The USGS has it rated as very high.
Yellowstone is rated high.
https://www.usgs.gov/volcanoes/long-valley-caldera/
From the article you posted...
“A robust geothermal system inside the caldera fuels the Casa Diablo power plant, which generates enough power for 40,000 homes.”
I don’t Spanish, but doesn’t CASA DIABLO translate to the “house of Satan”?