title: Eruption and emplacement of the 1.3-Ma Ongatiti Ignimbrite, New Zealand:  Regional pathways, particle processes, and pumice evolution associated with a large-volume pyroclastic flow deposit

authors: Yousef Zadeh, Elham

abstract: Pyroclastic flows are the most devastating phenomena of explosive volcanic eruptions. These hazardous density currents are able to travel several tens of kilometers radially away from their source as fast, hot density currents. Due to the enveloping ash cloud, it is still impossible to directly study pyroclastic flows, however, their deposits (i.e. ignimbrites) provide useful insight into their internal processes.

The Ongatiti Ignimbrite was sourced from Mangakino caldera (1600-950 ka), the oldest volcanic center in the Taupo Volcanic Zone, North Island, New Zealand. The crystal- and pumice-rich ignimbrite offers a unique opportunity to understand an ancient and large-volume pyroclastic flow as well as more details about particle processes and pumice evolution. The minimum deposit volume for the Ongatiti Ignimbrite has been revised to approximately 720 km³, or 512 km³ dense rock equivalent. Previous studies proposed ages from 1.21 to 1.28 Ma by dating methods, such as ⁴⁰Ar/³⁹Ar, K/Ar, and zircon fission-track. This research used the (U-Th)/He method to determine an age of 1.3 Ma. 

This study has combined field facies analysis and GIS methods to characterize the Ongatiti Ignimbrite. The topographic controls on the spatial distribution of the ignimbrite has been determined to understand pyroclastic flow pathways through valleys and over hills. The Ongatiti Ignimbrite was a landscape-modifying event that covered at least the western North Island and as far away as Auckland and Wellington. It is a welded to non-welded, columnar-jointed, cliff-forming deposit, that has been divided into nine facies based on the variation in pumice and lithic clast abundance, and welding rank. 
This study also focuses on the texture and components of the ignimbrite matrix to better understand the magma fragmentation process, the transportational and depositional dynamics of the gas-ash fluid, and the post-emplacement processes. The microtextures of ignimbrite matrix were described and quantified by using optical microscopy, scanning electron microscopy, synchrotron x-ray microtomography, electron probe microanalysis, and X-ray powder diffraction (XRD).
The matrix is poorly sorted and varies in the size and texture of ash-sized pumice fragments, glass shards, crystals, and lithic clasts. Glass shards range in shape between dominantly platy, Y-shaped, and complex shapes, and in size from a few microns to about 900 microns. The matrix is crystal-rich and comprises primary subhedral to anhedral volcanic crystals (plagioclase, quartz, pyroxene, hornblende, and Ti-Fe oxides and range between 100 to a few 1000 microns in size. The degree of welding in the matrix is defined by crystal-crystal contacts and deformation of glass shards around particles, and the highest degree of welding is shown by moderately deformed shards. 
The physical characteristics and chemical composition of pumice clasts were determined, and the main pumice textures were recognised as vesicular, fibrous, microvesicular and dense type.  Tomographic imaging shows different vesicularities and local crystal arrangement within pumice and ignimbrite. Glass chemical analysis shows two different groups, higher-silica (~80-81 wt%), and high-silica (76-78 wt%). 
The Ongatiti Ignimbrite was emplaced by a super-eruption with a volcanic explosivity index (VEI) of 7, and eruptions of similar size could catastrophically bury a vast area of the North Island. The matrix of the Ongatiti Ignimbrite suggests complex particle interactions within the ash-gas fluid of pyroclastic flows. Microtomographic imaging of ignimbrite components offers new insights into understanding these complex processes.

text: Eruption and emplacement of the 1.3-Ma Ongatiti Ignimbrite, New Zealand:  Regional pathways, particle processes, and pumice evolution associated with a large-volume pyroclastic flow deposit Pyroclastic flows are the most devastating phenomena of explosive volcanic eruptions. These hazardous density currents are able to travel several tens of kilometers radially away from their source as fast, hot density currents. Due to the enveloping ash cloud, it is still impossible to directly study pyroclastic flows, however, their deposits (i.e. ignimbrites) provide useful insight into their internal processes.

The Ongatiti Ignimbrite was sourced from Mangakino caldera (1600-950 ka), the oldest volcanic center in the Taupo Volcanic Zone, North Island, New Zealand. The crystal- and pumice-rich ignimbrite offers a unique opportunity to understand an ancient and large-volume pyroclastic flow as well as more details about particle processes and pumice evolution. The minimum deposit volume for the Ongatiti Ignimbrite has been revised to approximately 720 km³, or 512 km³ dense rock equivalent. Previous studies proposed ages from 1.21 to 1.28 Ma by dating methods, such as ⁴⁰Ar/³⁹Ar, K/Ar, and zircon fission-track. This research used the (U-Th)/He method to determine an age of 1.3 Ma. 

