There are currently 74 productive geothermal systems associated with volcanic centers (VCs) in subduction arcs globally, including actively producing systems, past producing systems, and systems with successful flow tests. The total installed or tested capacity of these 74 geothermal systems is 7,605 MWe, ranging from 0.7 MWe each at Copahue, Chile and Barkhatnaya Sopka, Kamchatka) to 795 MWe, Larderello, Italy, and averaging 90.5 MWe per system. These 74 productive VCs constitute 10% of 732 VCs distributed across more than a dozen major subduction VCs around the world. The intra-arc (within-arc) tectonic setting is highly variable globally, ranging from extension to transtension, transpression, or compression. Furthermore, the shear strain associated with oblique plate convergence can be accommodated by either intra-arc or arc-marginal deformation. The structural-tectonic settings of these 74 productive VCs were characterized to add to a global catalog of parameters to help guide future exploration, development, and regional resource potential. Five summary parameters were characterized; tectonic setting (e.g., extensional or compressional), angle of plate convergence relative to the arc axis, distribution of Quaternary fault activity (e.g. scarps), fault slip rates, and local structural setting. Each of these parameters have associations with the electrical productivity of volcanic centers (MWe/VC) and capture different aspects of the structural-tectonic influence on the geothermal potential of each VC. The regional tectonic setting of the 74 VCs include 11 (15%) extensional, 43 (59%) transtensional, 4 (5%) transpressional, 7 (9%) compressional, and 9 (12%) unknown environments. Importantly, 73% of the VCs are in extensional or transtensional environments and these are responsible for 88% of the total known MWe capability in global subduction arc settings. At a local scale the VCs are associated with a number of structural settings, including 10 (14%) in pull-aparts along strike-slip fault zones, 15 (20%) in association with displacement transfer zones where strike-slip faults merge with normal faults, 4 (5%) in normal fault accommodation zones, 7 (9%) in normal-fault step-overs, 22 (30%) associated with fault intersections, 4 (5%) in other settings, and 12 (16%) in unknown settings. Of these structural settings, the pull-aparts, displacement transfer zones, step-overs, and accommodation zones accounted for 49% of the productive VCs and 76% of the total MWe. In contrast, the fault intersections included 30% of the VCs but only 16% of the total MWe. Quaternary fault densities and fault slip rates also show positive relationships with MWe capability. One of the primary conclusions is that productive geothermal systems associated with subduction arc VCs are mining convective heat flow co-located with areas of active, extensional, intra-arc strain.

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