All explosive eruptions generate tephra, fragments of volcanic rock that are produced when magma or vent material is explosively disintegrated during eruption. Tephra is then convected upwards with the eruption column and carried downwind, falling out of suspension and potentially affecting communities across hundreds, or even thousands, of square kilometres. Although tephra falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to potentially substantial societal impacts. Even relatively small eruptions, such as the 2010 Eyjafjallajökull eruption in Iceland (VEI 4 on a logarithmic scale of 0 to 8 ), can cause widespread disruption, damage and economic loss. Given the potentially large geographic dispersal of tephra, and the substantial impacts that even small (a few mm) deposits can have for society, this background paper elaborates upon the tephra component of the volcanic contribution to the UN Global Assessment Report 2015. Here, we provide an overview of tephra fall hazard at global, regional and local scales and discuss the key components required to carry these hazard estimates forward to risk: namely identification of likely impacts and the response (vulnerability) of key sectors of society to tephra fall impact. Broad relationships between tephra thickness and key levels of damage have been outlined. Greater knowledge of future tephra fall hazard and associated impacts can support mitigation actions, crisis planning and emergency management activities and is an essential step towards building resilience for communities.

Volcanic ash represents a serious hazard to communities living in the vicinity of active volcanoes in developing countries like Indonesia. Geoscience Australia, the Australia-Indonesia Facility for Disaster Reduction (AIFDR) and the Indonesian Centre for Volcanology and Geohazard Mitigation (CVGHM) have adapted an existing open source volcanic ash dispersion model for use in Indonesia. The core model is the widely used volcanic ash dispersion model FALL3D. A python wrapper has been developed, which simplifies the use of FALL3D for those with little or no background in computational modelling. An application example is described here for Gunung Ciremai in West Java, Indonesia. Scenarios were run using eruptive parameters within the acceptable range of possible future events for this volcano, granulometry as determined through field studies and a meteorological dataset that represented a complete range of possible wind conditions expected during the dry and rainy seasons for the region. Implications for varying degrees of hazard associated with volcanic ash ground loading on nearby communities for dry versus rainy season wind conditions is discussed. Communities located on the western side of Gunung Ciremai are highly susceptible to volcanic ash ground loading regardless of the season whereas communities on the eastern side are found to be more susceptible during the rainy season months than during the dry. This is attributed to prevailing wind conditions during the rainy season that include a strong easterly component. These hazard maps can be used for hazard and impact analysis and can help focus mitigation efforts on communities most at risk.

Volcanic ash represents a serious hazard to communities living in the vicinity of active volcanoes in developing countries like Indonesia. Geoscience Australia, the Australia-Indonesia Facility for Disaster Reduction (AIFDR) and the Indonesian Centre for Volcanology and Geohazard Mitigation (CVGHM) have adapted an existing open source volcanic ash dispersion model for use in Indonesia. The core model is the widely used volcanic ash dispersion model FALL3D. A python wrapper has been developed, which simplifies the use of FALL3D for those with little or no background in computational modelling. An application example is described here for Gunung Ciremai in West Java, Indonesia. Scenarios were run using eruptive parameters within the acceptable range of possible future events for this volcano, granulometry as determined through field studies and a meteorological dataset that represented a complete range of possible wind conditions expected during the dry and rainy seasons for the region. Implications for varying degrees of hazard associated with volcanic ash ground loading on nearby communities for dry versus rainy season wind conditions is discussed. Communities located on the western side of Gunung Ciremai are highly susceptible to volcanic ash ground loading regardless of the season whereas communities on the eastern side are found to be more susceptible during the rainy season months than during the dry. This is attributed to prevailing wind conditions during the rainy season that include a strong easterly component. These hazard maps can be used for hazard and impact analysis and can help focus mitigation efforts on communities most at risk.

Understanding the potential magnitude, severity and impact of future volcanic eruptions on communities living in close proximity to volcanic sources is essential for any attempt to reduce natural disaster risk in Papua New Guinea. Geoscience Australia is working in partnership with the Rabaul Volcanological Observatory (RVO) to build the capacity of volcanologists to undertake volcanic ash dispersal modelling, to interpret the outputs and to incorporate the data where appropriate into a new series of volcanic hazard maps for a pilot province (East New Britain; ENB). A modified procedure for volcanic ash dispersal modelling (PF3D) was developed in 2009 by Geoscience Australia and its regional partners in Indonesia and the Philippines which modify the modelling procedure of FALL3D, a widely used and well validated volcanic ash dispersal model, in line with the needs of government agencies and emergency managers in the Asia-Pacific region. PF3D introduces a number of enhancements to the procedure for FALL3D that do not change the operation or functionality of the core model but increase its accessibility for volcanologists working in developing countries like Papua New Guinea. The three year program, funded by the Australian Agency for International Development (AusAID) provided training in the use and application of PF3D for RVO staff through the development of new volcanic hazard and risk information for ENB. A significant achievement for the program has been the continuous involvement of community groups who, through a series of workshops held in ENB, have been heavily involved in discussions around the kind of volcano science being undertaken, providing feedback on outputs and in driving the design and production of education and public awareness materials (books, posters etc) which will be used for communicating the outputs of the program in local schools and other community centres as part of a larger planning and preparedness campaign.

