Vanuatu

Vanuatu Volcano Alert Bulletin n°7 - Ambae Activity (21 July 2018)

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AMBAE VOLCANO
15°24’0”S 167°50’0”E Summit 4908ft (1496m)
Current Vanuatu Volcano Alert Level: Level 3

Ambae volcano is in the minor eruption state. The Volcanic Alert Level is raised to Level 3 .

The volcanic eruption at Ambae confined inside the Lake Voui is consistent with the Volcanic Alert Level 3. Scientific analyses confirm that the current activity is similar to the volcanic activity of March 2018 with more and sustained emissions of volcanic ashes. The possibility of imminent increasing activity is low. The Danger Zone for life safety is now limited at 3 km radius from the active vent and areas located in the Yellow Zone (See Map below).

Observations flights on 13th and 20th July 2018 confirm the activity at the volcano is only occurring in one of the summit crater lakes (Lake Voui) and is not changing. Photographs taken during observation flights show the activity consists of explosions and ejection of hot rocks from the eruptive vents accompanied by ash emission. A small –scale eruption continues in Lake Voui.

The presence of ash that has fallen on Ambae during the last eruptive phases and now will continue to change the behaviour of streams and creeks when it rains. The creeks and streams can produce floods and carry a lot more debris (sands, gravel and boulders). The flow path of streams and creeks could change due to the flood debris. Landslide may occur at some areas during heavy rain fall.

These observations and the analysis of seismic data confirm that the volcano activity is in the minor eruption state. The volcano activity consist of ongoing emission of steam and/or gases and ashes. The local population from Ambae and from neighbouring island can hear rumbling, volcanic explosions from volcano, smelt volcanic gases, see volcanic ash and gas plume and glows over the mountain at night.

Significant impact of ashes and gases emission to villages at Ambae started in March 2018, when the Volcanic Alert level was raised to Level 3. With the drop of the volcanic activity in May, the Alert Level was lowered to Level 2 in June. Observations of the current activity are consistent with the Alert Level 3 activity. Level 3 indicates ‘Minor eruption; Danger is now at 3 km around the volcanic vents and areas inside the Yellow Zone’ . The possibility that the Ambae volcano activity escalate to the level of moderate eruption is moderate to low .

Ambae volcano is a very large volcano and is frequently active. A large-scale eruption about 400 years ago built a volcanic cone in the summit crater and the crater is now filled by Lake Voui; the modern active vent area underlies Lake Voui. Historic activity is poorly known, but there is documented activity in 1530, 1670, 1870, 1915 and 1966. All documented activity has been from the summit crater (Lake Voui) except for the 1670 activity, which included a flank eruption producing lava flows at Ndui Ndui. The current eruption episode started in 1991, with eruptions in 1995, 2005, 2016 and 2017. The current eruption is focused in the summit crater and there are no indications of activity elsewhere on Ambae Island for now.

Advise to all tourism agencies, local authorities, people of Ambae and the general public not to access the Danger Zone which is now about 3 km radius from the eruptive vent. In this area flying rocks, volcanic gases and ashes are expected. Villages in the Yellow Colour may continue to expect change in streams and creeks flows during rain fall (See map below). Villages from Ambae island will continue to experience impacts of volcanic gases and ashes especially those exposed to prevailing trade winds direction. For more information about reducing risks of the above (ashes and gases), Please see Volcano Key Messages at the link below: http://www.vmgd.gov.vu/vmgd/index.php/geohazards/volcano/volcano-info/re... .

The Vanuatu Meteorology and Geohazards Department will continue to closely monitor this volcano activity. More information will be provided as available.