title: Estimating pre-historic earthquake parameters in the Hamilton lowlands using laboratory geotechnical analyses of seismically liquefied volcanic-ash layers in lakes

authors: Chaneva, Jordanka

abstract: Soft-sediment deformation structures caused by pre-historic earthquakes were discovered in volcanicash (tephra) units preserved as discrete layers within soft, organic lake sediments in the Hamilton lowlands, North Island, New Zealand. Complementing a broader paleoliquefaction project that involves geological and seismological perspectives as well, this PhD research was focused on a geotechnical approach in analysing the paleoliquefaction features in the tephra layers across multiple 20 cal-ka-aged lakes in the Hamilton lowlands. Aiming to back-analyse pre-historic earthquakes that might have caused the palaeoliquefaction features, this thesis also had to address literature and knowledge gaps related to cyclic undrained behaviour and liquefaction resistance of pumiceous silts and sand-silt mixtures. Thus, the scope of this research covered the following objectives: (1) analyses of the geotechnical properties of the tephras of interest in order to define their liquefaction susceptibility, (2) investigation of the undrained monotonic and cyclic behaviour of a pumiceous silt (Tuhua silt, from lacustrine Tuhua tephra aged 7.6 cal ka) in order to fill knowledge gaps related to potential particle crushing affecting undrained cyclic behaviour as well as liquefaction resistance in pumiceous silts, (3) identification of the potential threshold of pumice content and/or fines content, at which pumiceous sand-silt mixtures (internal beds from lacustrine Mamaku tephra aged 8.0 cal ka) become crushable, and finally (4) developing a framework, that extends laboratory obtained liquefaction resistance ratios of three different beds of one of the tephras of interest, that provided enough volume for cyclic undrained triaxial testing (Mamaku tephra), into the rest of the tephras across the studied lakes (that only provided small volumes for sampling). The last objective assisted in reaching the main aim of this thesis which was to obtain the equivalent triggering earthquake parameters, i.e., peak ground acceleration, amax and earthquake magnitude, M for the tephras across the lakes, based on their estimated liquefaction resistances. It was found that the tephras in the lakes are pumiceous and liquefiable within the grain-size range: silts to sandy silts to silty sands. The results from undrained triaxial testing on the pumiceous silt showed that no particle crushing occurred and that the silty material behaved closer to the typical trends established for hard-grained soils than to those associated with pumiceous sands. Furthermore, the undrained cyclic triaxial testing program on three different beds, one silt and two silty sands, from one of the tephras of interest (Mamaku tephra), suggested a fines threshold below which begin to crush during cyclic triaxial testing to be somewhere between 31% and 20%. Empirical correlations used to estimate earthquake parameters from liquefaction resistance that are derived for hard-grained soils were, thus, considered reasonable for application to the pumiceous materials considered in the current study. The final results of this study showed that the tephra layers across the lakes were very sensitive and vulnerable to liquefaction at very low peak ground accelerations, i.e. amax ranging from 0.02 to 0.08 g within the range of magnitudes, M = 5 to 8.5. The high vulnerability to liquefaction across all the Mamaku tephra layers in the Hamilton lowlands (~13 lakes) was considered to be the result of the very low in-situ overburden stresses, consequence of their shallow burial depths in the lake environment, as well as the relatively low liquefaction resistance in situ. The results presented in this dissertation, (1) supply valuable information about the liquefaction potential of pre-historically liquefied tephra layers, assisting local paleoliquefaction studies in the Hamilton lowlands area, (2) explore the possibility of applying laboratory-based liquefaction resistance analysis in paleoliquefaction studies, and (3) contribute to better understanding of the undrained behaviour and liquefaction resistance of pumiceous sand-silt mixtures.

