The borehole drilled almost 900 meters deep at Whataroa along the Alpine Fault on New Zealand's South Island (pictured above) revealed "extreme hydrothermal conditions," according to the journal Nature.

An international team led by Wellington geological professor Rupert Sutherland detected 100-degree-centigrade (212 Fahrenheit) groundwater at 630 meters.

That is a groundwater temperature not normally reached until about 3 kilometers underground.

Pressure-cooker-like conditions underground keep groundwater liquid, however, unlike boiling water that vaporizes on the Earth's surface.

Whataroa lies near the Franz Josef Glacier, an alpine tourist attraction in a region also dependent economically on dairy farming in coastal valleys.

Energy source?

Sutherland speculated Wednesday that the Alpine Fault could become an energy source for local industry located along the fault-line.

"It's a totally new paradigm," he told Associated Press. "Economically, it could be very significant for New Zealand."

The central North Island's three largest volcanos

The Pacific Rim nation already has geothermal electricity facilities in the volcanic center of its North Island.

Implications for quake forecasts

Professor Bill Elsworth of California's Stanford University said the study's findings had important implications, because elevated fluid pressures underground tended to weaken faults.

The 500-kilometer-long Alpine Fault - marking where the Pacific and Australian tectonic plates collide - is expected to rupture in "an extreme magnitude 8 earthquake in the coming decades," warn the authors.

Such giant earthquakes have had a frequency in New Zealand of about 300 years. The fault's last magnitude-8 disruption occurred in 1717.

New Zealand's seismic GNS research center says the Alpine Fault lies in the nation's zone with the"most shear strain."

In 2003, an earthquake originating in the Puysegur ocean trench, off the South Island's remote Fjordland region, had a magnitude of 7.2.

Alarming projection

The Christchurch earthquake of February 2011 had a lower magnitude at 6.3, but still claimed 185 lives and left an economic recovery bill put at $NZ 40 billion (25 billion euros).

Last November's shallow Kaikoura earthquake, near the top eastern end of the South Island, killed two people and required New Zealand to make further repairs to wrecked infrastructure, including highways, and seek to rejuvenate tourism.

The country's capital Wellington is riddled with fault-lines, including one almost underlying its parliament building complex.

In March, Christchurch's main newspaper The Press published a dramatic scenario of an major Alpine Fault rupture.

"The energy released would be four times that of the Kaikoura earthquake, and 700 times that of the 2011 Christchurch earthquake," predicted The Press.