AFAIU the "last mile" (or last 5--17 km) transfer largely occurs through ground-water migration. Yellowstone combines extensive geothermal energy with ample su

AFAIU the "last mile" (or last 5--17 km) transfer largely occurs through ground-water migration. Yellowstone combines extensive geothermal energy with ample surface water flow (e.g., Lake Yellowstone, which is itself a major geothermal zone). I'm really well beyond my depth here, though looking up soem background: Geological diagram of Old Faithful: <https://public-media.smithsonianmag.com/filer/bd/06/bd0603df-a976-44b2-9300-5936c3b5eb52/ofdiagram.jpg https://public-media.smithsonianmag.com/filer/bd/06/bd0603df...> From this Smithsonian article: <https://www.smithsonianmag.com/smart-news/seeing-beneath-old-faithful-180965230/ https://www.smithsonianmag.com/smart-news/seeing-beneath-old...> "Old Faithful's Geological Heart Revealed": <https://www.sciencedaily.com/releases/2017/10/171005190243.htm https://www.sciencedaily.com/releases/2017/10/171005190243.h...> Mostly addresses seismic activity, though there's some discussion of inferred structures from that. Based on the journal article by Sin-Mei Wu, Kevin M. Ward, Jamie Farrell, Fan-Chi Lin, Marianne Karplus, Robert B. Smith. "Anatomy of Old Faithful from subsurface seismic imaging of the Yellowstone Upper Geyser Basin". Geophysical Research Letters, 2017; DOI: 10.1002/2017GL075255 <http://dx.doi.org/10.1002/2017GL075255 http://dx.doi.org/10.1002/2017GL075255> (The Smithsonian piece is based on the same article.)