May 12, 2021

Maori News & Indigenous Views

Volcanic Alert Bulletin – White Island Volcano

2 min read

No further eruptive activity has occurred at White Island (Whakaari) since the moderate eruption on the evening of 11 October. Volcano seismic activity has declined but remains variable. Gas flux remains high. Volcanic unrest continues at White Island. TheVolcanic Alert Levelhas been lowered from Level 2 to Level 1.Aviation Colour Coderemains at Yellow.

Since the moderate eruption on the evening of 11 October no further eruptions have been detected at White Island. A visit to examine and sample the effects of the eruption and repair damaged equipment has confirmed the entire Main Crater floor was affected. Ejecta extended to over 350 m from the active vent and a wet volcanic surge cloud enveloped the Main Crater, depositing a muddy layer.

White-Island-28766-20-lgeVolcanic tremor levels decreased after the eruption on 11 October and have remained at variable levels since then. A successful gas flight was made on 17 October. The SO2flux was 450 tonnes per day, CO21140 tonnes per day and H2S 12 tonnes per day. The SO2and H2S flux is little changed,CO2has decreased from the previous measurements on 23 August. The gas data suggests that there is continuing degasing of a shallow body of magma (molten material). The dailySO2measurements from data logging equipment on the island show theSO2flux has ranged from 408 to 1400 tonnes per day over the last week and the average flux remains elevated.

White Island remains in a state of volcanic unrest with instability in the volcano-hydrothermal system. A range of eruptive activity can occur under these conditions with little or no prior warning. The larger eruptions can eject mud and rocks and may impact the crater floor area.

GNS Science is continuing to closely monitor the activity at White Island (and other New Zealand volcanoes) through the GeoNet project, and will provide more information as it becomes available.

Brad Scott
Duty Volcanologist

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