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Item Characteristics of volcanic ash soils of southern area of Mount Ruapehu, North Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Soil Science at Massey University(Massey University, 1998) Suryaningtyas, Dyah TjahyandariGeochemical and pedological properties of five volcanic soils were examined to characterise the effects of weathering. The five soils studied are from the southern area of Mount Ruapehu, New Zealand. The principal parent materials are rhyolitic and andesitic tephras. Soils examined in this study are characterised by thick and dark A horizons, crumb and nut structure, and sandy to clay texture. All pedons contain allophane, mostly as Al-rich allophane with Al:Si ratio ≅ 2.0. Mineralogical analysis data demonstrate the differences in parent materials, including quartz, plagioclase feldspar, hypersthene, augite, hornblende and magnetite. Halloysite and kaolinite are also present in the soils. When allophane is the dominant material in the clay fraction, the chemical properties are characterised by accumulation of humus, high fluoride pH and high phosphate retention. State factors of soil formation are reviewed and discussed. This study reveals that weathering processes are key determinants of site-specific environmental conditions, whereas compositional factors, including tephra age, may determine A1 behaviour, and control the concentration of A1 in soil solution and its distribution throughout the profile. Four soils meet the andic criteria and qualify for the Andisols order. They are: Typic Udivitrand, ashy, isofrigid; Typic Hapludand, medial, isofrigid; Typic Hydrudand, hydrous, isofrigid; and Hydric Endoaquand, medial, isofrigid. Another soil is under the Entisols order and is classified as Vitrandic Udifluvent, sandy, mixed, isofrigid. The Andisols are correlated with Allophanic Soils in the New Zealand Soil Classification. The complete classification is: vitric Orthic Allophanic Soil, vitric Orthic Allophanic Soil, typic Orthic Allophanic Soil, and typic Impeded Allophanic Soil. The Vitrandic Udifluvent is correlated with typic Orthic Pumice Soil.Item Linking distal volcaniclastic sedimentation and stratigraphy with the growth and development of stratovolcanoes, Ruapehu volcano, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of PhD in Earth Sciences at Massey University, New Zealand(Massey University, 2015) Tost, ManuelaLarge, long-lived stratovolcanoes are inherently unstable, and commonly experience large -scale flank collapse. The resulting debris avalanches permanently alter the edifice and the valleys they impact. New mapping reveals that at least six hitherto unknown debris avalanches occurred from Mt. Ruapehu, New Zealand. They collectively inundated >1,200 km2 and ranged between 1.3 and >3 km3 in volume, the latter being the largest debris avalanche known from the volcano. Constriction of the sliding debris avalanches into deep river valleys enhanced basal erosion, incorporation of water-saturated substrate and formation of a basal lubrication zone. This led to runouts of up to 100 km, 2 - 3 times longer than expected for equivalent unconfined dry landslides. Two of the seven river catchments affected by debris avalanches were truncated from the volcano by proximal debris choking. The debris avalanches commonly coincided with warming from glacial into interglacial periods and rapid deglaciation of Mt. Ruapehu. A loss of ice-armouring of the slopes and increased water saturation likely weakened the edifice. At least two of the debris avalanches were triggered by intrusion of new magma into the mountain. The highly resistant debris-avalanche deposits form distinctive plateaus at the highest topographic elevations along present eroding river valleys, in places reflecting earlier drainage pathways. Deposit ages and those from lower climate-controlled (non-volcanic) fluvial aggradational terraces allowed calculation of regional uplift rates, which varied between 1.3 ± 0.5 mm yr-1 to 5 ± 1.3 mm yr-1 over the last c. 125 ka. Each major flank failure led to decompression of the Mt. Ruapehu magmatic system, triggering pulses of numerous large -scale eruptions and syn-eruptive lahars. Ar- Ar dating of lava clasts within the debris avalanche deposits provided evidence of volcanic episodes that are not exposed on the present edifice. The oldest deposits from Mt. Ruapehu are now identified at =340,000 ka and show that a complex multi -stage storage magma system was