Published: Fri Jul 16 2021 9:30 AM
Residents in the Bay of Plenty, and visitors to our volcano cameras page may have spotted some large plumes from Whakaari/White Island recently, as well as a strange glow on the night cameras. We take a look into the cause of these volcanic sights.
The cause of the large volcanic plume
With ideal weather conditions during the last couple of weeks, the residents of Bay of Plenty were able to view large steam and gas plumes from Whakaari/White Island. These were also visible via the web camera watching the volcano from Whakatane. The steam and gas plume originates from several active vents on the island and are clustered in and around the craters formed in December 2019.
Several factors contribute to how the steam and gas plumes appear above the volcano. These include heat flow, gas output, and the presence of ground water, lakelets or crater lakes. Humidity, dew point, air temperature and windspeed can also play a role. Line all of these up like we did over the last couple of weeks and you can have large spectacular steam and gas plumes over the volcano.
Gas is formed from subduction and magmatic processes at depth and is discharged at volcanoes and geothermal areas. The gas leaks from the rising geothermal fluids and molten rock (magma). Steam-water vapour (H2O) is the most common volcanic gas constituent. However, there are several other gas species present. After steam, in order of abundance they are carbon dioxide (CO2) sulphur dioxide (SO2) and hydrogen sulphide (H2S). GeoNet measures the amount of these present during regular gas flights.
What is the Night Glow?
Since 30 June we have seen a night glow return to the island, visible from our Crater Rim camera at night. Our Volcanic cameras have both daylight and low light cameras installed, allowing pictures to be taken at night when there is enough ambient light (such as from a full moon). The low light cameras are also able to see the hot steam and gas vents, and these appear as a ‘glow’ on our cameras on the island. This usually requires moderate-strong and hot emissions from the vents on the volcano for this to occur. Observations from a flight on 15 July confirmed temperatures of 500-600 °C are now present.
You can clearly see the night glow in the image below, with the daytime view for comparison. This 'glow' is only visible in the near infra-red with our webcam and unlikely to be visible with the naked eye.
Why have cameras?
The cameras allow us to keep an eye on the volcano. They are setup to take an image every second and then transmit an image every 10 minutes to our data centres and website. If we wish to see images during unrest or an eruption, we can download the high data rate images as needed. They are a great aid to our monitoring.
Attributable to - Brad Scott – GNS Science Volcano Specialist
Media enquiries - firstname.lastname@example.org or 021 574 541