Thermal remanence of the ∼0.6 kya Rangitoto volcano eruption, Auckland volcanic field (New Zealand) inferred from self-potential and CO₂ flux measurements
Abstract
Rangitoto volcano is the most recent (⁓0.6 ka) and voluminous volcano in New Zealand's Auckland Volcanic Field (AVF). In this study, we investigate the status of its hydrothermal system using a combination of self-potential (SP) and CO2 gas flux measurements along the west-east Rangitoto-Motutapu main road. SP data revealed a "W"-shaped signal near the main crater, indicating an active hydrothermal system. In contrast, the CO2 flux data showed diffuse emissions peaking ⁓620 m east of the SP anomaly peak, suggesting they originated from different sources. The SP anomaly is likely due to a hydrothermal system heated by a shallow, cooling basalt body, and CO2 emission is from deeper crustal or mantle sources. An SP electric potential offset was also detected at the Islington Bay Fault under the Rangitoto-Motutapu bridge without a corresponding CO2 flux anomaly.
Plain language summary
By measuring subtle electrical and gas signals along the road across Rangitoto Island (Auckland's youngest volcano), researchers detected signs of an active underground hydrothermal system near the main crater, likely heated by cooling volcanic rock, plus a separate zone of gas seepage further away. This is evidence that even a "dormant" 600-year-old volcano still has ongoing underground activity.
Citation
Luthfian A, Finizola A, Mazot A, Adam L, Gusset R, Eccles J. (2025). Thermal remanence of the ∼0.6 kya Rangitoto volcano eruption, Auckland volcanic field (New Zealand) inferred from self-potential and CO₂ flux measurements. Volcanica.
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Authors
Luthfian A, Finizola A, Mazot A, Adam L, Gusset R, Eccles J.
Published in
Volcanica
Peer reviewed
Yes
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