operating, similar to that of the present day. Hornblende -bearing xenoliths from these lavas show that a magmatic crustal underplate at >40 km depth existed beneath the volcano by ~486.5 ± 37.6 ka. Combined, samples from the mass -flow deposits and the cone lavas show more complex variation over time than previously thought, but generally reflect a progressively increasing heat flux and a shift of the magma -storage system from the lower crust to mid- and upper -crustal levels.Item Late quaternary volcanic stratigraphy of the southeastern sector of the Mount Ruapehu ring plain New Zealand : a thesis presented as partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science(Massey University, 1991) Donoghue, Susan LeighMt Ruapehu is an active composite strato-volcano situated within the Tongariro Volcanic Centre, North Island, New Zealand. It is surrounded by an extensive ring plain built principally from laharic deposits, capped by late Pleistocene and Holocene-aged tephras. Stratigraphic studies and geologic mapping on the southeastern sector of the Mt Ruapehu ring plain have identified six andesitic tephra formations (Tufa Trig Formation, Ngauruhoe Formation, Mangatawai Tephra, Mangamate Tephra, Pahoka Tephra, Bullot Formation) erupted from Mt Ruapehu, Mt Tongariro and Mt Ngauruhoe during the past c. 22 500 years. A seventh formation, Papakai Formation, comprises both andesitic tephra and tephric loess. Most of the tephras erupted from Mt Ruapehu are grouped into the Bullot and Tufa Trig formations which are of late Pleistocene to Holocene age. Other intermittent eruptions during the Holocene have contributed tephra to the Papakai Formation. The Bullot Formation tephras represent a period of active and widespread tephra deposition from subplinian eruptions. Most of the tephras have been deposited to the east of the volcano under the influence of prevailing westerly winds, with an average eruption interval of approximately one event every 200 years. Tephras of Tufa Trig Formation are the products of small hydrovolcanic eruptions and, although erupted more frequently (one event approximately every 100 years), have contributed comparatively little tephra to the ring plain. Tephras erupted from Mt Tongariro (Mangamate Tephra, Pahoka Tephra) comprise most of the Holocene tephra record on the Mt Ruapehu ring plain, being deposited during a period of quiescence at Mt Ruapehu. Their eruption is coincident with the introduction of mixed magmas beneath Mt Tongariro. Fourteen rhyolitic tephra formations (Kaharoa Tephra, Mapara Tephra, Taupo Pumice, Waimihia Tephra, Hinemaiaia Tephra, Whakatane Tephra, Motutere Tephra, Poronui Tephra, Karapiti Tephra, Waiohau Tephra, ?Rotorua Tephra, Rerewhakaaitu Tephra, Okareka Tephra, Kawakawa Tephra Formation) erupted from the Okataina and Taupo volcanic centres of the central North Island have also been identified. They are important marker beds used to date andesitic tephras and laharic deposits preserved on the southeastern ring plain. The stratigraphic relationships between these distal rhyolitic tephras, and their relationship to local andesitic tephras is discussed, and the stratigraphy of some rhyolitic tephras identified by Topping and Kohn (1973) revised. The tephras have been identified from their stratigraphic positions, ferromagnesian mineral assemblages and glass shard chemistries. The mineralogy and chemistry of selected andesitic marker beds has been detailed for purposes of regional identification and correlation. A database for Tongariro Centre tephras is established using ferromagnesian mineral assemblages and major element chemistry of ferromagnesian phenocrysts, and glass determined by electron microprobe analysis. The potential for use of andesitic tephra mineralogy in stratigraphic studies is evaluated. The ferromagnesian mineral assemblage of Tongariro Volcanic Centre tephras comprises orthopyroxene + clinopyroxene ± olivine ± hornblende. Orthopyroxene compositions project mostly as hypersthene, and clinopyroxenes as augite. Olivine and hornblende are valuable marker minerals to the identification of some tephras. The olivines are forsteritic, some of which show distinctive skeletal morphology. The hornblende phenocrysts are calcic amphiboles and project mostly as pargasitic hornblende. Groundmass glass compositions of some pumice lapilli range between andesite and rhyolite. Bulk rock compositions are andesite. The deposits of debris flows and hyperconcentrated flood flows comprise much of the prehistoric