Taupoinflate: illustrating detection limits of magmatic inflation below Lake Taupo

Lake Taupo (Taupo-nui-a-Tia) infills the composite caldera above an active rhyolitic magmatic system in the central Taupo Volcanic Zone (TVZ). Ground deformation is a key unrest indicator at Taupo volcano. We present a spreadsheet tool, TaupoInflate, to calculate and plot ground deformation from magmatic inflation at depth beneath Taupo caldera. Examples show detection limits for inflating magma bodies and their ascent through the crust beneath Lake Taupo. Source locations where it is challenging to detect even substantial volumes of inflating magma bodies are as large as 20 km(3), with volume changes up to 0.01 km(3), owing to the restricted station placement around the lake, although a dike propagating from shallow crustal depths towards the surface is likely to be detectable. For a magma overpressure of 10 MPa, the sizes of detectable inflating bodies at depths of 5-8 km using the present monitoring system are larger than the volumes of many past eruptions, illustrating the importance of future improvements to the geodetic network. We discuss the potential for future equipment installation, including lakebed instrumentation that would require approval of local iwi Ngati Tuwharetoa through the Tuwharetoa Maori Trust Board who oversee the health and wellbeing of Lake Taupo.

Automated summary

Lake Taupo is a volcanic caldera in the central Taupo Volcanic Zone, and ground deformation is an important indicator of volcanic unrest. The authors present a spreadsheet tool, TaupoInflate, for calculating and plotting ground deformation caused by magmatic inflation beneath the caldera. Some locations around the lake have limited detection capabilities for inflating magma bodies due to station placement restrictions.