Integrating records of explosive and effusive activity from proximal and distal sequences: Mt. Taranaki, New Zealand
2011
Turner, Michael B. | Cronin, Shane J. | Bebbington, Mark S. | Smith, Ian E.M. | Stewart, Robert B.
A complete record of eruption activity is required for a robust volcanic hazard assessment, characterising the types and magnitude of possible activity and the relative frequency of these different types of eruptions. This paper documents a record of Holocene volcanic eruptions from Mt. Taranaki, New Zealand, with the aim of integrating the records of explosive and effusive style eruptions from this volcano. Discriminant function analysis of titanomagnetites from Mt. Taranaki is used to correlate a set of well-dated tephras from lake cores with comparatively poorly dated eruption units that outcrop on the flanks of the cone. Using this process the stratigraphic sections reveal that much of the current edifice was constructed between 6000 and 5000Cal.BP by prolific lava effusion events. The period of intensive effusive activity followed edifice modification by a major flank-collapse and debris avalanche. This demonstrates that trends in the frequency of effusive activity may vary independently of explosive eruption patterns. Examining the range of processes controlling the occurrence of a range of eruption types and the distribution of their products is essential for the production of robust probabilistic-based eruption forecasting models. In addition, the geochemical data on the widely dispersed Taranaki tephras presented here, tied to this new high-resolution eruption chronology, can be used to constrain future studies of landscape and climatic evolution across large areas of the North Island of New Zealand.
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