Papua New Guinea and Australia have a long-standing and ongoing association in understanding volcanic risk. The Rabaul Volcanological Observatory (RVO) in Papua New Guinea (PNG) was established by the Australian Government, following the devastating 1937 Rabaul eruption, which killed over 500 people and caused widespread damage. The Australian Bureau of Mineral Resources (BMR) re-established the RVO in 1950 following World War II and managed its operations until PNG independence in 1975. Geoscience Australia (GA) has since continued to hold strong links with RVO. When the major eruption of Rabaul volcano commenced in September 1994, the Australian Aid programme approached GA to provide emergency assistance to the RVO during this period. This led to the development of the Papua New Guinea-Australia initiative the Volcanological Service Support Project (VSSP) in 1995/96. Here we present a brief overview of the activities carried out in collaboration between the Papua New Guinea and Australian Governments over the past twenty years, drawing on examples from the VSSP to demonstrate a multi-layered approach to Disaster Risk Reduction (DRR). With components spanning monitoring, modeling, information management and community awareness, and participants ranging from individual community members to national agencies, each element has contributed to our understanding of volcanic hazard and risk in PNG and the Asia-Pacific. We highlight some of the milestones of the past twenty years and examine how the long history of past activities has shaped the design of the current cross-organisational DRR partnership.

Have you ever wondered what lava looks like when it cools down? This short video introduces rocks from volcanoes and their features using some of the samples in the Geoscience Australia Education Centre. Viewers are shown different types of lava rock, bombs, obsidian and pumice. The video is suitable for middle primary and older students as well as a general audience; it introduces some technical terms and uses samples available for school students to handle during visits to the Centre.

This technical report details the methods and results the drilling programs of the Upper Burdekin Groundwater Project conducted as part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. This report was written by Queensland Government collaborators in the Department of Environment and Science, and is published here as supplied to Geoscience Australia at the conclusion of the project. The drilling program itself was conducted by the Department of Environment and Science as part of the Upper Burdekin Groundwater Project. A total of 17 holes were drilled in 2017-18 at 13 sites with a total combined depth of 943.2 metres. These comprise selected locations across both the Nulla Basalt Province and McBride Basalt Province. A network of 15 monitoring bores were constructed with two test holes backfilled and decommissioned.

Significant advances have been made in recent years in probabilistic analysis of geological hazards. Analyses of this kind are concerned with producing estimates of the probability of occurrence of a hazard metric at a site given the location, magnitude, and frequency of hazardous events around that site. Significant advancements have been made towards the probabilistic assessment of earthquake hazard leading to the development of Probabilistic Seismic Hazard Analysis (PSHA). PSHA is a method for assessing and expressing the probability of earthquake hazard at a site of interest in terms of probability of exceeding certain ground motion intensities. Probabilistic methods for assessing volcanic ash hazard at a regional-scale are less advanced. The methodology presented here, Probabilistic Volcanic Ash Hazard Analysis (PVAHA), modifies the four-step procedure of PSHA for volcanic ash and applies it at a regional-scale. PVAHA considers a magnitude-frequency distribution of eruptions and associated volcanic ash load attenuation relationships and integrates across all possible events to arrive at an annual exceedance probability for each site across a region of interest. PVAHA can be aggregated to generate maps that visually convey the expected volcanic ash hazard for sites across the region at return periods of interest, or disaggregated to determine the causal factors which dominate volcanic ash hazard at individual sites. PVAHA results can be used to identify priority areas for more detailed, local scale ash dispersal modeling that can be used to inform disaster risk reduction efforts.

We present a new geological map of Warrumbungle Volcano created from volcanic facies field mapping, new geophysical, geochemical, and geochronological data as well as data from previous studies. Field mapping and petrography defined 19 volcanic and 2 mixed volcanic-sedimentary facies. Facies identification and distribution in conjunction with geochemical analyses indicate an early shield-forming phase of predominantly mafic and intermediate lavas and pyroclastic deposits, and minor felsic lavas deposited on an irregularly eroded basement of Surat and Gunnedah basin rocks. The shield was subsequently intruded by felsic intermediate to felsic magmas that formed dykes and other intrusions including possible cryptodomes, and also erupted as lava domes and block-and-ash-flow deposits. A radial dyke swarm cross-cuts most units, although is concentrated within basement sandstone surrounding the central area of the volcano, suggesting late inflation accompanied by dyke emplacement. Geochemistry indicates differentiation of a single although repeatedly recharged alkaline magmatic suite. Fractionation of olivine, Ti-magnetite and clinopyroxene occurred in mafic magmas, and after reaching 62 wt% SiO2 crystallisation of apatite and alkali feldspar took place. A new U-Pb zircon SHRIMP magmatic crystallisation age of 16.25 +/- 0.12 Ma on a felsic block-and-ash flow deposit is in agreement with the recalculated 40Ar/39Ar isochron dates of previous workers. Based on our mapping and the use of volcanic facies to define mappable units, we recommend the previous Warrumbungle Volcanics be elevated from formation to group status and renamed the Warrumbungle Volcanic Complex.