LAKE VOUI
“The Lake of Spirits”

VOLCANIC FORM:  Basaltic shield volcano
 
 

FORMATION:  Lake Voui was formed approximately 425 years ago after an explosive eruption that excavated two craters at the summit of Lombenben Volcano. Lake Voui fills a broad pyroclastic cone that accumulated in one of the two explosion craters.  The second explosion crater, located west of Lake Voui, contains a swampy area known as Manaro Ngoro, which periodically fills with water to form an ephemeral lake.
 

Three lakes adorn the summit of Lombenben Volcano.  Manaro Ngoro (foreground), Lake Voui (middle), and Lake Manaro Lakua (background).  Lake Voui fills the active crater of Lombenben Volcano, while Manaro Ngoro fills a dormant crater.  Lake Manaro Lakua does not fill an explosion crater, but has accumulated in a low-lying area of the caldera.
 
 
 
 
 
 
 
 
 
 
 
 

RECENT ACTIVITY:

• 20th Century - Fumarolic emissions and emissions of gas bubbles from Lake Voui.  Historical accounts tell of “rock and water falls” and earth tremors occurring between 1910 and 1920.
• 1991-1994 – Large diameter gas bubbles produced in Lake Voui.  Deforestation along the edges of the crater and erosion of the islets within Lake Voui caused by emission of sulphurous gases.
•  March 3, 1995 – Phreatic explosion originating from Lake Voui results in a column of steam rising 2000 – 3000m      high.
• March 4 – 6, 1995 - High “tremor” signal (20 microns) recorded at seismographic station.  Lake level is reported to be ~4.8m above the normal level.
• March – June 1995 – The increase in volcanic activity leads an official alert being issued to the island of Ambae on March 15, 1995.  Constant degassing from Lake Voui.  Convection cells 300 – 400 m in diameter are apparent in the lake.  Lake level drops ~2m by April 6th and ~5m by June 27th.

                                     Lake Voui during quiescent period
 

Photo taken December 1, 1995 of the now devegetated islets in Lake Voui (Photo: M. Lardy, in: Lardy et al, 1996).
Due to increased volcanic activity and the emission of sulphurous gases, this group of islets has experienced both the loss of vegetation and severe erosion.
 
 

REFERENCES

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1. Title: Proposal for the installation of monitoring equipment on the volcano Lombenben (Ambae Island, Republic of Vanuatu).
Authors: Lardy, Michel; Halbwachs, Michel.
Book Title: Sciences de la Terre
Volume: no. 19
Year: 1996
Publisher: ORSTOM

2. Title: Aoba (Ambae) Mission Report 26 & 27 June, 1995 (Vanuatu).
Authors: Lardy, Michel; Wiart, Pierre; Charley, Douglas.
Book Title: Sciences de la Terre
Volume: 11
Year: 1995
Publisher: ORSTOM

3. Title: Aoba (Vanuatu): crater lake exhibits convection cells and steaming as level drops.
Authors: Lardy, M; Charley, D; Wiart, P; Kalkaua, K; Regnier, M; Temakon, S; Tahi, N; Robin, C; Monzier, M; Eissen, J.P; Metaxian, J.P.
Book Title: Bulletin of the Global Volcanism Network
Volume: 20, no. 8
Year: August, 1995
Source: pp. 25 - 28

4. Title: Les lacs de cratere du volcan d'AOBA
Authors: Gardissat, P.
Book Title: NABANGA
Volume: 52
Year: 1977

5.  Title: Evolution of Aoba caldera volcano, New Hebrides
Authors: Warden, A.J.
Book Title: Bulletin Volcanologique
Volume: 34, no. 1
Year: 1970
Source: pp. 107 - 140.
 

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