Volcanic gases – impacts on air quality
Images of Whakaari/White Island, Ngāuruhoe and Ruapehu eruptions have one thing in common – enormous plumes of steam, gases and ash. Water vapour is usually the most abundant gas expelled, followed by carbon dioxide, sulfur dioxide and hydrogen sulfide.
Whakaari/White Island
The summit of a submerged stratovolcano (a type of cone volcano). Measuring from the seafloor, the volcano is over 1,900 m in height and is still active, releasing gases and steam regularly. The most recent eruption was in December 2019.
Acknowledgement: GeoNet
The types and amounts of gases released during an eruption are mostly determined by the magma’s composition, the temperature and pressure of the system, the tectonic setting (hot spot versus subduction zone) and whether the magma interacts with water.
One way to visualise gas formation is with a bottle of fizzy drink – a carbonated liquid. When the bottle is opened, the pressure decreases and carbon dioxide bubbles form and rise to the top of the bottle. A similar process happens with magma – as it rises, the pressure decreases and gases dissolved in the magma expand rapidly.
Volcanic gases associated with the Auckland Volcanic Field
Magma that underlies the Auckland Volcanic Field is basaltic. Basalt magma is formed at high temperatures (around 1,200°C). When it comes out of the volcano, it is a hot and runny liquid. The main volcanic gas released is water, which is visible as a steam plume. Other gases from the basaltic magma include sulfur dioxide (SO₂) and carbon dioxide (CO₂) with lesser amounts of hydrogen sulfide (H₂S), carbon monoxide (CO), hydrogen chloride (HCl) and hydrogen fluoride (HF).
We often hear about the dangers of volcanic ash when an eruption occurs, but gases also pose significant risks. Gas concentrations will depend on the amounts released during the eruption, distance from the source, wind speed and wind direction.
Air quality in the Auckland Volcanic Field will be affected by a volcanic event – with implications for humans and the environment. The main health hazard is from sulfur dioxide. When it comes in contact with moist surfaces like your eyes, nose and throat, it forms sulfuric acid. Other gases also pose risks to air quality.
Assessing volcanic hazards and risks in Auckland
Researchers from the DEVORA (DEtermining VOlcanic Risk in Auckland) programme study all aspects of volcanoes, including the chemical composition of their magma and the volcanic gases they produce. As part of their outreach, the DEVORA team uses infographics to raise awareness about the potential impacts of an eruption.
Volcanic gas, acid rain and ash from possible future Auckland Volcanic Field eruptions
An eruption arising from the Auckland Volcanic Field will have impacts on air quality depending on the amount of gas released, distance from the source, wind speed and wind direction.
Download the infographic as a PDF.
Using infographics as teaching tools
Science knowledge is often communicated through visual representations – graphs, diagrams and infographics. Each type of visual representation has literacy components that ākonga may need support to understand. The science capability ‘Interpret representations’ encourages ākonga to think about how data is presented, what the representation tells us and how it gets the message across.
Interrogate the infographic with questions – for example:
Who created the infographic?
Who is the intended audience?
What is the central theme?
Are there subthemes?
What makes the message credible?
What other information might you need to understand the infographic?
Are there specific scientific words or terms?
Where can you find the information that might fill in these gaps?
By their nature, infographics use concise text, so we’ve placed each DEVORA infographic within an article that includes background information and links to related content. Use them to explore and deepen understanding of concepts within the infographics.
DEVORA’s suite of infographics:
City of volcanoes – the Auckland Volcanic Field Ngā Tapuwae ō Mataaho supported by the article Tāmaki Makaurau – city of volcanoes.
Hidden eruptions – the search for Auckland’s volcanic past supported by the article The search for Auckland’s volcanic past.
Rangitoto: odd one out – the story of Auckland’s largest volcano supported by the article Rangitoto – Auckland’s largest volcano.
Eruption impacts – how would an eruption in Tāmaki Makaurau impact the city? supported by the article Auckland Volcanic Field – eruption impacts.
The floor is lava – lava flows from Auckland’s volcanoes supported by the article Lava flows from Auckland’s volcanoes.
Ngā maunga – a brief history of maunga (mountains) in the Auckland Volcanic Field supported by the article Ngā maunga – Tāmaki Makaurau Auckland’s volcanic field.
Volcanic gas, acid rain and ash from possible future Auckland Volcanic Field eruptions supported by the article Volcanic gases – impacts on air quality.
Nature of science in the curriculum
Developing visual and numerical literacies such as those used in infographics supports students to analyse and interpret data. The infographics also enable students to engage with science in social and cultural contexts.
Related content and activity ideas
The article Volcanoes resources – planning pathways provides additional pedagogical information. It also includes the interactive Planning pathways using volcano resources, in which we curate resources into key science concepts and topics. This curation has a specific focus on Auckland’s volcanoes.
Read more about carbon dioxide and sulfur.
The DEVORA programme aims to educate the public so that we know how to act during a possible volcanic event. Use these activities to show how scientists and others help us stay safe during emergencies:
Who’s on your team? – ākonga work in small groups to select a 6-member disaster response team from a set of 12 biography cards.
Home disaster kit – ākonga select items to include in a home disaster kit in case of emergency.
5-Minute Volcano – an active, collaborative board game about natural disaster preparedness.
Magma Pop is a virtual game that helps ākonga learn about Earth’s most common minerals and the processes that happen in a magma chamber.
Useful links
Visit the DEVORA website to learn more about its work – including teaching resources and opportunities for free outreach.
GeoNet (a collaboration between Natural Hazards Commission Toka Tū Ake and Earth Sciences New Zealand) uses techniques such as gas monitoring to observe New Zealand volcanoes. Its website also has up-to-date information about earthquakes, tsunamis and landslides.
Acknowledgement
This resource has been produced with the support of DEVORA (DEtermining VOlcanic Risk in Auckland).
DEtermining VOlcanic Risk in Auckland (DEVORA)
DEtermining VOlcanic Risk in Auckland (DEVORA) is a multi-agency, transdisciplinary, collaborative research programme led by volcanologists at the University of Auckland and Earth Sciences New Zealand (formerly GNS Science) and funded by the Natural Hazards Commission Toka Tū Ake (NHC) and Auckland Council.