Taupō volcano’s restless nature revealed by 42 years of deformation surveys, 1979–2021

ABSTRACT

Lake Taupō, New Zealand, conceals a large caldera volcano which last erupted in 232 AD. A surveying experiment in 1979 which utilised the surface of the lake for detecting small movements of the lakebed soon became a programme to monitor vertical deformation by making regular observations at 22 fixed points – survey stations – around the lake. The programme continues today with 4 surveys being made annually. In this paper, we review the methodology and present the 42 year-long dataset in graphical forms, and draw conclusions on its implications in terms of volcanic and tectonic deformation. We also make the dataset available for download. The dataset confirms that vertical deformation is occurring in the lakebed. Long periods of slow deformation, dominated by subsidence totalling 140 mm in the Taupō Fault Belt at the northern end of the lake, and to a lesser degree at the southern end, are interrupted by uplift episodes now reaching 160 mm in the northeastern sector containing the most recent active vents. We suggest that the subsidence is primarily tectonic while inflation episodes are driven by upward migration of magma to shallow levels during periods of unrest.

KEYWORDS:

• Taupō
• Taupō Volcanic Zone
• volcano geodesy
• volcano monitoring
• volcanology

Acknowledgements

The lead-author is indebted to all his colleagues in the Department of Scientific and Industrial Research (DSIR) who encouraged and assisted him to set up and the lake levelling project in 1979, providing both physical assistance and scientific advice over the following 23 years, particularly George Grindley, John Latter, Graeme Blick, Peter R. Wood, Ian Nairn and Colin J.N. Wilson. He is also grateful for the early advice from George Walker to particularly monitor the Horomatangi Reef, and to Don Swanson of the US Geological Survey for continuing the monitoring programme during the lead-author’s absence in 1984. The dedicated and professional work by Steve Currie and his team at ESL, overseen by Brad Scott of GNS Science, must also be highly commended for ensuring the smooth operation of the programme since 2002 and its integration with GeoNet. Authors FIK and ERHM are supported by the ECLIPSE programme, which is funded by the New Zealand Ministry of Business, Innovation and Employment (MBIE). FIK is also supported by New Zealand Earthquake Commission Programme in Earthquake Seismology and Tectonic Geodesy at Victoria University of Wellington. Figures in this manuscript were generated using GMT (Wessel et al. 2019).

Disclosure statement

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

Data availability statement

The full lake-levelling dataset that supports the findings of this study is openly available in spreadsheet and csv format in zenodo at https://doi.org/10.5281/zenodo.5777476.

Additional information

Funding

This work was supported by Earthquake Commission [grant number 3185]; Ministry of Business, Innovation and Employment [grant number ECLIPSE/3487].