title: The Taupō eruption sequence of AD 232 +- 10 in Aotearoa New Zealand: a retrospection

authors: Lowe, David J.

subjects: Taupō eruption, Taupō supervolcano, eruption Y, non-welded ignimbrite, low-aspect ratio ignimbrite, inverse volcano, pyroclastic flow, density current, plinian, phreatoplinian, radiocarbon wiggle-matching, breakout flood, rhyolite, tephrochronology, tephra, Vitrands, Pumice Soils, volcanic hazard, Taupō Volcanic Zone, gullying, cobalt deficiency, plantation forestry

abstract: The Taupō eruption, also known as eruption Y, occurred in late summer to early autumn (typically late March to early April) in AD 232 +- 10 yr at Taupō volcano, an ‘inverse’ caldera volcano underlying Lake Taupō in the central Taupō Volcanic Zone, North Island, Aotearoa New Zealand. The complex rhyolitic eruption, the most powerful eruption globally in the last 5000 years, lasted between several days and several weeks and generated five markedly contrasting pyroclastic fall deposits (units Y1 to Y5) followed by the extremely violent emplacement of a low-aspect-ratio ignimbrite (unit Y6). The fall deposits include three phreatomagmatic units, Y1, Y3, and Y4, the latter two being the products of archetypal phreatoplinian events; and two magmatic units, Y2 and Y5, the latter being the product of an exceptionally powerful plinian (previously described as ‘ultraplinian’) event with an extreme magma discharge rate around 108 to 1010 kg s-1. The pyroclastic fall-generating eruptions were followed by the climactic emplacement of the entirely nonwelded Taupō ignimbrite (Y6). It was generated by the catastrophic collapse of the 35 to 40-km high plinian eruption column (Y5) that produced a very-fast-moving (600 to 900 km h-1), hot (up to 500 deg C) pyroclastic flow (density current) that covered about 20,000 km2 of central North Island over a near-circular area ~160 km in diameter, centred on Lake Taupō, in fewer than about ten to 15 minutes. This violent ground-hugging pyroclastic flow generated its own air lubrication, forming a near-frictionless basal region, and the resultant highly fluidised ignimbrite was spread as a near-continuous but thin sheet over the entire landscape, both infilling valleys and mantling ridges. Caldera collapse formed a new basin in the older Ōruanui caldera in Lake Taupo. The pressure-wave arising from the plinian-column collapse probably generated a global volcano-meteorological tsunami. Studied intensely by extraordinary volcanologists Colin Wilson and George Walker, and others, the exceptionally well-preserved and readily-accessible Taupō eruptives provide a one-in-a-hundred classic sequence that is arguably the most informative in the global world of volcanology with respect to explosive rhyolitic eruptions and their products. The total volume of the Taupō eruptives amounts to ~35 km3 as magma, equivalent to ~105 km3 of bulk (loose) pyroclastic material, of which the Taupō ignimbrite comprises ~30 km3. The impacts and landscape response of the eruption were profound, spatially extensive, and enduring, and the young glassy soils (Vitrands in Soil Taxonomy, Pumice Soils in the New Zealand Soil Classification) developed in the silica-rich pumiceous deposits, although well suited to plantation forestry (especially exotic Pinus radiata), pose unique problems for agriculture and other land uses, including a high susceptibility to gully erosion and an inherent deficiency in cobalt and other trace elements, and require special management.

