Caldera volcanoes produce Earth’s largest explosive eruptions, generate seismicity both independent and associated with unrest and eruptive periods, host mineral and geothermal resources that interact with groundwater, and support a largely unexplored biosphere. Many silicic calderas are hosted in an active rift. Volcanic, tectonic, hydrologic and biosphere processes in calderas are intimately connected, yet poorly understood, and require subsurface observations.

We hypothesise that the history of interplay between tectonic and magmatic processes across caldera/rift intersections explains differences in hydro-bio-processes inside, outside, and at the margins of calderas. We also propose that precursors to caldera unrest can be detected early in drillholes by changes in crustal strain; fluid properties; and, in what would be a world first, exploring the possibility of using microorganisms as subsurface biosensors.

Keywords: Oceania, New Zealand, Biosphere, Caldera, Hydrology, Magnetism, Tectonics