stratigraphy of the southeastern Ruapehu ring plain, with minor fluvial lithologies, indicating lahars are common events at Mt Ruapehu. The deposits are grouped into five formations (Onetapu Formation, Manutahi Formation, Mangaio Formation, Tangatu Formation, Te Heuheu Formation) on the basis of lithology. The stratigraphic relationships between these formations is discussed and their distributions mapped. These formations form the major constructional surfaces of the southeastern ring plain. They are envisaged as having been generated following large scale sector collapses of the southeastern flanks of Mt Ruapehu, and by snow and ice melt associated with eruption of hot pyroclastic ejecta, the ejection of Crater Lake waters, or by heavy rains inducing widespread flood events, capable of eroding flank and ring plain materials. Much of the erosion and aggradation that has occurred within the Rangipo Desert in the last c. 1800 years is attributable to lahars. At least 35 laharic events are recorded on the southeastern ring plain within the last c. 22 500 years. The most active period of lahar generation is the present day, with an average incidence of one event every 11 years. Many of the recent lahars have been confined within Whangaehu Valley.Item Late quarternary volcanic stratigraphy within a portion of the northeastern Tongariro volcanic centre : a thesis presented as partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science(Massey University, 1996) Cronin, Shane JasonInvestigation of the Late Quaternary volcanic stratigraphy within the andesitic Tongariro Volcanic Centre has elucidated the history of construction of the northeastern Ruapehu and eastern Tongariro ring plains and provided a lahar record for the Tongariro catchment. Volcaniclastic ring-plain sequences were correlated and dated using rhyolitic and andesitic marker tephras. The identification of distal rhyolitic tephras in the area was improved by the application of discriminant function analysis (DFA) to their electron microprobe-determined glass chemistry. The Okaia. Omataroa and Hauparu Tephras and the Rotoehu Ash were identified for the first time in this area, providing a chronology for pre-22.6 ka ring-plain sequences not previously investigated. DFA of ferromagnesian mineral chemistry proved useful for discrimination of andesitic tephras. with titanomagnetite being the most useful phase. Development of an andesitic tephrostratigraphy in pre-22.6 ka sequences was aided by clustering analysis and DFA. Seven andesitic marker tephras were identified using a range of parameters to supplement the rhyolitic tephrostratigraphy. Using the tephrochronologic framework, 15 packages of lahar deposits were identified on the northeastern Ruapehu ring plain (from >64 to c. 5.2 ka) and six on the eastern Tongariro ring plain (from >22.6 to 11.9 ka). Lahar deposition on both ring plains was most voluminous and widespread during the last (Ohakean) and antepenultimate (Porewan) stadials of the last glacial (Otiran). Holocene lahars were restricted to a narrow sector of the northeastern Ruapehu ring plain. They appear to have been triggered mostly in response to large-scale tephra eruptions of Ruapehu and Tongariro, and mostly occurred along the path of the Mangatoetoenui Stream. Lahar deposits and surfaces beside the Tongariro River were mapped in eight lahar hazard zones, with lahar recurrence intervals ranging from 1 in >15 000 years to 1 in 35 years. The largest number and volume of lahars in this catchment occurred in the period from 14.7 to 10 ka. The greatest population risk identified in the Tongariro catchment is part of Turangi, built within a 1 in 1000 year lahar-hazard zone. Other property and infrastructure at greater risk include the State Highway 1 bridge across the Mangatoetoenui Stream and the Rangipo Dam and Power Station, within a 1 in 35 year hazard zone. The landscape of the northeastern Ruapehu and eastern Tongariro ring plains has developed in relation to late Quaternary climate changes in addition to volcanic activity. During the last and antepenultimate stadials of the last glacial, major ring-plain aggradation by lahars and streams occurred. This was probably in response to greater physical weathering and glacier action on the volcanic cones providing abundant sediment for lahars. During the warmer interstadials of the last glacial, soil development within andesitic ring plain material was greatest, particularly when the rate of soil accretion was low.Item Andesitic