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.