This thesis is a palaeoenviromnental investigation into possible non-climatic effects on the environment from volcanic ash fall and toxic emissions outside the blast zone of a volcanic eruption. These effects are determined from palynological and geochemical changes following tephra fall at a range of sites across the North Island of New Zealand which were located at increasing distances from the main volcanic source, the Taupo Volcanic Zone. These sites collectively covered a wide variety of habitats existing under different climatic regimes. The first site is a peat bog at a warm temperate, comparatively unstable coastal location, Matakana Island. The peat profile extends to 1000 yrs BP and contains the Kaharoa Tephra layer, erupted around the time of early human settlement in New Zealand. The second study site is Kaipo peat bog which, in contrast to Matakana Island, is an upland sub-alpine site existing under a harsher climatic regime with cool temperatures, strong winds and heavy rainfall. The Kaipo record covers the Holocene period up to recent times. Lake Rotoroa is the third site which is located inland, sheltered within the Waikato valley, an area of rich fertile soils and mild temperate climate. The Lake Rotoroa record extends to approximately 15,000 yrs BP including the end of the last glacial period and the Holocene. The final site investigated, Kohuora bog, is situated in an extinct late Quaternary volcanic crater within Auckland urban area, a region of warm temperate climate. This record extends from the last glacial period to the present. Fine resolution sampling methods were employed above tephra layers preserved at each of these sites to examine the immediate short-term palaeoenvironmental impacts from volcanic tephra deposition. The methods used included pollen analysis, and the relatively new technique of Energy Dispersive X-ray Micro Analysis (EDMA) which investigated changes in sediment geochemistry to provide further information on local environmental change following tephra impact. The use of pollen analysis together with EDMA proved beneficial in assessing overall short term environmental impacts from tephra fell. Results revealed that thicker tephra layers did not always cause extensive environmental damage, as impacts seen above the 0.5 cm thick Egmont 15 Tephra at Lake Rotoroa were among the most significant recorded at this site. Instead, the contributing factors of prevailing climate and local site factors (e.g. drainage, soils, vegetation cover and shelter) at the time of an eruption, together with local forest diversity and species sensitivity to tephra deposition, proved more important in determining the degree of tephra impact. Taxa found to be particularly sensitive to tephra deposition included Halocarpus, with inconsistent impacts from tephra fell on Dacrydium and Metrosideros. Duration of tephra impacts varied between sites, but broad estimates from the results showed the time taken for recovery of forest vegetation following an eruption was >100 years, with environmental stability returning after a minimum period of 50 years. The results from Matakana Island revealed that any possible tephra impacts from deposition of the Kaharoa Tephra were obscured owing to large-scale deforestation following Polynesian settlement on the island around the time of the Kaharoa eruption. This study indicates the importance of investigating distal volcanic impacts prior to human settlement to eliminate ambiguity in interpretation of palaeoenvironmental data.

The number of people suffering from natural disasters, and the economic impact of those disasters, continue to increase as the years go by. Better preparation and risk management strategies can help lessen the impacts of these disasters. One important aspect of risk management is risk assessment, which can be accomplished with a hazard map. One application of hazard maps is to forecast volcanic ashfall following an eruption to help people and organisations prepare themselves for, and mitigate the detrimental impacts of, volcanic ashfall. This research evaluated the key elements of a hazard map and how to make a hazard map most effective through the study of short-term ashfall forecast maps in New Zealand. A mixed-methods approach was taken for this research. Interviews were conducted with scientists at GNS and stakeholders who use the ashfall forecast maps. After the data from the interviews was analysed, an internet-based survey was created and sent out to anyone interested in participating. The survey served as a low-resolution verification of the high-resolution data gathered in the interviews. After each stage of information gathering, the ashfall forecast map design was updated. This research found that there are seven basic elements which should be considered when creating a hazard map. These elements are: simplicity of the map, base map, map scale, the use of colour, geographical information, the inclusion of uncertainty, and time. This research also found key lessons which can be applied to any hazard map creation process. These lessons are: established practices should be revaluated periodically, communication between the information provider and the enduser is critical, the information provider must decide between satisfying the individual or the group, education and outreach are important, audience feedback is necessary for an effective map, and that hazard maps are just one step in the risk mitigation process.

