Manaro volcano (Lake Vui), Ambae Island, Vanuatu: eruption update
The eruption at Manaro volcano continues at low levels with mainly phreatic activity. A cone is building up inside the lake forming a small island inside the lake. There are two active vents, one of which ejects water, rocks and mud and the other is producing a tall column of steam and gas (up to 8-10,000 feet). A group of New Zealandean volcanologists has recently visited the volcano and sent the following more detailed reports:
***Ambae Volcano Update:10 Dec 2005***
"... Views and video obtained on December 9 by a TVNZ film crew show the cone is similar to that observed on December 8. The active vent is surrounded on 3 sides. The cone is not complete on its eastern side, but many small rocks could be seen breaking the lake surface, indicating it is very shallow there. Only 4 or 5 explosions were seen by the film crew, and these appeared weaker than those we saw on December 8 (however they only saw the activity for a very short time).
The eruptions are coming from a volcanic cone in the lake, ejecting water, mud and rocks, and a large (tall) plume of steam and gas. There continues to be two vents active, one producing the small explosions, and the second the steam and gas emissions. No volcanic ash is present in the steam plume. The eruptions are not having any immediate effect beyond Lake Vui. The level of the lake appears to remain stable, no large scale changes are apparent.
The level of eruptive activty remains at a similar level to that we have observed over the last week. The style of the eruption may change over the next 1-2 weeks if the cone continues to build, and the active vents become isolated from the lake. The eruptions will become dryer, and volcanic ash will probably be produced. We recommend that that the volcano should continue to be monitored and in 7-10 days time a detailed assessment is made of the activity. The Vanuatu Volcanic Alert Level should remain at Level 2."
GNS Sciences, NZ
In addition, the following, more detailed report was posted as well:
***Summary of Ambae Eruption - 10 December 2005***
"A small-scale volcanic eruption continues from active vents within the summit crater lake (Lake Vui) at Ambae. Molten material is entering the crater lake and reacting with the water to produce small explosive eruptions and a plume of steam and gas. The eruption has built a cone around the active vents, enclosing them on 3 sides, forming an island about 200m across and 50-60m high in the lake. There are two vents, one is erupting water, rocks and mud and the other is producing a tall column of steam and gas. To date the eruption has had little effect outside the crater lake (minor ashfall occurred only in the first three days of the eruption).
Five days of seismic recordings show a moderate level of seismic activity (mostly volcanic tremor), which is typical of an eruption of this size. There has been one measurement of the volcanic gas output measured, showing a moderate level of sulphur dioxide (SO2) gas (about 2000 t/d) from the active vents. This is typical of erupting volcanoes, but not of large eruptions. We have seen no change in the level of Lake Vui. There is also no evidence of ground uplift or cracking near the lake, which suggests there is no large volume of magma close to the surface.
As the volcanic activity is contining at a low level, we recommend that the Vanuatu Volcano Alert Level remains at Level 2.
The current activity appears to be similar in both style and size to that which occurred in 1966 and 1870 (when islands also formed in the lake). We think that the existing islands in the lake were formed by similar eruptions in the past.
Based on our observations and the history of Ambae we think there are four possible scenarios for future activty:
1. The eruption will continue with the same style and at a similar level for the next few days or weeks (most likely).
2. The cone currently forming in the lake continues to grow and starts to produce ash which falls on the island (as the cone grows this becomes as likely as number 1). This may also continue for a few days or weeks.
3. The level of actvity increases significantly producing larger ash falls and possibly lahars (less likely than number 2).
4. An eruption occurs to the northeast or southwest of the Lake Vui on the volcanic rifts and activity declines in the summit crater (less likely than numbers 1 and 2, but happened in 1870).
We recommend that that the volcano should continue to be monitored and in 7-10 days time a detailed assessment is made of the activity. Should the activity remain low it may become possible for people to return to their villages after the assessment."
Charlie Douglas, Morris Harrison (DGMWR)
Brad Scott, Steve Sherburn (GNS Sciences, NZ)
The tours this year on Santorini are now over, too, with lots of fun and great company as well. Thanks to all participants!
Before we send out our formal newsletter, when the programs for 2006 are completed, a quick notice to announce that Tom will offer a new, 12-days tour / expedition to the Rift Valley including Lengai volcano in Feb. and summer 2006, Costa Rica in late March and (probably) July 2006. As well, Tobias (who is right now touring in the Saronic Gulf) awaits with a new, exciting program on Milos, a wonderful, volcanic island in Greece! Other new or recently developped programs include Nisyros (Greece) and the Eifel region in Germany (details will come soon).
Greetings from Athens! Tom
Hello everybody on the tours in Indonesia this summer!
Back from a very pleasant tour in Italy, I have posted new dates for the Grand Tour of Italy's Volcanoes for 2006. Inscriptions open now![more]