Plinian eruptions at Mt. Ruapehu (New Zealand) : from lithofacies to eruption dynamics : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, (Palmerston North, Manawatu), New Zealand(Massey University, 2012) Pardo Villaveces, NataliaA new detailed stratigraphy was developed for a sequence of pyroclastic deposits including the largest known eruptions associated with Mt. Ruapehu, deposited in the period ~27-10 ka BP cal. From the largest Plinian eruption deposits in this sequence, subtle lithofacies variations within componentry, pumice textures and sedimentary features were used to identify a systematic change in eruptive conditions over time. Early eruptions involved steady eruption columns, while younger eruptions involved unsteady, collapsing columns. Isopach and Isopleth (pumice and lithic) mapping of most widespread and distinctive units show that the largest explosive eruptions known from this volcano attained peak column heights between 22 and 37 km, with mass discharge rates reaching 107-108 kg/s. To characterise the conditions controlling the style of Plinian eruptions at this andesitic volcano, and to explain the systematic variation in column stability over time, five key units were sampled in detail, exemplifying the major contrasting lithofacies. The sampled tephras underwent grain-size analysis, along with quantification of componentry, porosimetry and density on particles of a range of size classes, as well as 2D and 3D microtextural analyses of juvenile pumice clasts to define vesicularity and crystallinity. In addition, physiochemical factors such as melt-evolution and volatile-contents were determined by analysing bulk pumice, glass-inclusions and residual glasses with electron microprobe and FTIRspectroscopy. Bulk compositions of these tephras vary from basaltic-andesite to andesite (56-62 wt.%, SiO2), and had minimum pre-eruptive H2O contents of 4-5 wt.%. The evolution of eruption behaviour over time was not correlated to any progressive change in bulk geochemical properties, but instead resulted from variations in physical processes within the conduit. Ascending magmas experienced heterogeneous bubble nucleation, and later-erupted units showed increasing degrees of rheological heterogeneities developed across the conduit. Differences between units were due to changes in the magma decompression rates, the degree of bubble-crystal-melt interactions and bubble shearing, as well as the composition of the residual melt. Conditions that led to the most variable physical states of the magma reaching the fragmentation level resulted in the highest variability in pumice textures, the greatest range in styles of fragmentation, and the most unstable eruption columns. A new model describing the pre-eruptive magma storage region, conduit processes, magma fragmentation, and pyroclastic dispersal during Plinian eruptions at Mt. Ruapehu is proposed. This hypothesises that eruption column unsteadiness and collapse occurs when magma shear reaches extreme levels along the conduit under conditions of low isolated porosity (<3 vol.%). This situation also generates the worst-case hazard scenarios expected for Ruapehu, eruptions, where Plinian columns of over 30 km may produce widespread tephra fall, as well as partially collapse to generate pyroclastic density currents of over 15 km runout.Item Understanding the Holocene explosive eruption record of the Tongariro Volcanic Centre, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, Palmerston North, New Zealand(Massey University, 2010) Moebis, AnjaThe Tongariro Volcanic Centre has experienced many VEI 1-4 eruptions over the last 12 000 cal. yrs. B.P., dominantly from Ruapehu, Ngauruhoe and Red Crater. The historic record of 150 years alone is insufficient to provide a robust understanding of future volcanic hazard, necessitating a quantification of eruption parameters from the geological record. The major obstacle to this is untangling a complex sequence of interdigitating, fine-grained and poorly distinguishable tephras from the three source volcanoes. With detailed mapping and using volcanic glass chemistry, tephras from the three sources were discriminated. This has led to a revision of the age of Ngauruhoe to be at least 6500 cal. yrs. B.P., around 4000 years earlier than previously thought. It also provides the most detailed explosive eruption frequency and magnitude record from the area since 12 000 cal. yrs. B.P. Ruapehu and Ngauruhoe tephras were characterised by initial phreatomagmatic