Extreme Heat, Fluid Pressure Discovered at New Zealand’s Most Hazardous Earthquake-Generating Fault
A team of researchers from more than 10 countries found that deep within New Zealand's most hazardous earthquake-generating fault hides a region with extreme hot temperatures and high fluid pressures.
Their discovery, published in the journal Nature, could help in determining the mechanism behind the build-up of major earthquakes. Additionally, the extreme conditions within the fault have the potential to become a new type of geothermal energy source.
"We can now describe and estimate conditions on a geological fault that will rupture in an earthquake. This will help us to develop better computer models of earthquake rupture," wrote Rupert Sutherland, a professor of tectonics and geophysics at Victoria University of Wellington and one of the researchers, in an article posted at The Conversation. "It may also help us to explain how some types of geology (for example certain types of gold mineralisation) have formed as a result of similar conditions in ancient earthquakes."
As part of the "Deep Fault Drilling Project," over 100 scientists from 12 countries drilled holes into the Alpine Fault. They drilled two holes, with their second attempt reaching up to 893 meters deep. Interestingly, as the team dig deeper into the fault, the temperature rises at a surprising rate.
Normally, temperate rises at a rate of 3 degree Celsius per 100 meters in depth. However, the temperature deep within the Alpine fault increases at 15 degree Celsius per 100 meters in depth. At that rate, the water at the depth of 630 meters will be hot enough to boil at the surface. The high pressure at that depth is preventing the water from boiling.
Alpine fault is considered to be one of the major plate boundaries in the world. The fault runs for 650 kilometers along the South Island. The fault is capable of producing a magnitude 8 earthquake every 300 years. With its last rupture occurring on 1717, the Alpine fault is expected to rupture into a major earthquake in the next few decades.