Perturbações ambientais foram detectadas em sistema de turfeira no sul da Bacia do Paraná (Mina de Faxinal, Formação Rio Bonito) durante o Eopermiano (idade radiométrica 291 ± 1.3 Ma, topo do Sakmariano) sob vigência de período climático pós-glacial da Idade do Gelo do Neopaleozoico. Além da detecção de incêndios recorrentes, foi identificado um evento de incêndio autóctone/hipoautóctone em vegetação arbórea em um horizonte no carvão contendo grandes fragmentos de lenhos queimados comprimidos (21,8 x 13.4 cm). A influência de vulcanismo está registrada sob a forma de uma camada de tonstein (cinza vulcânica sedimentada) intercalada ao carvão, onde estão incluídas abundantes compressões de folhas glossopterídeas. A análise do carvão consistiu em determinação de refletância sob óleo de macerais do grupo inertinita em blocos polidos para confirmar a identificação de carvão vegetal macroscópico e ocorrência de incêndios na turfeira. Adicionalmente, a observação da matéria orgânica sob fluorescência nos blocos revelou que os incêndios não afetaram a microflora, mas alteração na fluorescência evidenciou dessecação ambiental, verificada também em lâminas palinofaciológicas. Sob microscopia eletrônica de varredura, o carvão vegetal apresentou paredes celulares homogeneizadas, indicando temperaturas de queima acima de 325ºC, mas não superiores a 400ºC devido aos baixos resultados de refletância e à preservação de tecido vegetal delicado. A preservação de floema secundário, em associação orgânica com xilema tipo Agathoxylon, é registrada ineditamente. A observação sob microscopia de luz transmitida das cutículas foliares extraídas do tonstein permitiu descrição detalhada de padrões xeromórficos que ocorrem de forma endêmica nas epidermes de glossopterídeas de Faxinal e foram atribuídos a respostas adaptativas às frequentes perturbações ambientais que afetaram a floresta turfosa, tais como incêndios recorrentes por dessecação ambiental cíclica ou influência de vulcanismo regional. Esses fatores, em conjunto ou alternativamente, garantiram a dominância monotípica de Glossopteris pubescens nom. nov. na comunidade. O conjunto de evidências indicou que os incêndios foram de superfície, em baixas temperaturas, o transporte do carvão vegetal foi praticamente inexistente no horizonte de grandes fragmentos de lenhos queimados e que os demais incêndios recorrentes tiveram pouco efeito na comunidade proximal, ocorrendo regularmente nas áreas de entorno da turfeira dado o aporte de carvão vegetal macroscópico fragmentário. Durante a fase de aquecimento pós-glacial no Permiano, os ambientes de turfeira no Gondwana eram altamente suscetíveis à ocorrência de incêndios dos quais as glossopterídeas se beneficiavam para manter sua dominância e abundância nessas comunidades, por possuírem eficiente plasticidade adaptativa para sobreviver a condições extremas em ambientes altamente perturbados. / Environmental disturbances were detected in a peat-forming environment from the southern Brazilian Paraná Basin (Faxinal Coalfield, Rio Bonito Formation) during the lower Permian (radiometric age 291 ± 1.3 Ma, late Sakmarian) under post-glacial conditions in the Late Paleozoic Ice Age. In addition to recurrent wildfires, an autochthonous/hypauthochthonous wildfire event was identified in the woody vegetation from a coal horizon containing compressed, large-sized logs (21,8 x 13.4 cm). Volcanic influence is recorded in a tonstein layer (sedimentary volcanic ash) interbedded in the coal, where abundant compressed glossopterid leaves are entombed. The coal analysis consisted of reflectance measurements in polished blocks under oil of macerals of the inertinite group to confirm the macroscopic charcoal identification and wildfire occurrence in the peatland. Additionally, the observation of the organic matter in the polished block under fluorescence showed that the microflora has not been affected by the wildfires, but altered fluorescence evidenced environmental dryness, verified in palynofacies slides as well. Under scannin electron microscopy, the charcoal showed homogenized cell walls, indicating burning temperatures higher than 325ºC, but not higher than 400ºC given the low reflectance values and the preservation of fragile plant tissue. The preservation of secondary phloem in organic association with Agathoxylon wood-type is a first paleobotanical record. Observation under transmitted light of the leaf cuticles extracted from the tonstein allowed for the detailed description of xeromorphic patterns, which have been attributed to adaptative responses to the frequent environmental disturbances affecting the peat forest, such as recurrent wildfires due to environmental dryness or regional volcanic activity. These factors, collectively or in an alternating way, ensured the monotypic dominance of Glossopteris pubescens nom. nov. in the plant community. The set of evidences indicated low temperature surface fires, virtually inexistent charcoal transport in the charcoalified log horizon and that the other wildfire events had little effect in the proximal community, occurring regularly in the surrounding areas of the peatland given the fragmentary macroscopic charcoal input. During the postglacial warming in the Permian, the Gondwanan peatlands were highly susceptible to wildfires from which the glossopterids benefited to maintain their dominance and abundance in these communities due to efficient adaptative plasticity to survive under extreme conditions in highly disturbed environments.

