WELLINGTON, New Zealand (AP) — When researchers in New Zealand drilled deep into an earthquake fault, they stumbled upon a discovery they say could provide a significant new energy source for the South Pacific nation.

The scientists found the water in the Alpine Fault was much hotter than expected, and could potentially be harnessed to generate electricity or provide direct heating in industries like dairy farming.

The finding was surprising because geothermal energy is usually associated with volcanic activity, but there are no volcanoes where the scientists drilled. Because the Alpine Fault...