Volcanic Alert Bulletin WI-2013/1 - White Island Volcano
7 January 2013, 2:00 pm - Lava dome eruption episode now over; Volcanic Alert changed to level 1; Aviation Colour Code
changed to Yellow.
GNS Science Volcanologists today lowered the Volcanic Alert Level for White Island to level 1 and the Aviation Colour
Code to Yellow. This reflects the end of the current period of eruption which involved the growth of a small lava dome
in the crater.
The lava dome that was first observed in late November by tour operators has been monitored over the last 6 weeks. The
most recent visit was on 1st January 2013 and this showed that the dome had not grown since previous visits on the 10th
and 20th December 2012. As such we consider that the current episode of eruption to have ceased.
Lava dome temperatures measured on the 1st January were at around 200-240°C and the nearby hot lake was 70-80°C. These
temperatures are similar to those made previously. GNS Science Volcanologist Nico Fournier said that “the dome looked
exactly the same as it did on our previous visits. Good viewing conditions allowed us to get some remote temperature
measurements using an infrared thermometer. The hot lake was really fizzing, lots of gas coming through it”
Results of airborne gas measurements from 20th December showed that White Island is emitting volcanic gases at the rate
of approximately 400T/d SO2, 1300T/d CO2 and 10T/d H2S.
Seismicity continues to show elevated levels of tremor.
Observers of the GeoNet webcams may notice a slight glow in the night time images which is related to the relatively hot
dome and gases.
Even though the current episode of eruptive activity is over White Island still remains in a heightened state of unrest
and future eruptions are still possible with little or no warning.
GNS Science continues to closely monitor White Island through the GeoNet project.
Background
The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates departure from typical surface
background activity.
Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. A
reduction to Code Yellow from Orange indicates volcanic activity has decreased significantly but continues to be closely
monitored for possible renewed increase.
Volcanoes can erupt in many different ways. They can erupt explosively like Tongariro in 2012 when rocks and ash were
hurled into the sky. They can erupt effusively with lava flows like Ngauruhoe in 1954 or in Hawaii. A lava dome is a
type of effusive eruption.
The GeoNet project is funded by EQC and provides monitoring for all of New Zealand’s volcanoes.
Craig Miller
Duty Volcanologist
ENDS