A short-lived period of minor ash emission occurred at White Island volcano, New Zealand at about 19:40 UTC on August 21, 2021, GeoNet's Duty Volcanologist Steven Sherburn reported in a bulletin released August 24. The Volcanic Alert Level remains at 2 and the Aviation Color Code at Yellow.
A notable volcanic earthquake was recorded at White Island volcano at 19:40 UTC on August 18 (07:40 LT, August 19).
"The earthquake continued for about 10 minutes, but it was not accompanied by any eruptive activity that could be observed, either by webcam images, or by air pressure sensors," Sherburn said1, adding that no relationship has been established between the volcanic earthquake and the period of minor ash emission observed at the active vent area at about 19:40 UTC on August 21 (07:40 LT, August 22).
Based on webcam observations, the ash emission on August 21 persisted for about two minutes. It's unlikely to have produced a plume large enough to create any ashfall, even on the island.
Webcam images continue to show night glow, suggesting that temperatures in the active vent area probably remain around 500 – 600 °C (932 – 1 112 °F), like recent observations.
Satellite radar data continue to show small amounts of ground deformation around the active vent and lake area.
"These observations do not change recent interpretations that a fresh magma intrusion to shallow levels has occurred since June 2021," Sherburn said.
"The ash emission observed on Sunday may be related to shallow magma beneath the active vents, but its short duration suggests that unstable material falling into the active vent, subsequently to be fragmented and then ejected by gas pressure, may be a more likely explanation. This type of activity has occurred many times in the past, including since the December 2019 eruption.
"Equipment that provides real-time monitoring on the island is currently degraded and we are continuing to work on restoration options."
The current level of activity is consistent with moderate levels of unrest.
1 Minor, short-lived ash emission from Whakaari/White Island. Volcanic Alert Level remains at 2 – VOLCANIC ALERT BULLETIN WI – 2021/09 – GeoNet
Featured image: White Island volcano, New Zealand on August 18, 2021. Credit: Copernicus EU/Sentinel-2, TW
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