Originally published as: Mroczek, S., Savage, M. K., Hopp, C., Sewell, S. M. (2020): Anisotropy as an indicator for reservoir changes: example from the Rotokawa and Ngatamariki geothermal fields, New Zealand. - Geophysical Journal International, 220, 1, 1-17. DOI: https://doi.org/10.1093/gji/ggz400 This article has been accepted for publication in Geophysical Journal International ©:2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.