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Scientists Discover Promising Geothermal Activity in New Zealand Adapted from a Press Release by Victoria University of Wellington The Deep Fault Drilling Project jointly led by two universities in New Zealand, Victoria University of Wellington and the University of Otago, along with GNS Science, carried out drilling in 2014 in Westland, New Zealand. A team of more than 100 scientists from 12 countries were working to understand how earthquakes occur on geological faults. They drilled to a depth of nearly 3000 feet, revealing the potential for large geothermal resources in the area. The team identified the site as the best place in the world to understand what a fault looks, feels, and sounds like just before an earthquake occurs. The Alpine Fault is known to rupture in magnitude 8 earthquakes approximately every 300 years, plus or minus 90 years. WWDR has previously covered the project in the March 2015 article Scientific Drilling into the Alpine Fault Begins , and April 2016 article Alpine Fault Drilling Leads to Unexpected Results . New results for the project were published in 2017, and discuss the site’s geothermal gradient, which is how fast the temperature increases as the depth beneath the earth's surface increases. The team discovered water hot enough to boil at a depth of around 2000 feet. Similar geothermal tem- peratures are normally found at depths of nearly two miles. According to the lead scientist, Rupert Sutherland, the geothermal conditions discovered are extreme by global standards and comparable to those in major volcanic centers, but there are no volcanoes in Westland. Instead, the geothermal environ- ment is created by a combination of tectonic movement and groundwater flow. Slippage during earthquakes uplifted hot rocks from about 20 miles deep. The rate at which the rocks are lifted to the surface is so quick it doesn’t give the rocks a chance to cool properly. Because earthquakes fracture the rocks so extensively, water is able to infiltrate deep beneath the mountains, then heat, becoming concentrated in upwelling geothermal fluids beneath valleys. However, river gravels which are flushed by abundant rain and snow dilute this geothermal activity before it reaches the surface. Sutherland said, "Nobody on our team, or any of the scientists who reviewed our plans, predicted that it would be so hot down there. This geothermal activity may sound alarming, but it is a wonderful scientific finding that could be commercially very significant for New Zealand." It is still too early to determine how large and hot the geothermal resource might be, so additional exploration and drilling will be needed to assess the economic potential. Technologies used to gather the data us lasers and a fiber- optic cable installed in the borehole to gather precise temperature and seismic measurements. Ongoing work aims to develop these technologies, use the exist ing borehole to moni tor subt le changes, and search for new earth- quake-related phenomena. The fractured and strongly layered rocks, along with the extremely hot tem- peratures, provided engineering chal- lenges which hindered the project from achieving al l of i ts technical goals. However, many scientific measure- ments were taken and the borehole continues to provide interesting data. The findings reinforce the need for sci- entists to better understand conditions around geological faults which generate earthquakes. The Deep Fault Drilling Project site, courtesy of Victoria University of Wellington / John Townend. GEO 16 AUGUST 2018 WorldWide Drilling Resource ®