text: Estimating pre-historic earthquake parameters in the Hamilton lowlands using laboratory geotechnical analyses of seismically liquefied volcanic-ash layers in lakes Soft-sediment deformation structures caused by pre-historic earthquakes were discovered in volcanicash (tephra) units preserved as discrete layers within soft, organic lake sediments in the Hamilton lowlands, North Island, New Zealand. Complementing a broader paleoliquefaction project that involves geological and seismological perspectives as well, this PhD research was focused on a geotechnical approach in analysing the paleoliquefaction features in the tephra layers across multiple 20 cal-ka-aged lakes in the Hamilton lowlands. Aiming to back-analyse pre-historic earthquakes that might have caused the palaeoliquefaction features, this thesis also had to address literature and knowledge gaps related to cyclic undrained behaviour and liquefaction resistance of pumiceous silts and sand-silt mixtures. Thus, the scope of this research covered the following objectives: (1) analyses of the geotechnical properties of the tephras of interest in order to define their liquefaction susceptibility, (2) investigation of the undrained monotonic and cyclic behaviour of a pumiceous silt (Tuhua silt, from lacustrine Tuhua tephra aged 7.6 cal ka) in order to fill knowledge gaps related to potential particle crushing affecting undrained cyclic behaviour as well as liquefaction resistance in pumiceous silts, (3) identification of the potential threshold of pumice content and/or fines content, at which pumiceous sand-silt mixtures (internal beds from lacustrine Mamaku tephra aged 8.0 cal ka) become crushable, and finally (4) developing a framework, that extends laboratory obtained liquefaction resistance ratios of three different beds of one of the tephras of interest, that provided enough volume for cyclic undrained triaxial testing (Mamaku tephra), into the rest of the tephras across the studied lakes (that only provided small volumes for sampling). The last objective assisted in reaching the main aim of this thesis which was to obtain the equivalent triggering earthquake parameters, i.e., peak ground acceleration, amax and earthquake magnitude, M for the tephras across the lakes, based on their estimated liquefaction resistances. It was found that the tephras in the lakes are pumiceous and liquefiable within the grain-size range: silts to sandy silts to silty sands. The results from undrained triaxial testing on the pumiceous silt showed that no particle crushing occurred and that the silty material behaved closer to the typical trends established for hard-grained soils than to those associated with pumiceous sands. Furthermore, the undrained cyclic triaxial testing program on three different beds, one silt and two silty sands, from one of the tephras of interest (Mamaku tephra), suggested a fines threshold below which begin to crush during cyclic triaxial testing to be somewhere between 31% and 20%. Empirical correlations used to estimate earthquake parameters from liquefaction resistance that are derived for hard-grained soils were, thus, considered reasonable for application to the pumiceous materials considered in the current study. The final results of this study showed that the tephra layers across the lakes were very sensitive and vulnerable to liquefaction at very low peak ground accelerations, i.e. amax ranging from 0.02 to 0.08 g within the range of magnitudes, M = 5 to 8.5. The high vulnerability to liquefaction across all the Mamaku tephra layers in the Hamilton lowlands (~13 lakes) was considered to be the result of the very low in-situ overburden stresses, consequence of their shallow burial depths in the lake environment, as well as the relatively low liquefaction resistance in situ. The results presented in this dissertation, (1) supply valuable information about the liquefaction potential of pre-historically liquefied tephra layers, assisting local paleoliquefaction studies in the Hamilton lowlands area, (2) explore the possibility of applying laboratory-based liquefaction resistance analysis in paleoliquefaction studies, and (3) contribute to better understanding of the undrained behaviour and liquefaction resistance of pumiceous sand-silt mixtures.

year: 2024

title: Differential-Stäckel matrices

authors: Kalnins, Ernie G.

subjects: Mathematics

abstract: We show that additive separation of variables for linear homogeneous equations of all orders is characterized by differential-Stäckel matrices, generalizations of the classical Stäckel matrices used for multiplicative separation of (second-order) Schrödinger equations and additive separation of Hamilton–Jacobi equations. We work out the principal properties of these matrices and demonstrate that even for second-order Laplace equations additive separation may occur when multiplicative separation does not.

text: Differential-Stäckel matrices We show that additive separation of variables for linear homogeneous equations of all orders is characterized by differential-Stäckel matrices, generalizations of the classical Stäckel matrices used for multiplicative separation of (second-order) Schrödinger equations and additive separation of Hamilton–Jacobi equations. We work out the principal properties of these matrices and demonstrate that even for second-order Laplace equations additive separation may occur when multiplicative separation does not.

year: 1985-07

title: Mouri Tu, Mouri Moko, Mouri Ora! Moko as a wellbeing strategy

authors: Penehira, Mera

subjects: Maori

abstract: This research has been undertaken within the Health Research Council funded International Collaborative Indigenous Health Research Partnership (ICIHRP) program, “The role of resiliency in responding to blood borne viral and sexually transmitted infections in Indigenous communities”. Some Indigenous communities in Australia, New Zealand and Canada have been shown to experience higher rates of blood borne viral infections. There are a number of categories of health intervention that have been shown to be effective in prevention and enhancing access to treatment for blood borne viral infections, including various forms of health promotion, enhanced diagnostic and treatment services, and harm reduction measures related to injecting drug use. The present research was undertaken with the understanding that development of effective responses of this kind among Indigenous people would benefit from a better understanding of the social and cultural factors that might protect against these infections and their consequences. It is argued that such factors are linked in various ways to Indigenous resistance and resiliency, which is described as the means by which people choose to make use of individual and community strengths to protect themselves against adverse health outcomes and enhance their health and wellbeing.

