Carol Stewart

Potential impacts from tephra fall to electric power systems: a review and mitigation strategies

Modern society is highly dependent on a reliable electricity supply. During explosive volcanic eruptions, tephra contamination of power networks (systems) can compromise the reliability of supply. Outages can have significant cascading impacts for other critical infrastructure sectors and for society as a whole. This paper summarises known impacts to power systems following tephra falls since 1980. The main impacts are (1) supply outages from insulator flashover caused by tephra contamination, (2) disruption of generation facilities, (3) controlled outages during tephra cleaning, (4) abrasion and corrosion of exposed equipment and (5) line (conductor) breakage due to tephra loading. Of these impacts, insulator flashover is the most common disruption. The review highlights multiple instances of electric power systems exhibiting tolerance to tephra falls, suggesting that failure thresholds exist and should be identified to avoid future unplanned interruptions. To address this need, we have produced a fragility function that quantifies the likelihood of insulator flashover at different thicknesses of tephra. Finally, based on our review of case studies, potential mitigation strategies are summarised. Specifically, avoiding tephra-induced insulator flashover by cleaning key facilities such as generation sites and transmission and distribution substations is of critical importance in maintaining the integrity of an electric power system.

The use of peat in the historical monitoring of trace metals in the atmosphere.

The concentrations of lead, zinc, copper, manganese, cadmium and calcium have been measured in three peat bogs. The distribution of Pb, Zn, Mn and Ca are dependent on the position and fluctuations of the water table. They all become depleted in the waterlogged, anaerobic zone. Copper and cadmium are uniformly distributed and appear to be immobilised, probably by the formation of metal/organic complexes, and independent of the acid and redox conditions existing in the bogs. The use of the concentration profiles of the metal ions as a means of historical monitoring of trace metal contamination is complex for Pb, Zn, Mn and Ca but may be more straightforward for Cu and Cd.

The transport of airborne trace elements copper, lead, cadmium, zinc and manganese from a city into rural areas.

The fluxes of the elements lead, zinc, copper, cadmium and manganese have been measured in the insoluble component of bulk deposition derived from Christchurch, New Zealand. Lead, zinc, copper and cadmium fluxes follow approximately exponential decay curves away from the city whereas manganese deposition showed little spatial variation. A similar composite source originating in the city is indicated for the lead zinc, copper and cadmium and a different major source occurs for manganese. In the city and nearby rural areas soil is not a major source of atmospheric lead, zinc, copper and cadmium, whereas at remote sites atmospheric levels of these elements are mostly soil derived. Seasonal variations in the bulk deposition are large within the city, and at upwind rural sites. The variations are controlled by meteorological conditions, in particular wind speed and the height of the mixing layer. Compared with overseas studies, the proportion of the metals occurring in the soluble fraction of the bulk deposition is low. This may be due to the relatively dry climate of the area.

Can Volcanic Ash Poison Water Supplies

Carol Stewart,*3 Lino Pizzolon,4 Thomas Wilson,1 Graham Leonard,I David Dewar,1 David Johnston,# and Shane Cronin33 7Private Consultant, Brooklyn, Wellington, New Zealand 8National University of Patagonia, Esquel, Argentina 6University of Canterbury, Christchurch, New Zealand IGNS Science, Avalon, Lower Hutt, New Zealand #GNS Science/Massey University, Avalon, Lower Hutt, New Zealand 77Massey University, Palmerston North, New Zealand * stewart.carol@xtra.co.nz

Historical monitoring of heavy metals in kahikatea ring wood in Christchurch, New Zealand

Abstract Tree ring wood was sampled from kahikatea trees in urban Christchurch, New Zealand, and from a background area on the west coast of South Island, New Zealand. The elements lead, cadmium, zinc, copper and manganese were analyzed in the wood using atomic absorption spectroscopy. Comparisons between the concentrations of the metals in the urban and background tree ring wood indicate a significant increase in lead, copper, zinc and cadmium since around 1860-70 for the urban trees. This can be accounted for by the start of urbanization and industrialization in Christchurch with the arrival of settlers from the United Kingdom. In the case of lead, a further increase occurred around 1950 corresponding to the escalating use of the motor car and leaded petrol. Manganese levels tended to fall from the late 19th century and may be associated with the draining of the swampy land in the city. It is suggested that the lead and cadmium in the trees mainly came from the incorporation of aerosol trapped by the bark, whereas the other three metals were probably mainly derived from the soil.

