Authors
Szabolcs Kósik
Publication date
2018
Institution
Unpublished PhD Thesis, Massey University, Palmerston North, New Zealand
Description
In the past 350 ky, the Taupo Volcanic Zone (TVZ) has been the most productive silicic volcanic region in the world, with 12 silicic large-volume (35-2200 km3 DRE) calderaforming eruptions and hundreds of predominantly silicic smaller-volume eruptions. These spatially and temporally scattered small-volume events are characterised by relatively short-lasting single eruptive episodes that may have been strongly influenced by location-specific environmental factors. The aim of this study is to evaluate the volcanic hazards associated with the activity of these small-volume volcanoes using two different approaches. At the local scale, possible eruption scenarios were defined through three example localities (Ohakune, Motuoapa, Puketerata) that are characterised by different chemical compositions, eruption styles, as well as distinct environmental conditions representative of the entire TVZ. At the field scale, evaluation of small-volume activity was focused on the spatio-temporal and volumetric distribution of vents and their relationship to the structural elements of the TVZ. The most common small-volume eruptions form lava domes that were originally thought to be rarely associated with explosive activity. In contrast, this study shows that dome emplacement is often accompanied by explosive activity. However, the associated pyroclastic deposits are characterised by a low preservation potential. The most likely scenario for future eruptions is a rhyolitic eruption with an initial phreatomagmatic phase followed by the effusive emplacement of lava with or without associated explosive activity. Based on the average eruptive volumes (0.2-0.3 km3) of single …
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