title: Geomorphic development of White Island Volcano based on slope stability modelling

authors: Moon, Vicki G.

subjects: White Island

abstract: White Island shows many geomorphic features associated with stratovolcanoes that have undergone major sector collapse, most notably the flat-floored amphitheatre comprising the present crater. ArcGIS is used to develop a reconstructed pre-failure cone and 2D limiting-equilibrium stability analysis is undertaken of the reconstructed cone. Water table ranges from 0% (dry) to 100% (saturated) are assumed and earthquake accelerations of 0–0.5 g bracket the likely range of accelerations expected in a volcanic setting; geotechnical data from Moon et al. [Moon, V., Bradshaw, J., Smith, R. and de Lange, W., 2005. Geotechnical characterization of stratocone crater wall sequences, White Island Volcano, New Zealand. Engineering Geology, 81: 146–178] are used. The models suggest that flank failure is a feasible explanation for the present-day geomorphology, and indicate that there were at least two retrogressive failures. The best model sees a core of hydrothermally altered material overlying relatively unaltered andesite lavas and breccias, where accelerations of 0.17 g (saturated slope) to 0.45 g (dry slope) are required to initiate failure (F = 1.0). The failure modelled was relatively small (volume of 0.21 km3), and would have mostly involved hydrothermally altered materials with some fresh rock mass. Two toreva blocks are recognised occupying the seaward margin of the amphitheatre, with a lobe of debris offshore suggested as the debris avalanche deposits. Modification of both the outer slopes of the island and the inner crater walls has occurred since the failure event, especially on the southwestern margin of the crater. Modelling suggests that further failure of the inner walls is likely and poses a significant hazard to tourists visiting the island; further outer slope failures are unlikely.

text: Geomorphic development of White Island Volcano based on slope stability modelling White Island shows many geomorphic features associated with stratovolcanoes that have undergone major sector collapse, most notably the flat-floored amphitheatre comprising the present crater. ArcGIS is used to develop a reconstructed pre-failure cone and 2D limiting-equilibrium stability analysis is undertaken of the reconstructed cone. Water table ranges from 0% (dry) to 100% (saturated) are assumed and earthquake accelerations of 0–0.5 g bracket the likely range of accelerations expected in a volcanic setting; geotechnical data from Moon et al. [Moon, V., Bradshaw, J., Smith, R. and de Lange, W., 2005. Geotechnical characterization of stratocone crater wall sequences, White Island Volcano, New Zealand. Engineering Geology, 81: 146–178] are used. The models suggest that flank failure is a feasible explanation for the present-day geomorphology, and indicate that there were at least two retrogressive failures. The best model sees a core of hydrothermally altered material overlying relatively unaltered andesite lavas and breccias, where accelerations of 0.17 g (saturated slope) to 0.45 g (dry slope) are required to initiate failure (F = 1.0). The failure modelled was relatively small (volume of 0.21 km3), and would have mostly involved hydrothermally altered materials with some fresh rock mass. Two toreva blocks are recognised occupying the seaward margin of the amphitheatre, with a lobe of debris offshore suggested as the debris avalanche deposits. Modification of both the outer slopes of the island and the inner crater walls has occurred since the failure event, especially on the southwestern margin of the crater. Modelling suggests that further failure of the inner walls is likely and poses a significant hazard to tourists visiting the island; further outer slope failures are unlikely.

year: 2009

title: Uptake of ΣDDT, arsenic, cadmium, copper, and lead by lettuce and radish grown in contaminated horticultural soils

authors: Gaw, Sally K.

subjects: horticultural soil

abstract: Horticultural soils can contain elevated concentrations of selected trace elements and organochlorine pesticides as a result of long-term use of agrichemicals and soil amendments. A glasshouse study was undertaken to assess the uptake of weathered ΣDDT {sum of the p,p′- and o,p-isomers of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] and DDD[1,1-dichloro-2,2-bis(p-chlorophenyl)ethane]}, arsenic (As), cadmium (Cd), copper (Cu), and lead (Pb) residues by lettuce (Lactuca sativa) and radish (Raphanus sativus) from field-aged New Zealand horticultural soils. Concentrations of ΣDDT, DDT, DDE, Cd, Cu, and Pb in lettuce increased with increasing soil concentrations. In radish, similar relationships were observed for ΣDDT, DDE, and Cu. The bioaccumulation factors were less than 1 with the exception of Cd and decreased with increasing soil concentrations. Lettuce Cd concentrations for plants grown on four out of 10 assayed soils were equivalent to or exceeded the New Zealand food standard for leafy vegetables of 0.1 mg kg−1 fresh weight. Concentrations of As, Pb, and ΣDDT did not exceed available food standards. Overall, these results demonstrate that aged residues of ΣDDT, As, Cd, Cu, and Pb in horticultural soils have remained phytoavailable. To be protective of human health, site-specific risk assessments and soil guideline derivations for residential settings with vegetable gardens need to consider the produce consumption pathway.

text: Uptake of ΣDDT, arsenic, cadmium, copper, and lead by lettuce and radish grown in contaminated horticultural soils Horticultural soils can contain elevated concentrations of selected trace elements and organochlorine pesticides as a result of long-term use of agrichemicals and soil amendments. A glasshouse study was undertaken to assess the uptake of weathered ΣDDT {sum of the p,p′- and o,p-isomers of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] and DDD[1,1-dichloro-2,2-bis(p-chlorophenyl)ethane]}, arsenic (As), cadmium (Cd), copper (Cu), and lead (Pb) residues by lettuce (Lactuca sativa) and radish (Raphanus sativus) from field-aged New Zealand horticultural soils. Concentrations of ΣDDT, DDT, DDE, Cd, Cu, and Pb in lettuce increased with increasing soil concentrations. In radish, similar relationships were observed for ΣDDT, DDE, and Cu. The bioaccumulation factors were less than 1 with the exception of Cd and decreased with increasing soil concentrations. Lettuce Cd concentrations for plants grown on four out of 10 assayed soils were equivalent to or exceeded the New Zealand food standard for leafy vegetables of 0.1 mg kg−1 fresh weight. Concentrations of As, Pb, and ΣDDT did not exceed available food standards. Overall, these results demonstrate that aged residues of ΣDDT, As, Cd, Cu, and Pb in horticultural soils have remained phytoavailable. To be protective of human health, site-specific risk assessments and soil guideline derivations for residential settings with vegetable gardens need to consider the produce consumption pathway.

year: 2008

title: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest

authors: Martin, Jessica

abstract: On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

text: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

year: 2024-05-16