- Volcanic structures in the form of stratovolcanoes are obvious locations of interest, but it depends on how recent they were formed and whether active. Holocene volcanoes (<10,000 years old) are likely more favourable for active heat resources. Active volcanoes can be currently erupting or could have the potential to erupt (dormant). Volcanic seismicity is a good indication of whether magmatic activity is going on down below. Other good indications are ground deformation and thermal surface manifestations.
- Volcanic materials could have been ejected, expelled and emplaced over many eruptive cycles resulting in- complex volcanic stratigraphy with a build up of layers. Some layers may have formed beneath the seawater surface as the volcanic structure grew, so some of the resultant rapidly cooled lava flows would have produced well jointed brecciated flows. The thickness of deposit layers could vary significantly. Volcanic ash flow deposits could also be significant characterised by extreme variability mixed with volcanic debris.
- The complex nature of these elements means that the geology will be extremely heterogenous which would complicate investigating the potential fluid and heat flow pathways, potential deposit layers with enough effective permeability to be potential reservoirs, and potential altered zones (clay caps with smectite and/or mixed clay layer minerals) on top of such reservoirs.
- Some view and understanding of deep subsurface magmatic conduits is necessary to help identify potential conductive and convective heat pathways to where this heat can be economically accessed. Deep heat resources will be available, but shallow heat resources in hydrothermal reservoirs would be able to be more quickly investigated, evaluated, and drilled to determine if suitable for potential development.