explosions that transformed into dry magmatic (strombolian) phases. Magma-water interaction is shown by basal layers of pale-brownish-grey fine ash, containing blocky glass shards with small isolated spherical vesicles, and exhibiting surface conchoidal and step-like fractures. The magmatic phase ash is microlite-rich, with dark glass containing elongate vesicles with thin bubble walls and irregular surfaces. The largest eruption recognised from Ngauruhoe, produced a distinct dark purple tephra, with a well-constrained volume of 26.6 x106 m3, and a probable eruption column height of about 15 km. The total tephra volume from Ngauruhoe is estimated to be 952 x 106 m3, around 50% of the known lava volume. A climactic eruption period of Ngauruhoe occurred between ~ 2900 and 2700 cal. yrs. B.P., during which 64% of its known explosive eruptions occurred, including its largest known events. This phase, representing 3% of the volcano’s lifespan, produced 57% of its pyroclastic output. Over the last 12 000 cal. yrs. B.P., the frequency of Ruapehu eruptions appears to have increased about 2000 yrs B.P., but this may reflect better preservation and exposure of the more recent tephras. Bursts in Ruapehu explosive activity have occurred out of phase with those from Ngauruhoe. The minor pyroclastic cone of Red Crater represents an eruption site that was active for at least ~ 4000 cal. yrs. B.P. and has mainly been characterised by effusive events. Since around 900 cal. yrs. B.P. minor explosive events have occurred from this location, increasing in magnitude from 400 cal. yrs. B.P.Item The clockwork lahar : examining issues management in a New Zealand public service context : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Management in Communication Management at Massey University, Palmerston North, New Zealand(Massey University, 2008) Dittmer, David MarkIssues management has been practised over the past 30 years. However, the literature has focused on how corporations manage issues, while public service organisations have been ignored. This study looked at the issues management of a tephra dam-break lahar from 1996-2007 on Mount Ruapehu, New Zealand by a group of public service organisations. 19 interviews were conducted with people involved with the management of the ‘lahar issue’ to find out how the issue was managed. Further a content analysis of 309 articles from five newspapers, spanning the full eleven year period, was conducted to examine the salience (attention) given to the issue, the frames commonly used to present the issue and the sources who ‘drove’ the issue. The data from the content analysis was interpreted to create a five-stage lifecycle of the ‘lahar issue’. Further, data from the interviews was compared with a summary process of the issue management process. This comparison showed that five issues management process stages were employed to manage the ‘lahar issue’ although they were not referred to as such. Initially, the Department of Conservation consulted stakeholders during the development of options to deal with the lahar (1996-1999). Later in the lahar’s management, lahar stakeholders fell into two categories: internal - those involved with the mitigation and response - and external - the public. Internal stakeholders were communicated with through meetings and email. External stakeholders were communicated with through local media, presentations and meetings. Overall, it was concluded that media gave substantial attention to the lahar issue over the eleven year period. Some of those involved with managing the ‘lahar issue’ were able to identify the phases of media coverage. Further, this study identified ten frames that media employed when reporting the lahar. The most-frequently used frames were those focusing on the response (lahar response), describing the lahar (diagnosing causes of problem(s)) and discussing the potential impacts from a lahar (definition of problem(s)). Department of Conservation Scientist, Dr Harry Keys, was shown to be a primary definer – an influential source. The results suggest he defined coverage because of his status as both an official source, due to the organisation he was associated with, and also as an authoritative source due to his role as a scientist. Further, he was regularly drawn upon as a source over the entire period of the ‘lahar issue’ coverage.Item Robbanásos kitörés az éj leplealatt (A tudomány új eredményei - első kézből).(Massey University., 2007-01-01) Nemeth, KarolyNo abstract available