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Calculating our size- a new volume estimate for the AVF

A highly specialised systematic volume estimation model has been developed for use in New Zealand’s Auckland Volcanic Field (AVF).

In the calculations, a basaltic monogenetic volcano has been categorised into six parts.

The volume of subsurface portions – such as “pipes” (diatremes) beneath phreatomagmatic (explosion crater style) volcanoes – have been inferred using geometrical considerations, based on exposed analogue volcanoes.

Positive volcanic landforms – such as scoria/spatter cones, tephra rings and lava flows – have been defined via a Light Detection and Ranging (LiDAR) survey-based Digital Surface Model (DSM).

The volumes of outer (distal) tephra – associated with explosive eruptions – have been determined using published relationships that relate the original crater size to eruption volumes.

Utilising only the highly reliable volume estimates, the overall magma output – converted to a dense rock equivalent – for the AVF is a minimum of 1.704 km3, with lava flows making up the biggest component.

Attachments

A model for calculating eruptive volumes for monogenetic volcanoes — Implication for the Quaternary Auckland Volcanic Field, New Zealand. Cover
A model for calculating eruptive volumes for monogenetic volcanoes — Implication for the Quaternary Auckland Volcanic Field, New Zealand.

Journal of Volcanology and Geothermal Research