Abstract Combined interpretation of Electrical Resistivity Tomography (ERT) data, with plume and fumarolic gas emissions provides a snapshot of the Whakaari/White Island hydrothermal system 11 months prior to an eruption on December 9, 2019. Two and three dimensional inversion of the ERT data images the F0 fumarole as a low resistivity (2–5 Ωm) feature reflecting the two-phase zone surrounding the single phase vapour conduit. Crucially, interpretation of the inversion images is well constrained by a large existing dataset of rock electrical properties, including surface conductivity, porosity and intrinsic formation factor, alongside new measurements of liquid phase electrical conductivity taken from a range of hot-springs on the island. Pore-filling liquids are an order of magnitude more conductive than sea-water with their low to very low pH (3.4 to −0.3) contributing to their extremely conductive nature. An extensive low-resistivity feature (0.2 Ωm) at ~125 m depth is therefore interpreted as a liquid saturated layer exposed to hydrothermal alteration by acid fluids. The intersection of the F0 fumarole trace with this layer is coincident with a previously determined source of deformation, suggesting that heat transport inside the fumarole conduit pressurises surrounding liquid and vapour filled pore space, generating the deformation signal. The timeseries of fumarolic and plume emissions in the year prior to the ERT survey show that the gases transported by the fumarole are a mixture of high temperature magmatic vapour and lower temperature gas equilibrated within the hydrothermal environment. Interpretation of the gas data suggests that the snapshot captured by the ERT image shows the single-phase vapour and two-phase vapour-liquid regions adjacent to the conduit were likely at close to their smallest extent, consisting of mostly hydrothermal derived gases.

中文翻译：

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来自新西兰 Whakaari/White Island 的电阻率层析成像和延胡索组成的岩浆/热液系统快照

摘要 电阻率断层扫描 (ERT) 数据与羽流和喷气式气体排放的组合解释提供了 2019 年 12 月 9 日喷发前 11 个月的 Whakaari/怀特岛热液系统快照。 ERT 数据的二维和三维反演将 F0 喷气孔成像为低电阻率 (2–5 Ωm) 特征，反映了单相蒸汽导管周围的两相区域。至关重要的是，反演图像的解释受到大量现有岩石电学特性数据集的限制，包括表面电导率、孔隙度和固有地层因子，以及从岛上一系列温泉中获取的液相电导率的新测量值。孔隙填充液的导电性比海水高一个数量级，因为它们的 pH 值从低到极低 (3. 4 到 -0.3) 有助于它们的极导电性。因此，在约 125 m 深度处的广泛低电阻率特征 (0.2 Ωm) 被解释为暴露于酸性流体热液蚀变的液体饱和层。F0 喷气孔轨迹与该层的交叉点与先前确定的变形源一致，表明喷气孔导管内的热传递对周围充满液体和蒸汽的孔隙空间加压，从而产生变形信号。ERT调查前一年的喷气孔和烟柱排放时间序列表明，喷气孔输送的气体是高温岩浆蒸气和在热液环境中平衡的低温气体的混合物。