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GeoNet observations during the 2022-23 unrest episode at Taupō caldera volcano, Aotearoa New Zealand

Oliver Lamb1 , Sigrún Hreinsdóttir2, William Power2, Stephen Bannister2, John Ristau2, Craig Miller1, Eleanor Mestel3, Finnigan Illsley-Kemp3, Katie Jacobs2, Steve Sherburn1, Jonathan Hanson2, Elisabetta D'Anastasio2, Eveanjelene Snee2, Mike Ross2, Ian Hamling2, Aleksandr Spesivtsev2, Jean Roger2, Aditya Gusman2, Xiaoming Wang2, David Burbidge2, Michael Rosenberg1, Jackson Shanks1, Cameron Asher1, Karen Britten1, Richard Johnson1

  • Affiliations: 1Te Pū Ao | GNS Science, Wairakei Research Centre, Taupō, 3384, New Zealand; 2Te Pū Ao | GNS Science, Avalon Campus, Lower Hutt, 5010, New Zealand; 3Te Kura Tātai Aro Whenua School of Geography, Environment and Earth Sciences, Te Herenga Waka Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 50

  • Programme No: 3.11.10

  • Theme 3 > Session 11

Abstract

Lake Taupō in the North Island of Aotearoa New Zealand hosts a large caldera volcano that most recently erupted ~1800 years ago. The volcano has experienced ~16 unrest episodes since 1872. In May 2022 the volcano entered a new episode with increased earthquake activity and ground deformation. This episode was notable for two reasons: (1) the Volcanic Alert Level for Taupō was raised to 1 for the first time, and (2) a M5.7 on 30th November 2022 was accompanied by a small tsunami in the lake. Here we give an overview of seismic, geodetic, and tsunami observations during the unrest and what was inferred to have occurred during the unrest. Over 1780 earthquakes were detected beneath the lake over 13 months, the highest number recorded during instrumented unrest episodes at the volcano. Four distinct activity phases were identified, with earthquake relocations showing that the activity was focussed on overlapping caldera structures beneath the lake. A rapid 50 mm/yr inflation was detected within the lake, peaking during the M5.7 earthquake with 18 cm uplift and 25 cm horizontal movement recorded. GNSS data modelling suggested the inflation source was located at 4-8 km depth beneath the lake. Analysis of relative water-level gauge and survey data indicated the lake tsunami was generated by two sources: a sub-lacustrine landslide near the town of Taupō, and the rapid upward movement of the lakebed. Altogether, we suggest the 2022-23 Taupō unrest episode was caused by a new intrusion of magma at depth.