Impacts to agriculture and critical infrastructure in Argentina after ashfall from the 2011 eruption of the Cordón Caulle volcanic complex: an assessment of published damage and function thresholds

The 2011 Cordón Caulle (Chile) was a large silicic eruption that dispersed ashfall over 75,000 km2 of land in Central Argentina, affecting large parts of the Neuquén, Río Negro, and Chubut provinces, including the urban areas of Villa la Angostura, Bariloche and Jacobacci. These regions all received damage and disruption to critical infrastructure and agriculture due to the ashfall. We describe these impacts and classify them according to published damage/disruption states (DDS). DDS for infrastructure and agriculture were also assigned to each area using the tephra thickness thresholds suggested by previous studies reported in the volcanological literature. The objective of this study was to evaluate whether the impacts were as expected based on the DDS suggested thresholds, and to determine whether other factors, apart from ashfall thickness, played a part. DDS thresholds based on tephra thickness were a good predictor of the impacts that occurred in the semi-arid steppe area around Jacobacci. This was unexpected as the more severe impacts were related to the challenging environmental conditions (low precipitation levels, high levels of wind erosion) and the daily wind remobilisation of ash that occurred, rather than the ashfall thicknesses received. The temperate region, including Villa la Angostura and Bariloche, performed better than the DDS assigned by ashfall thickness suggested. Despite deposits as thick as 300 mm, full recovery occurred within months of the ashfall event. The DDS scales need to incorporate a wider range of system characteristics, and environmental and vulnerability factors, as we propose here.

Volcanic ashfall preparedness poster series: a collaborative process for reducing the vulnerability of critical infrastructure

Volcanic ashfall can be damaging and disruptive to critical infrastructure including electricity generation, transmission and distribution networks, drinking-water and wastewater treatment plants, roads, airports and communications networks. There is growing evidence that a range of preparedness and mitigation strategies can reduce ashfall impacts for critical infrastructure organisations. This paper describes a collaborative process used to create a suite of ten posters designed to improve the resilience of critical infrastructure organisations to volcanic ashfall hazards. Key features of this process were: 1) a partnership between critical infrastructure managers and other relevant government agencies with volcanic impact scientists, including extensive consultation and review phases; and 2) translation of volcanic impact research into practical management tools. Whilst these posters have been developed specifically for use in New Zealand, we propose that this development process has more widely applicable value for strengthening volcanic risk resilience in other settings.

Global Volcanic Hazards and Risk: Volcanic ash fall impacts

All explosive eruptions produce volcanic ash (fragments of volcanic rock < 2mm: Figure 12.1), which is then dispersed by prevailing winds and deposited as ash falls hundreds or even thousands of kilometres away. Volcanic ash suspended in the atmosphere is well known as a hazard for aviation, as was demonstrated during the 2010 eruption of Eyjafjallajökull, Iceland, which led to substantial disruption to flights in Europe and an estimated US

Impacts from volcanic ash fall

5 billion loss as global businesses and supply chains were affected (Ragona et al., 2011). Volcanic ash fall can also create considerable impacts on the ground. As a general rule, impacts will be more severe with increasing thickness of ash fall. Relatively thin falls (< 10 mm) may have adverse health effects for vulnerable individuals and can disrupt critical infrastructure services, aviation, agriculture and other socio-economic activities over potentially very large areas. Thick ash falls (>100 mm) may damage crops, vegetation and infrastructure, cause structural damage to buildings and create major clean-up requirements. However, they are typically confined to within tens of kilometres of the vent and, as they occur with large eruptions, are relatively rare.

Health Hazards Associated with Consumption of Roof-Collected Rainwater in Urban Areas in Emergency Situations

Abstract All explosive eruptions produce volcanic ash, fragments of volcanic rock generated when magma or vent material is explosively disintegrated during eruption. Volcanic ash is convected upwards within the eruption column and carried downwind, falling out of suspension and potentially affecting communities across hundreds of square kilometers. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation, and primary production (e.g. agriculture) can lead to significant societal impacts. Even relatively small eruptions such as the Eyjafjallajokull eruption in Iceland in 2010 (Volcanic Explosivity Index of 4) can cause widespread disruption, damage, and economic loss. Knowledge of the likely impacts can support mitigation actions, crisis planning, and emergency management activities. This chapter presents an overview of ash fall impacts for sectors of society including buildings, critical infrastructure, and agriculture; and discuss associated socioeconomic factors. We also discuss the likely response (vulnerability) of these key sectors to ash fall impacts. Broad relationships between volcanic ash thickness and levels of damage and disruption have been outlined. Understanding these vulnerabilities is an essential step towards building resilience for communities.