This study has combined field facies analysis and GIS methods to characterize the Ongatiti Ignimbrite. The topographic controls on the spatial distribution of the ignimbrite has been determined to understand pyroclastic flow pathways through valleys and over hills. The Ongatiti Ignimbrite was a landscape-modifying event that covered at least the western North Island and as far away as Auckland and Wellington. It is a welded to non-welded, columnar-jointed, cliff-forming deposit, that has been divided into nine facies based on the variation in pumice and lithic clast abundance, and welding rank. 
This study also focuses on the texture and components of the ignimbrite matrix to better understand the magma fragmentation process, the transportational and depositional dynamics of the gas-ash fluid, and the post-emplacement processes. The microtextures of ignimbrite matrix were described and quantified by using optical microscopy, scanning electron microscopy, synchrotron x-ray microtomography, electron probe microanalysis, and X-ray powder diffraction (XRD).
The matrix is poorly sorted and varies in the size and texture of ash-sized pumice fragments, glass shards, crystals, and lithic clasts. Glass shards range in shape between dominantly platy, Y-shaped, and complex shapes, and in size from a few microns to about 900 microns. The matrix is crystal-rich and comprises primary subhedral to anhedral volcanic crystals (plagioclase, quartz, pyroxene, hornblende, and Ti-Fe oxides and range between 100 to a few 1000 microns in size. The degree of welding in the matrix is defined by crystal-crystal contacts and deformation of glass shards around particles, and the highest degree of welding is shown by moderately deformed shards. 
The physical characteristics and chemical composition of pumice clasts were determined, and the main pumice textures were recognised as vesicular, fibrous, microvesicular and dense type.  Tomographic imaging shows different vesicularities and local crystal arrangement within pumice and ignimbrite. Glass chemical analysis shows two different groups, higher-silica (~80-81 wt%), and high-silica (76-78 wt%). 
The Ongatiti Ignimbrite was emplaced by a super-eruption with a volcanic explosivity index (VEI) of 7, and eruptions of similar size could catastrophically bury a vast area of the North Island. The matrix of the Ongatiti Ignimbrite suggests complex particle interactions within the ash-gas fluid of pyroclastic flows. Microtomographic imaging of ignimbrite components offers new insights into understanding these complex processes.

year: 2020

title: Biodegradation of bloodmeal-based thermoplastics in green-waste composting

authors: Verbeek, Casparus Johan R.

subjects: bloodmeal

abstract: Polymers that are compostable and manufactured from renewable resources have gained significant importance in recent years. The objective of this work was to assess the biodegradability of bloodmeal-based thermoplastics in a commercial green-waste composting situation. Materials plasticised with tri-ethylene–glycol lost about 45% of their original mass after 12 weeks composting while unplasticised samples lost 35%. Degradation appeared to have been in two phases; an initial loss of soluble, low molecular compounds in the mesophilic phase followed by degradation of high molecular compounds as the temperature exceeded about 40 °C in the thermophilic phase. It was found that as degradation proceeded materials became more soluble. In addition, plasticised and unplasticized samples contained about 60 wt% moisture after 4 weeks of composting conditioning at 50% relative humidity resulted in approximately 8–10 wt% moisture, unaffected by the extent of degradation. FTIR revealed that proteins underwent hydrolytic cleavage resulting in the formation of primary amines. A significant reduction in combustion temperature was observed, indicative of a reduction in covalent bonding, likely due to shorter chains lengths or less cross-linking.

text: Biodegradation of bloodmeal-based thermoplastics in green-waste composting Polymers that are compostable and manufactured from renewable resources have gained significant importance in recent years. The objective of this work was to assess the biodegradability of bloodmeal-based thermoplastics in a commercial green-waste composting situation. Materials plasticised with tri-ethylene–glycol lost about 45% of their original mass after 12 weeks composting while unplasticised samples lost 35%. Degradation appeared to have been in two phases; an initial loss of soluble, low molecular compounds in the mesophilic phase followed by degradation of high molecular compounds as the temperature exceeded about 40 °C in the thermophilic phase. It was found that as degradation proceeded materials became more soluble. In addition, plasticised and unplasticized samples contained about 60 wt% moisture after 4 weeks of composting conditioning at 50% relative humidity resulted in approximately 8–10 wt% moisture, unaffected by the extent of degradation. FTIR revealed that proteins underwent hydrolytic cleavage resulting in the formation of primary amines. A significant reduction in combustion temperature was observed, indicative of a reduction in covalent bonding, likely due to shorter chains lengths or less cross-linking.