Perturbações ambientais foram detectadas em sistema de turfeira no sul da Bacia do Paraná (Mina de Faxinal, Formação Rio Bonito) durante o Eopermiano (idade radiométrica 291 ± 1.3 Ma, topo do Sakmariano) sob vigência de período climático pós-glacial da Idade do Gelo do Neopaleozoico. Além da detecção de incêndios recorrentes, foi identificado um evento de incêndio autóctone/hipoautóctone em vegetação arbórea em um horizonte no carvão contendo grandes fragmentos de lenhos queimados comprimidos (21,8 x 13.4 cm). A influência de vulcanismo está registrada sob a forma de uma camada de tonstein (cinza vulcânica sedimentada) intercalada ao carvão, onde estão incluídas abundantes compressões de folhas glossopterídeas. A análise do carvão consistiu em determinação de refletância sob óleo de macerais do grupo inertinita em blocos polidos para confirmar a identificação de carvão vegetal macroscópico e ocorrência de incêndios na turfeira. Adicionalmente, a observação da matéria orgânica sob fluorescência nos blocos revelou que os incêndios não afetaram a microflora, mas alteração na fluorescência evidenciou dessecação ambiental, verificada também em lâminas palinofaciológicas. Sob microscopia eletrônica de varredura, o carvão vegetal apresentou paredes celulares homogeneizadas, indicando temperaturas de queima acima de 325ºC, mas não superiores a 400ºC devido aos baixos resultados de refletância e à preservação de tecido vegetal delicado. A preservação de floema secundário, em associação orgânica com xilema tipo Agathoxylon, é registrada ineditamente. A observação sob microscopia de luz transmitida das cutículas foliares extraídas do tonstein permitiu descrição detalhada de padrões xeromórficos que ocorrem de forma endêmica nas epidermes de glossopterídeas de Faxinal e foram atribuídos a respostas adaptativas às frequentes perturbações ambientais que afetaram a floresta turfosa, tais como incêndios recorrentes por dessecação ambiental cíclica ou influência de vulcanismo regional. Esses fatores, em conjunto ou alternativamente, garantiram a dominância monotípica de Glossopteris pubescens nom. nov. na comunidade. O conjunto de evidências indicou que os incêndios foram de superfície, em baixas temperaturas, o transporte do carvão vegetal foi praticamente inexistente no horizonte de grandes fragmentos de lenhos queimados e que os demais incêndios recorrentes tiveram pouco efeito na comunidade proximal, ocorrendo regularmente nas áreas de entorno da turfeira dado o aporte de carvão vegetal macroscópico fragmentário. Durante a fase de aquecimento pós-glacial no Permiano, os ambientes de turfeira no Gondwana eram altamente suscetíveis à ocorrência de incêndios dos quais as glossopterídeas se beneficiavam para manter sua dominância e abundância nessas comunidades, por possuírem eficiente plasticidade adaptativa para sobreviver a condições extremas em ambientes altamente perturbados. / Environmental disturbances were detected in a peat-forming environment from the southern Brazilian Paraná Basin (Faxinal Coalfield, Rio Bonito Formation) during the lower Permian (radiometric age 291 ± 1.3 Ma, late Sakmarian) under post-glacial conditions in the Late Paleozoic Ice Age. In addition to recurrent wildfires, an autochthonous/hypauthochthonous wildfire event was identified in the woody vegetation from a coal horizon containing compressed, large-sized logs (21,8 x 13.4 cm). Volcanic influence is recorded in a tonstein layer (sedimentary volcanic ash) interbedded in the coal, where abundant compressed glossopterid leaves are entombed. The coal analysis consisted of reflectance measurements in polished blocks under oil of macerals of the inertinite group to confirm the macroscopic charcoal identification and wildfire occurrence in the peatland. Additionally, the observation of the organic matter in the polished block under fluorescence showed that the microflora has not been affected by the wildfires, but altered fluorescence evidenced environmental dryness, verified in palynofacies slides as well. Under scannin electron microscopy, the charcoal showed homogenized cell walls, indicating burning temperatures higher than 325ºC, but not higher than 400ºC given the low reflectance values and the preservation of fragile plant tissue. The preservation of secondary phloem in organic association with Agathoxylon wood-type is a first paleobotanical record. Observation under transmitted light of the leaf cuticles extracted from the tonstein allowed for the detailed description of xeromorphic patterns, which have been attributed to adaptative responses to the frequent environmental disturbances