Depositional record of historic lahars in the upper Whangaehu Valley, Mt. Ruapehu, New Zealand: implications for trigger mechanisms, flow dynamics and lahar hazards

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dc.contributor.authorGraettinger, Alison H.
dc.contributor.authorManville, Vern
dc.contributor.authorBriggs, Roger M.
dc.date.accessioned2011-01-10T03:37:18Z
dc.date.available2011-01-10T03:37:18Z
dc.date.issued2010
dc.description.abstractMt. Ruapehu, in the central North Island of New Zealand, is one of the most lahar-prone volcanoes in the world. Since historic observations began in 1861 AD, more than 50 individual lahars have been recorded in the Whangaehu valley alone, the natural outlet to the summit Crater Lake. These lahars have been triggered by a variety of mechanisms, including explosive eruptions that displaced Crater Lake water over the outlet or ejected it onto the snow-clad summit area of the volcano; rain-remobilisation of tephra deposits on steep slopes; displacement over the outlet as a result of syn-eruptive changes in lake bathymetry; and lake break-outs from Crater Lake following impoundment of excess water behind temporary barriers of tephra and/or ice emplaced over the outlet. However, only 9 lahar deposits can be distinguished in the upper Whangaehu valley on sedimentological, stratigraphic, geomorphic and petrological grounds, and these are skewed towards either the largest or the most recent flows. In some cases magnitude can be reconstructed from deposit geometry, with the largest lahars producing the highest level terraces, the coarsest deposits, and crossing drainage divides into normally inactive channels. This under-representation of historic events reflects the low preservation potential of unconsolidated deposits in a steep alpine environment, and the overprinting and recycling effect of large magnitude lahars that rework material down to bedrock and effectively reset the stratigraphic record. Development of magnitude-frequency relationships for Ruapehu lahars therefore requires the identification of lahar deposits in proximal, medial and distal settings in order to ensure that the full range of events is represented.en_NZ
dc.identifier.citationGraettinger, A.H., Manville, V. & Briggs, R.M. (2010). Depositional record of historic lahars in the upper Whangaehu Valley, Mt. Ruapehu, New Zealand: implications for trigger mechanisms, flow dynamics and lahar hazards. Bulletin of Volcanology, 72(3), 279-296.en_NZ
dc.identifier.doi10.1007/s00445-009-0318-2en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/4903
dc.language.isoen
dc.publisherSpringer Berlinen_NZ
dc.relation.isPartOfBulletin of Volcanologyen_NZ
dc.relation.urihttp://www.springerlink.com/content/e4lr153018853537/en_NZ
dc.subjectlaharsen_NZ
dc.subjectRuapehuen_NZ
dc.subjectCrater Lakeen_NZ
dc.subjectdebris flowsen_NZ
dc.subjectvolcanic hazardsen_NZ
dc.subjecttrigger mechanismen_NZ
dc.titleDepositional record of historic lahars in the upper Whangaehu Valley, Mt. Ruapehu, New Zealand: implications for trigger mechanisms, flow dynamics and lahar hazardsen_NZ
dc.typeJournal Articleen_NZ
pubs.begin-page1en_NZ
pubs.elements-id34579
pubs.end-page18en_NZ
pubs.issue3en_NZ
pubs.volumeonlineen_NZ
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