Seismicity From Modern Magmatic Activity Beneath Taupō Volcano, Aotearoa New Zealand

AbstractTaupō is an active caldera volcano lying beneath Lake Taupō in the central North Island, Aotearoa New Zealand. It last erupted 1,800 years ago, and today has background seismicity interspersed with unrest episodes, most recently in 2019 and 2022–2023. It presents challenges in monitoring due to the lake and consequent limited control on volcano‐related earthquake locations. Using national seismometer network data and 13 temporary broadband seismometers, we detected and located earthquakes near Taupō between October 2019 and September 2022. We refined the locations with relative relocation, and calculated magnitudes along with selected focal mechanisms. Seismicity beneath the northern part of the lake was related to the volcano's magmatic system: seismicity rates increased during the unrest and varied focal mechanisms demonstrate a lack of tectonic control. An arcuate shape in the seismicity at 6 km depth resulted from the interaction of the magmatic system with a caldera ring fault. The arcuate shape was visible in the background seismicity before the start of the 2022–2023 unrest episode but was particularly active during the first months of unrest, reflecting intrusive episodes into the rhyolitic magma reservoir. In contrast, earthquakes north of the lake, as well as around and beneath the southern part of the lake, demonstrated tectonic controls, with rift‐aligned focal mechanisms and seismic swarms. Improvements that could be made to routine earthquake characterization at Taupō and allow detailed interpretation of activity in near‐real‐time include: a volcano‐specific velocity model, a lower threshold to identify earthquakes, routine relative relocation, and enhanced seismic instrumentation.