affecting the peat forest, such as recurrent wildfires due to environmental dryness or regional volcanic activity. These factors, collectively or in an alternating way, ensured the monotypic dominance of Glossopteris pubescens nom. nov. in the plant community. The set of evidences indicated low temperature surface fires, virtually inexistent charcoal transport in the charcoalified log horizon and that the other wildfire events had little effect in the proximal community, occurring regularly in the surrounding areas of the peatland given the fragmentary macroscopic charcoal input. During the postglacial warming in the Permian, the Gondwanan peatlands were highly susceptible to wildfires from which the glossopterids benefited to maintain their dominance and abundance in these communities due to efficient adaptative plasticity to survive under extreme conditions in highly disturbed environments.

Perturbações ambientais foram detectadas em sistema de turfeira no sul da Bacia do Paraná (Mina de Faxinal, Formação Rio Bonito) durante o Eopermiano (idade radiométrica 291 ± 1.3 Ma, topo do Sakmariano) sob vigência de período climático pós-glacial da Idade do Gelo do Neopaleozoico. Além da detecção de incêndios recorrentes, foi identificado um evento de incêndio autóctone/hipoautóctone em vegetação arbórea em um horizonte no carvão contendo grandes fragmentos de lenhos queimados comprimidos (21,8 x 13.4 cm). A influência de vulcanismo está registrada sob a forma de uma camada de tonstein (cinza vulcânica sedimentada) intercalada ao carvão, onde estão incluídas abundantes compressões de folhas glossopterídeas. A análise do carvão consistiu em determinação de refletância sob óleo de macerais do grupo inertinita em blocos polidos para confirmar a identificação de carvão vegetal macroscópico e ocorrência de incêndios na turfeira. Adicionalmente, a observação da matéria orgânica sob fluorescência nos blocos revelou que os incêndios não afetaram a microflora, mas alteração na fluorescência evidenciou dessecação ambiental, verificada também em lâminas palinofaciológicas. Sob microscopia eletrônica de varredura, o carvão vegetal apresentou paredes celulares homogeneizadas, indicando temperaturas de queima acima de 325ºC, mas não superiores a 400ºC devido aos baixos resultados de refletância e à preservação de tecido vegetal delicado. A preservação de floema secundário, em associação orgânica com xilema tipo Agathoxylon, é registrada ineditamente. A observação sob microscopia de luz transmitida das cutículas foliares extraídas do tonstein permitiu descrição detalhada de padrões xeromórficos que ocorrem de forma endêmica nas epidermes de glossopterídeas de Faxinal e foram atribuídos a respostas adaptativas às frequentes perturbações ambientais que afetaram a floresta turfosa, tais como incêndios recorrentes por dessecação ambiental cíclica ou influência de vulcanismo regional. Esses fatores, em conjunto ou alternativamente, garantiram a dominância monotípica de Glossopteris pubescens nom. nov. na comunidade. O conjunto de evidências indicou que os incêndios foram de superfície, em baixas temperaturas, o transporte do carvão vegetal foi praticamente inexistente no horizonte de grandes fragmentos de lenhos queimados e que os demais incêndios recorrentes tiveram pouco efeito na comunidade proximal, ocorrendo regularmente nas áreas de entorno da turfeira dado o aporte de carvão vegetal macroscópico fragmentário. Durante a fase de aquecimento pós-glacial no Permiano, os ambientes de turfeira no Gondwana eram altamente suscetíveis à ocorrência de incêndios dos quais as glossopterídeas se beneficiavam para manter sua dominância e abundância nessas comunidades, por possuírem eficiente plasticidade adaptativa para sobreviver a condições extremas em ambientes altamente perturbados. / Environmental disturbances were detected in a peat-forming environment from the southern Brazilian Paraná Basin (Faxinal Coalfield, Rio Bonito Formation) during the lower Permian (radiometric age 291 ± 1.3 Ma, late Sakmarian) under post-glacial conditions in the Late Paleozoic Ice Age. In addition to recurrent wildfires, an autochthonous/hypauthochthonous wildfire event was identified in the woody vegetation from a coal horizon containing compressed, large-sized logs (21,8 x 13.4 cm). Volcanic influence is recorded in a tonstein layer (sedimentary volcanic ash) interbedded in the coal, where abundant compressed glossopterid leaves are entombed. The coal analysis consisted of reflectance measurements in polished blocks under oil of macerals of the inertinite group to confirm the macroscopic