Taupōinflate: illustrating detection limits of magmatic inflation below Lake Taupō

ABSTRACT

Lake Taupō (Taupō-nui-a-Tia) infills the composite caldera above an active rhyolitic magmatic system in the central Taupō Volcanic Zone (TVZ). Ground deformation is a key unrest indicator at Taupō volcano. We present a spreadsheet tool, TaupōInflate, to calculate and plot ground deformation from magmatic inflation at depth beneath Taupō caldera. Examples show detection limits for inflating magma bodies and their ascent through the crust beneath Lake Taupō. Source locations where it is challenging to detect even substantial volumes of inflating magma bodies are as large as 20 km³, with volume changes up to 0.01 km³, 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 Ngāti Tūwharetoa through the Tūwharetoa Māori Trust Board who oversee the health and wellbeing of Lake Taupō.

KEYWORDS:

• Magma
• inflation
• Taupō volcano
• caldera
• Lake Taupō
• model
• volcano geodesy

Acknowledgements

We acknowledge useful discussions and feedback from Warwick Kissling, Grant Caldwell, and Cecile Massiot, and helpful reviews from Craig Miller and an anonymous reviewer.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials. The two supplementary figures that support the findings of this study are openly available in Figshare at https://doi.org/10.6084/m9.figshare.19618224. The spreadsheet calculator TaupōInflate and accompanying documentation are openly available at https://doi.org/10.21420/8B35-TK45.

Additional information

Funding

This research was supported by the ECLIPSE project [contract RTVU1704] funded by the Ministry of Business, Innovation and Employment.