Characterizing the subsurface structure and stress of New Zealand's geothermal fields using borehole images

Borehole imaging captures geological information on lithology, structure, and stress in the Earth's subsurface. This paper synthesises currently analysed borehole imaging data acquired in geothermal fields in the Taupo Volcanic Zone. Structure and stress orientations agree with the tectonic trend, though display variation between and within geothermal fields. Structural variability is related to larger scale rift fault architecture, while stress orientation variations are related to active structures. Borehole images also provide information on structural fluid flow pathways in TVZ geothermal fields showing structures with NE-SW and E-W strike orientations and wide fractures occur within fluid flow zones.