charcoal identification and wildfire occurrence in the peatland. Additionally, the observation of the organic matter in the polished block under fluorescence showed that the microflora has not been affected by the wildfires, but altered fluorescence evidenced environmental dryness, verified in palynofacies slides as well. Under scannin electron microscopy, the charcoal showed homogenized cell walls, indicating burning temperatures higher than 325ºC, but not higher than 400ºC given the low reflectance values and the preservation of fragile plant tissue. The preservation of secondary phloem in organic association with Agathoxylon wood-type is a first paleobotanical record. Observation under transmitted light of the leaf cuticles extracted from the tonstein allowed for the detailed description of xeromorphic patterns, which have been attributed to adaptative responses to the frequent environmental disturbances affecting the peat forest, such as recurrent wildfires due to environmental dryness or regional volcanic activity. These factors, collectively or in an alternating way, ensured the monotypic dominance of Glossopteris pubescens nom. nov. in the plant community. The set of evidences indicated low temperature surface fires, virtually inexistent charcoal transport in the charcoalified log horizon and that the other wildfire events had little effect in the proximal community, occurring regularly in the surrounding areas of the peatland given the fragmentary macroscopic charcoal input. During the postglacial warming in the Permian, the Gondwanan peatlands were highly susceptible to wildfires from which the glossopterids benefited to maintain their dominance and abundance in these communities due to efficient adaptative plasticity to survive under extreme conditions in highly disturbed environments.

Volcanic eruptions are powerful natural events which impact strongly on society. As human populations grow and expand into volcanically active areas, their exposure and vulnerability to volcanic hazards is also increasing. Of all volcanic hazards, ashfall is the most likely to impact lifelines because of the large areas affected. The widespread dispersal of ash can cause large-scale disruption of vital infrastructure services, aviation, and primary production. Electric power supply is arguably the most crucial of modern infrastructure systems, especially considering the dependence of other sectors on electricity to maintain functionality. During and immediately after ashfalls, electric power systems are vulnerable to a number of impacts, but disruption from volcanic ash-induced insulator flashover (unintended, disruptive electrical discharge) is most common. This thesis investigates the vulnerability of electric power systems to volcanic ashfall by examining impacts to the different sectors of the modern power system and exploring appropriate mitigation strategies. Analogue laboratory trials using a pseudo (synthetic) ash are undertaken to verify the environmental, volcanological and electrical parameters that most affect electrical conductivity and therefore the flashover mechanism in these experiments. While dry ash is highly resistant to the flow of electric current, increasing moisture content, soluble salt load, and compaction (bulk density) will reduce this resistance and, in turn, increase the potential for flashover. Volcanic ash is an acute form of airborne pollution for areas downwind of active volcanoes. Results from laboratory experiments in this thesis suggest that insulator pollution (volcanic ash) performance (dielectric strength) is primarily dictated by (1) the conductivity of the ash, and (2) insulator material, profile (shape) and dimensioning. Composite polymer insulators tested herein effectively minimise sinusoidal leakage current and partial discharge activity and also exhibit higher pollution performance when compared to ceramic equivalents. Irrespective of insulator material, however, the likelihood of flashover increases significantly once the bottom surface of suspension insulator watersheds become contaminated in wet ash. The thesis investigates the vulnerability (hazard intensity/damage ratio) of electric power systems to volcanic ashfall hazards. Identification, analysis, and reduction of the risk of ashfall impacts to power networks is explored as a part of holistic volcanic risk assessment. The findings of the thesis contribute to the readiness, response and recovery protocols for large electric power systems in volcanic disasters; which directly affects the functional operation and economics of industrial and commercial society.