year: 2011

title: Manaakitia te paharakeke: an insight into the daily operational challenges facing Te Whakaruruhau

authors: Kurei, Anna

subjects: Women's refuge

abstract: This report is based on participant observations of the daily operations at Te Whakaruruhau, Hamilton. The observations represent the fieldwork element of an undergraduate paper contributing to the co-author, Anna Kurei’s Bachelor’s degree at the University of Waikato. Anna’s participation and observations over several weeks included attending meetings, shadowing Advocates, contributing (as appropriate) to operations and observing interactions between Advocates and the women in living in the service’s residential housing. 
Founded by Ruahine Albert and Ariana Simpson in 1986, Te Whakaruruhau Incorporated (Waikato women's refuge) was the first Māori women's refuge in Aotearoa. Since its inception, Te Whakaruruhau has been a Kaupapa driven service, with Māori cultural practices consciously employed throughout all its operations. Māori tikanga is fluid and adaptable by nature and can therefore meet the needs of people from multiple cultures and backgrounds. The current service has grown from humble beginnings in a four-bedroom state owned house providing emergency housing, to now include a twenty-four-hour crisis service, residential housing and a broadened community outreach programme. Staff numbers have increased from 7 to 36 paid staff and the twenty-fourhour crisis service has allowed the refuge to provide services for high risk cases that would otherwise be turned away. 
Funding is critical to the successful operation of the service. The refuge provides wrap-around services to meet clients’ needs and help them navigate through a maze of government and community services. The needs of women and families who have lived with domestic violence are deep-seated and complex. Achieving a stable, healthy, independent life is frequently a long-term process. Funding however, is not only limited, but is tied to expectations of achieving successful outcomes in the short-term. It was quickly evident during the fieldwork that Te Whakaruruhau is desperately under-resourced. In the year to June 2015 the Refuge provided services for 6575 cases, but had contracted funds for less than 1600. The consequences of such starkly inadequate resources are dire – for both clients and staff.
Advocates (case workers) are frequently exhausted as they try to assist women and children with high and complex needs with very little resources on a highly restricted budget. Many times, workers were observed relegating their own interests (including their own health and safety) in order to meet the demands and needs of their clients. Similarly, the successful rehabilitation of clients is jeopardised by restricted options, insufficient capacity in the system and at times even the simplest of requirements such as transport to essential services. We know that when women and children become free of violence they have better health, employment and education outcomes. These outcomes benefit not only themselves but their communities and the wider social and economic landscape. Higher levels of funding - with a longer term focus- would therefore ultimately reduce the costs of domestic violence overall. Further to this, Kaupapa-based services at Te Whakaruruhau offer a culturally meaningful response to the high representation of Maori women seeking assistance. Its success in the face of such high levels of under-resourcing suggests that expectations around funding also need to be altered.

text: Manaakitia te paharakeke: an insight into the daily operational challenges facing Te Whakaruruhau This report is based on participant observations of the daily operations at Te Whakaruruhau, Hamilton. The observations represent the fieldwork element of an undergraduate paper contributing to the co-author, Anna Kurei’s Bachelor’s degree at the University of Waikato. Anna’s participation and observations over several weeks included attending meetings, shadowing Advocates, contributing (as appropriate) to operations and observing interactions between Advocates and the women in living in the service’s residential housing. 
Founded by Ruahine Albert and Ariana Simpson in 1986, Te Whakaruruhau Incorporated (Waikato women's refuge) was the first Māori women's refuge in Aotearoa. Since its inception, Te Whakaruruhau has been a Kaupapa driven service, with Māori cultural practices consciously employed throughout all its operations. Māori tikanga is fluid and adaptable by nature and can therefore meet the needs of people from multiple cultures and backgrounds. The current service has grown from humble beginnings in a four-bedroom state owned house providing emergency housing, to now include a twenty-four-hour crisis service, residential housing and a broadened community outreach programme. Staff numbers have increased from 7 to 36 paid staff and the twenty-fourhour crisis service has allowed the refuge to provide services for high risk cases that would otherwise be turned away. 
Funding is critical to the successful operation of the service. The refuge provides wrap-around services to meet clients’ needs and help them navigate through a maze of government and community services. The needs of women and families who have lived with domestic violence are deep-seated and complex. Achieving a stable, healthy, independent life is frequently a long-term process. Funding however, is not only limited, but is tied to expectations of achieving successful outcomes in the short-term. It was quickly evident during the fieldwork that Te Whakaruruhau is desperately under-resourced. In the year to June 2015 the Refuge provided services for 6575 cases, but had contracted funds for less than 1600. The consequences of such starkly inadequate resources are dire – for both clients and staff.
Advocates (case workers) are frequently exhausted as they try to assist women and children with high and complex needs with very little resources on a highly restricted budget. Many times, workers were observed relegating their own interests (including their own health and safety) in order to meet the demands and needs of their clients. Similarly, the successful rehabilitation of clients is jeopardised by restricted options, insufficient capacity in the system and at times even the simplest of requirements such as transport to essential services. We know that when women and children become free of violence they have better health, employment and education outcomes. These outcomes benefit not only themselves but their communities and the wider social and economic landscape. Higher levels of funding - with a longer term focus- would therefore ultimately reduce the costs of domestic violence overall. Further to this, Kaupapa-based services at Te Whakaruruhau offer a culturally meaningful response to the high representation of Maori women seeking assistance. Its success in the face of such high levels of under-resourcing suggests that expectations around funding also need to be altered.

year: 2016