In this thesis I explore how people and their identity are affected when you are part of a marginalised or vulnerable population – namely, Māori women who have contracted the Hepatitis C Virus (HCV). I argue that traditional knowledge and healing practices are central to Māori getting well and keeping well, and that the use of cultural frameworks and practices have potentially restorative, therapeutic and healing values that are not yet researched or understood by the health field. I argue that a Māori framework of wellbeing, namely ‘Mana Kaitiakitanga’, provides the context in which tā moko (Māori traditional tattoo) fits naturally as a healing intervention. I share the stories of Māori women with HCV who have applied this (tā moko and other forms of tattoo) in their lives and in their journeys back to wellness. Tā moko is a process that penetrates the flesh and marks the skin; it is a process that involves both blood and pain, which may seem incongruous with healing. It is argued however that through pain comes understanding; through pain comes a RE-membering of strength; through pain comes joy; and finally through marking comes identity of who we are and how well we have been and can be again.

Issues and intersections of identity, marginalisation, gender, health, and wellbeing are at the forefront of this research story and of the journeys of the three women whose case studies are presented in this thesis. What makes this thesis unique is that it researches all three of these potential cornerstones of health: identity; wellbeing (spiritual and emotional), and physical wellbeing, in relation to a specific health problem, namely HCV. It is intended that this work will add power to what might be viewed as a particularly Indigenous solution to a virus that disproportionately affects our Indigenous population. This is not about rejecting Western health solutions, but it is about recognising and returning to Indigenous health solutions.

text: Mouri Tu, Mouri Moko, Mouri Ora! Moko as a wellbeing strategy This research has been undertaken within the Health Research Council funded International Collaborative Indigenous Health Research Partnership (ICIHRP) program, “The role of resiliency in responding to blood borne viral and sexually transmitted infections in Indigenous communities”. Some Indigenous communities in Australia, New Zealand and Canada have been shown to experience higher rates of blood borne viral infections. There are a number of categories of health intervention that have been shown to be effective in prevention and enhancing access to treatment for blood borne viral infections, including various forms of health promotion, enhanced diagnostic and treatment services, and harm reduction measures related to injecting drug use. The present research was undertaken with the understanding that development of effective responses of this kind among Indigenous people would benefit from a better understanding of the social and cultural factors that might protect against these infections and their consequences. It is argued that such factors are linked in various ways to Indigenous resistance and resiliency, which is described as the means by which people choose to make use of individual and community strengths to protect themselves against adverse health outcomes and enhance their health and wellbeing.

In this thesis I explore how people and their identity are affected when you are part of a marginalised or vulnerable population – namely, Māori women who have contracted the Hepatitis C Virus (HCV). I argue that traditional knowledge and healing practices are central to Māori getting well and keeping well, and that the use of cultural frameworks and practices have potentially restorative, therapeutic and healing values that are not yet researched or understood by the health field. I argue that a Māori framework of wellbeing, namely ‘Mana Kaitiakitanga’, provides the context in which tā moko (Māori traditional tattoo) fits naturally as a healing intervention. I share the stories of Māori women with HCV who have applied this (tā moko and other forms of tattoo) in their lives and in their journeys back to wellness. Tā moko is a process that penetrates the flesh and marks the skin; it is a process that involves both blood and pain, which may seem incongruous with healing. It is argued however that through pain comes understanding; through pain comes a RE-membering of strength; through pain comes joy; and finally through marking comes identity of who we are and how well we have been and can be again.

Issues and intersections of identity, marginalisation, gender, health, and wellbeing are at the forefront of this research story and of the journeys of the three women whose case studies are presented in this thesis. What makes this thesis unique is that it researches all three of these potential cornerstones of health: identity; wellbeing (spiritual and emotional), and physical wellbeing, in relation to a specific health problem, namely HCV. It is intended that this work will add power to what might be viewed as a particularly Indigenous solution to a virus that disproportionately affects our Indigenous population. This is not about rejecting Western health solutions, but it is about recognising and returning to Indigenous health solutions.

year: 2011