic tremor recommenced at Ruapehu on November 3, and continues at varying levels. Volcanic tremor is not unusual at Ruapehu, but this is the strongest since April–May 2003. Since March 2004 the lake temperature has fallen from a high of 35°C, to below 16°C by August. The Crater Lake was visited on November 13 and the temperature had risen to 18.9°C, the first sign of an increase since August. A slight increase in the area of grey discoloured water over the active vents was also observed, suggesting convection is occurring but the lake is not fully mixed.
Ruapehu Crater Lake will often warm following periods of volcanic tremor, and the present observations are following that trend. Heating cycles are common at Ruapehu, occurring every 9-12 months and lasting 3-4months. As the lake warms, steam plumes may be observed under favourable conditions.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Brad Scott
Volcano Surveillance Co-ordinator
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htmFor further information on volcano monitoring see http://www.geonet.org.nz/aboutvolcanoes.html
8/7/2003
SCIENCE ALERT BULLETIN: WIZ-03/01
2 pm Thursday, 7 August 2003.
Changed hazards at White Island due to a large crater lake.
Over the last few months a substantial lake has formed in the active crater at White Island. This is the largest lake to have formed within this crater and has recently drowned the active vents. As a consequence future eruptions will occur through the crater lake and, if ejected by eruptions, moderate volumes of water could flood down the Main Crater floor towards the sea. This is a significant change in the nature of volcanic hazards on the island.
Over the last 10-15 years many small ponds and lakelets have formed in topographic lows or the floors of small sub-craters within the 1978/90 Crater Complex. Their life has often been short as they have been in filled by the next eruption, or drained as new vents have formed. The small volumes of these lakes, was such that they had no influence on eruptive activity. However, the current lake volume is large enough that it will influence the next phase of eruptive activity from the volcano and result in a new hazard to people visiting the island. Ejection of the lake in an eruption could cause flooding of the shallow stream valleys across the Main Crater floor, maybe as far as the sea. This would occur along with the already existing hazards caused by rock and ash fall during explosive eruptions.
Should there be no significant eruptive activity within the next 18-24 month period and the lake continues to fill, it may reach overflow level. In this situation water may overflow into drainage channels on Peg 12 Flat, to the south of 1978/90 Crater Complex and these channels may further erode if water is continuously flowing in them. It is our intention to establish a monitoring programme to accurately measure the level of the lake or its rate of rise.
There is no significant change in volcanic activity on the island; hence the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For an explanation of the alert levels see http://www.gns.cri.nz/what/earthact/volcanoes/alertl_1.html
2 pm Thursday, 7 August 2003.
Changed hazards at White Island due to a large crater lake.
Over the last few months a substantial lake has formed in the active crater at White Island. This is the largest lake to have formed within this crater and has recently drowned the active vents. As a consequence future eruptions will occur through the crater lake and, if ejected by eruptions, moderate volumes of water could flood down the Main Crater floor towards the sea. This is a significant change in the nature of volcanic hazards on the island.
Over the last 10-15 years many small ponds and lakelets have formed in topographic lows or the floors of small sub-craters within the 1978/90 Crater Complex. Their life has often been short as they have been in filled by the next eruption, or drained as new vents have formed. The small volumes of these lakes, was such that they had no influence on eruptive activity. However, the current lake volume is large enough that it will influence the next phase of eruptive activity from the volcano and result in a new hazard to people visiting the island. Ejection of the lake in an eruption could cause flooding of the shallow stream valleys across the Main Crater floor, maybe as far as the sea. This would occur along with the already existing hazards caused by rock and ash fall during explosive eruptions.
Should there be no significant eruptive activity within the next 18-24 month period and the lake continues to fill, it may reach overflow level. In this situation water may overflow into drainage channels on Peg 12 Flat, to the south of 1978/90 Crater Complex and these channels may further erode if water is continuously flowing in them. It is our intention to establish a monitoring programme to accurately measure the level of the lake or its rate of rise.
There is no significant change in volcanic activity on the island; hence the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/what/earthact/volcanoes/bulletins.html
For an explanation of the alert levels see http://www.gns.cri.nz/what/earthact/volcanoes/alertl_1.html
5/26/2003
SCIENCE ALERT BULLETIN: RUA-01/2003
11.30 am Monday, 26 May 2003.
Ruapehu Volcano update:
Steam plumes, volcanic tremor and Crater Lake temperatures
Since the middle of March 2003 the temperature of Ruapehu’s summit Crater Lake has been slowly rising, and is now slightly over 40oC. Similar temperatures were observed in January 2003 when the lake temperature reached 42oC.
This morning around 10.00 am a steam plume was observed above the Crater Lake, rising 2-300m. No seismic activity accompanied this plume, suggesting there was no eruption and that the plume was generated by atmospheric conditions alone. Steam plumes were also observed on April 21.
Ruapehu Crater Lake has been visited three times recently to record the lake temperature and collect water samples. The lake temperature has risen from 30oC on March 5 to reach 41.6oC on May 15. During this time there has been an increase in the background levels of volcanic tremor and some volcanic earthquakes have also been recorded. There have been no significant changes observed in the lake water chemistry.
This is the fourth time that the temperature of the Crater Lake has risen above 35oC since the start of 2001. It is not unusual for the temperature of the Crater Lake to cycle over periods of 6-9 months. Minor hydrothermal activity can occur in the lake during the temperature peaks.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htm
Brad Scott
Volcano Surveillance Co-ordinator
11.30 am Monday, 26 May 2003.
Ruapehu Volcano update:
Steam plumes, volcanic tremor and Crater Lake temperatures
Since the middle of March 2003 the temperature of Ruapehu’s summit Crater Lake has been slowly rising, and is now slightly over 40oC. Similar temperatures were observed in January 2003 when the lake temperature reached 42oC.