text: The Taupō eruption sequence of AD 232 +- 10 in Aotearoa New Zealand: a retrospection The Taupō eruption, also known as eruption Y, occurred in late summer to early autumn (typically late March to early April) in AD 232 +- 10 yr at Taupō volcano, an ‘inverse’ caldera volcano underlying Lake Taupō in the central Taupō Volcanic Zone, North Island, Aotearoa New Zealand. The complex rhyolitic eruption, the most powerful eruption globally in the last 5000 years, lasted between several days and several weeks and generated five markedly contrasting pyroclastic fall deposits (units Y1 to Y5) followed by the extremely violent emplacement of a low-aspect-ratio ignimbrite (unit Y6). The fall deposits include three phreatomagmatic units, Y1, Y3, and Y4, the latter two being the products of archetypal phreatoplinian events; and two magmatic units, Y2 and Y5, the latter being the product of an exceptionally powerful plinian (previously described as ‘ultraplinian’) event with an extreme magma discharge rate around 108 to 1010 kg s-1. The pyroclastic fall-generating eruptions were followed by the climactic emplacement of the entirely nonwelded Taupō ignimbrite (Y6). It was generated by the catastrophic collapse of the 35 to 40-km high plinian eruption column (Y5) that produced a very-fast-moving (600 to 900 km h-1), hot (up to 500 deg C) pyroclastic flow (density current) that covered about 20,000 km2 of central North Island over a near-circular area ~160 km in diameter, centred on Lake Taupō, in fewer than about ten to 15 minutes. This violent ground-hugging pyroclastic flow generated its own air lubrication, forming a near-frictionless basal region, and the resultant highly fluidised ignimbrite was spread as a near-continuous but thin sheet over the entire landscape, both infilling valleys and mantling ridges. Caldera collapse formed a new basin in the older Ōruanui caldera in Lake Taupo. The pressure-wave arising from the plinian-column collapse probably generated a global volcano-meteorological tsunami. Studied intensely by extraordinary volcanologists Colin Wilson and George Walker, and others, the exceptionally well-preserved and readily-accessible Taupō eruptives provide a one-in-a-hundred classic sequence that is arguably the most informative in the global world of volcanology with respect to explosive rhyolitic eruptions and their products. The total volume of the Taupō eruptives amounts to ~35 km3 as magma, equivalent to ~105 km3 of bulk (loose) pyroclastic material, of which the Taupō ignimbrite comprises ~30 km3. The impacts and landscape response of the eruption were profound, spatially extensive, and enduring, and the young glassy soils (Vitrands in Soil Taxonomy, Pumice Soils in the New Zealand Soil Classification) developed in the silica-rich pumiceous deposits, although well suited to plantation forestry (especially exotic Pinus radiata), pose unique problems for agriculture and other land uses, including a high susceptibility to gully erosion and an inherent deficiency in cobalt and other trace elements, and require special management.

year: 2021-02-25

title: The influence of leaders organizational citizenship behaviors and counterproductive work behaviors on employee wellbeing: A multilevel investigation

authors: Roche, Maree A.

abstract: Leader’s organizational citizenship behaviors (OCBs) have been found to directly and indirectly enhance group OCBs, while counter productive work behaviors (CWBs) can have an effect on employee stress and related problems. While previous research has considered these separately, Moral Licensing Theory suggests that those leaders who engage in positive behaviors can feel that they are then able to subsequently engage in negative behaviors. We test the influence of 134 leaders’ on 306 followers job burnout, and find leaders’ self-rated organizational citizenship behaviors (OCBs) were negatively related to follower-rated leaders’ counterproductive work behaviors (CWBs) and followers’ job burnout, and leaders’ CWB were positively related. We also tested and found that CWB interacted with OCBs, which showed that leaders’ who highly engage in positive behaviors still have a positive influence on their followers even when they engage in negative behaviors. Overall, we find empirical support for moral licensing, finding that leaders’ positive behaviors are still most important.

text: The influence of leaders organizational citizenship behaviors and counterproductive work behaviors on employee wellbeing: A multilevel investigation Leader’s organizational citizenship behaviors (OCBs) have been found to directly and indirectly enhance group OCBs, while counter productive work behaviors (CWBs) can have an effect on employee stress and related problems. While previous research has considered these separately, Moral Licensing Theory suggests that those leaders who engage in positive behaviors can feel that they are then able to subsequently engage in negative behaviors. We test the influence of 134 leaders’ on 306 followers job burnout, and find leaders’ self-rated organizational citizenship behaviors (OCBs) were negatively related to follower-rated leaders’ counterproductive work behaviors (CWBs) and followers’ job burnout, and leaders’ CWB were positively related. We also tested and found that CWB interacted with OCBs, which showed that leaders’ who highly engage in positive behaviors still have a positive influence on their followers even when they engage in negative behaviors. Overall, we find empirical support for moral licensing, finding that leaders’ positive behaviors are still most important.

year: 2015

title: The cultural perspective: Lakeweed and pest animals

authors: Douglas, Nicki

abstract: I have been with the Department of Conservation for about 15 years now and worked in Rotorua for 11 of those 15 years in various roles. I was lucky enough to be the Operations Manager for Lake Tarawera so I have a very strong association from a practitioner perspective. Practitioner is probably the key word for me. Most of my korero today will be based on experience and practice in working with communities and that is my area of expertise. I will talk about collective impact. It does say that I am talking about lake weeds and pests and I will mention them at least twice.

text: The cultural perspective: Lakeweed and pest animals I have been with the Department of Conservation for about 15 years now and worked in Rotorua for 11 of those 15 years in various roles. I was lucky enough to be the Operations Manager for Lake Tarawera so I have a very strong association from a practitioner perspective. Practitioner is probably the key word for me. Most of my korero today will be based on experience and practice in working with communities and that is my area of expertise. I will talk about collective impact. It does say that I am talking about lake weeds and pests and I will mention them at least twice.

year: 2017