Volcanic Alert Bulletin WI-2013/21 - White Island Volcano
Volcanic unrest continues at White Island (Whakāri). Volcanic tremor levels have remained slightly elevated since the eruption on 20 August. A further small energetic steam venting event occurred on 4 October around 4.30 pm. This generated a steam plume above the island that was seen from the mainland. The Volcanic Alert Level remains at 1 and the Aviation Colour Code at Green.
Volcanic tremor levels have been elevated since about 24 September, but are at lower levels than those during eruptive activity during the January to April period this year.
GNS Science volcanologists visited the island on 4 October to make gas measurements, repair equipment damaged by the recent storms and record observations.
The 20 August 2013 eruption has created a new basin that is now filled with water. The lava dome area appears unchanged except for some small ponds in the area.
Recent activity has moved the focus of activity within the active crater area. The newly established lake is further to the north-east by a few tens of metres. There has also been several landslides from the Main Crater walls. The landslides are most likely related to the recent weather events.
Video compilation from the web camera on the North Rim shows activity at 03:36h 57s (UTC) pulsing above the crater rim, while the camera at Whakatane shows the general increase of emissions from around 03:35h (UTC) on 4 October. Note times in the video clips are in UTC (Co-ordinated Universal Time, 13 hours behind local time). The video clips can be seen at White Island North Rim: http://youtu.be/NGviBdjanXY and White Island Whakatane http://youtu.be/iMeMA6shgt0.
Gas flux from the volcano also remains slightly elevated and is consistent with the small scale unrest occurring on the island. Daily sulphur dioxide (SO2) gas flux for the last month has ranged from 117 to 662 tons per day. These are typical of the last 12-18 months but are higher than those measured before the unrest started in July 2012.
View of active vent area from the summit on 1 May 2013
View of active vent area from the summit on 4 October 2013. View of active vent area from the summit on 4 October 2013. Note how the active vent area in the centre has moved to the left and the pinky-red landslide debris in the foreground.
While the eruptive activity at White Island is currently at a low level, eruptions similar to those experienced over the last 15 months are possible with no prior warning. The larger eruptions can eject mud and rocks and may impact the crater floor area to which visitors have access.
Nico Fournier Duty Volcanologist
Contact: Brad Scott