This morning around 10.00 am a steam plume was observed above the Crater Lake, rising 2-300m. No seismic activity accompanied this plume, suggesting there was no eruption and that the plume was generated by atmospheric conditions alone. Steam plumes were also observed on April 21.
Ruapehu Crater Lake has been visited three times recently to record the lake temperature and collect water samples. The lake temperature has risen from 30oC on March 5 to reach 41.6oC on May 15. During this time there has been an increase in the background levels of volcanic tremor and some volcanic earthquakes have also been recorded. There have been no significant changes observed in the lake water chemistry.
This is the fourth time that the temperature of the Crater Lake has risen above 35oC since the start of 2001. It is not unusual for the temperature of the Crater Lake to cycle over periods of 6-9 months. Minor hydrothermal activity can occur in the lake during the temperature peaks.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htm
Brad Scott
Volcano Surveillance Co-ordinator
12/9/2002
SCIENCE ALERT BULLETIN: WIZ-02/01
2.30 pm Monday, 9 December 2002
White Island Volcano update: Volcanic tremor signals
Since November 21 weak volcanic tremor has been recorded at White Island. The level has fluctuated since that time, being stronger today. The volcanic tremor todate, has been accompanied by booming sounds, shockwaves in the steam plume above the active vent and some ejection of small ballistic blocks about the active vent. A surveillance visit was made last week, but activity was milder than the tour operators were reporting. Fumarole temperatures ranged from 97.5 to 147.7°C, all being similar to measured values over the last few months.
The emission from the active vent was not particularly vigorous during our visit, and is certainly well below that seen over the last couple of years. Small explosions were occurring and shock waves could be seen in the steam plume. Some ballistic blocks lay around the active vent, there being no sign of ash emission.
However there is a significant area of heating occurring to the east of the active vent and into the lake on the crater floor. Fumarole fields like this can precede crater formation, which is often an explosive process. Past activity indicates that significantly larger eruptions, some ejecting large rocks well beyond the active vent, could occur with little or no warning. Such larger eruptions would pose a significant hazard to anyone on the island at the time.
Caution should be exercised when visiting the island now that background activity is increasing.
As there is no significant change in activity the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
2.30 pm Monday, 9 December 2002
White Island Volcano update: Volcanic tremor signals
Since November 21 weak volcanic tremor has been recorded at White Island. The level has fluctuated since that time, being stronger today. The volcanic tremor todate, has been accompanied by booming sounds, shockwaves in the steam plume above the active vent and some ejection of small ballistic blocks about the active vent. A surveillance visit was made last week, but activity was milder than the tour operators were reporting. Fumarole temperatures ranged from 97.5 to 147.7°C, all being similar to measured values over the last few months.
The emission from the active vent was not particularly vigorous during our visit, and is certainly well below that seen over the last couple of years. Small explosions were occurring and shock waves could be seen in the steam plume. Some ballistic blocks lay around the active vent, there being no sign of ash emission.
However there is a significant area of heating occurring to the east of the active vent and into the lake on the crater floor. Fumarole fields like this can precede crater formation, which is often an explosive process. Past activity indicates that significantly larger eruptions, some ejecting large rocks well beyond the active vent, could occur with little or no warning. Such larger eruptions would pose a significant hazard to anyone on the island at the time.
Caution should be exercised when visiting the island now that background activity is increasing.
As there is no significant change in activity the Alert Level for White Island remains at Alert Level 1.
Brad Scott
Volcano Surveillance Coordinator
10/8/2002
SCIENCE ALERT BULLETIN: RUA-02/03
3.00 pm Tuesday, 8 October 2002 .
Ruapehu Volcano update: Volcanic tremor signals and Crater Lake
Since September 6 there have been five short-lived episodes of moderate-strong volcanic tremor at Ruapehu. This has been followed by generally higher than normal background levels since September 22. The duration of these episodes have ranged from 8 hours to more than 2 days (see plot below). Several volcanic tremor episodes have been recorded this year (see RUA-02/02), all having similar characteristics to the recent activity.
Ruapehu Crater Lake has been visited twice recently, both recording a lake temperature around 19°C. The lake temperature has been below 20°C since mid June 2002. There have been no changes observed in the lake water chemistry or any reports of any changes at Crater Lake.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Plot of volcanic tremor amplitudes for 10 September to 8 October 2002.
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htm
Peter McGinty
Duty Volcanologist
3.00 pm Tuesday, 8 October 2002 .
Ruapehu Volcano update: Volcanic tremor signals and Crater Lake
Since September 6 there have been five short-lived episodes of moderate-strong volcanic tremor at Ruapehu. This has been followed by generally higher than normal background levels since September 22. The duration of these episodes have ranged from 8 hours to more than 2 days (see plot below). Several volcanic tremor episodes have been recorded this year (see RUA-02/02), all having similar characteristics to the recent activity.
Ruapehu Crater Lake has been visited twice recently, both recording a lake temperature around 19°C. The lake temperature has been below 20°C since mid June 2002. There have been no changes observed in the lake water chemistry or any reports of any changes at Crater Lake.
As there is no change in activity the Alert Level for Ruapehu remains at Alert Level 1.
Plot of volcanic tremor amplitudes for 10 September to 8 October 2002.
For further volcano status information see http://www.geonet.org.nz
For previous Science Alert Bulletins see http://www.gns.cri.nz/earthact/volcanoes/status.html
For an explanation of the alert levels see http://www.gns.cri.nz/earthact/volcanoes/alertl_2.htm
Peter McGinty
Duty Volcanologist
