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Dating young lava flows is essential for understanding volcano's eruption frequency, yet challenging due to methodological limitations of commonly used dating techniques. Ruapehu (Aotearoa New Zealand) produced many lava flows during the Holocene, but constraints on the timing of these eruptions are scarce. Here, we use paleomagnetic dating to deliver new eruption ages of 18 lava flows with uncertainties ranging between 500 and 2,700 years (at the 95% confidence level). Comparison between lava flows' paleomagnetic directions and a local paleosecular variation record indicates that the large lava flow field located on the Whakapapa area was emplaced during at least three distinct eruptive episodes between 10600 and 7400 BP. Two of these episodes closely followed a large collapse event that affected Ruapehu's northern area and generated large volumes of lava between 10600 and 8800 BP, with the third episode producing less voluminous lava flows between 8100 and 7400 BP. Following a smaller collapse of the southeastern sector of the edifice at ca. 5300 BP, several low‐volume lava flows were emplaced during at least two distinct eruptive episodes prior to ca. 1000 BP, which supplied the Whangaehu valley with lava. The youngest age inferred from our data represents the youngest eruption age provided for a lava flow outside Ruapehu's summit region. This research provides greater detail to the Holocene effusive chronology at Ruapehu, shedding light on partial cone reconstructions after edifice collapses during the Holocene, and the time relationships between trends observed in its effusive and explosive activity. Plain Language Summary: Knowing when volcanoes have erupted is essential for hazard assessments, but the precise timing of geologically young lava flow eruptions is hard to determine with traditional methods. Earth's magnetic field is constantly changing in both direction and strength. Magnetic minerals contained in the lava flows record the direction of the field as the lava cools after eruption. Hence, solidified lavas can be dated by matching their magnetization directions to a reference record. In this study, we analyze the magnetization directions recorded in prehistoric lavas at Mt. Ruapehu (Aotearoa New Zealand) and use them to determine when they erupted. We show that a large flow field in the Whakapapa area (northwest Ruapehu) was formed during at least three distinct eruptive episodes between 10,600 and 7,350 years ago, following a catastrophic volcanic landslide at around 10,600 years ago. We also determine that the lavas present in the Whangaehu valley (east Ruapehu) erupted during at least two episodes between 4,600 and 1,000 years ago, the latter representing the youngest lavas known outside the summit area of Ruapehu. This research helps understand how Ruapehu was rebuilt after slope collapses, and the frequency of lava‐forming eruptions. Key Points: Paleomagnetism was used to date eruptive episodes in lava flow sequences at RuapehuPaleomagnetic dating yields 1300–1050 BP as the youngest eruption age known for a lava flow at the volcanoOur data provide age constraints on the timescales of vent migration and partial edifice rebuilding after collapse events [ABSTRACT FROM AUTHOR]

The Rotokawa geothermal field is in the Taupō Volcanic Zone, New Zealand. It hosts two geothermal power plants, Rotokawa and Ngā Awa Pūrua, which together have a capacity over 170 MWe. The permeability of the rock mass comprising a geothermal field controls the volume of hot fluids that can be extracted for energy production. In this research we produce a stress model to estimate in-situ rock matrix permeability for a unique set of intact rock samples obtained from depths up to 2600 m in the Rotokawa geothermal field. We show that permeability generally decreases with sample depth, both intrinsically and in response to increasing confining pressure. We explore this confining pressure effect on other petrophysical and mechanical measurements, and highlight how rock texture and composition affect how the rocks respond to confining pressure. For example, we compare two altered andesite samples: a breccia with microfractures and infilled pores that tends to experience less compaction and porosity decrease than a lava with rounded, unfilled pores. We suggest that, when developing depth-models, measurements should be conducted at relevant in-situ conditions, if possible. Finally, we explore relationships between different physical parameters and provide estimating functions for those with the clearest correlations. [ABSTRACT FROM AUTHOR]