Tag Archives: borehole

Project drills deep in New Zealand to understand and predict earthquakes

For the first time, geophysicist in New Zealand will place seismic sensors deep into a geological fault to record the build-up and occurrence of massive earthquakes, potentially giving crucial  information about one of the biggest faults in the world.

It’s hard to say anything after such an insightful and well explained video. The Alpine Fault runs for about 600 kilometres along the west coast of South Island, marking the boundary between the Pacific and Australian tectonic plates. It is a planar discontinuity over a huge volume of rock, across which there has been significant displacement – see the mountains.

Every year, the two tectonic plates slide by each other by about 2.5 centimeters; it may not seem like much, but just think of the incredibly massive volumes which are sliding this way, creating friction and building up pressure – and just think what the effects will be over hundreds of years. Geologists are confident that the fault is “ready to break in its next earthquake” — with a 28% chance of a rupture in the coming 50 years, which is another reason why this project is so important.

“If we go on to record the next earthquake, then our experiment will be very, very special,” says Rupert Sutherland, a tectonic geologist at New Zealand’s Institute of Geological and Nuclear Sciences in Lower Hutt, and one of the project’s leaders. “A complete record of events leading up to and during a large earthquake could provide a basis for earthquake forecasting in other geological faults.”

The costs of the project are $2 million, which are not that high when you consider the potential implications. The first step is to collect geological samples, then dig a shallow borehole and insert sensors into it. The hole will then be deepened and strengthened, and after this, more seismic sensors will be added. This will hopefully be done by December. Then, the data will be directly analyzed and inserted into computer models of faults, in order to better understand when and how faults break, and how this is foreshadowed.

For example, one idea is that large differences in groundwater pressures on either side of the fault zone could indicate that a big quake is imminent.

“The fault appears to currently form an impermeable barrier, and it’s likely that time-dependent differences in groundwater pressure on either side of the fault play a role in governing earthquake nucleation processes and the radiation of seismic waves,” says John Townend, a seismologist at Victoria University of Wellington, who is part of the project.

The World’s Deepest Hole Lies Beneath this Rusty Metal Cap – The Kola Superdeep Borehole

Would you believe me if I told you that under this rusty, abandoned metal cap there lies the deepest hole ever dug by mankind? That beneath this metal seal, which measures only 9 inches in diameter, there are 12,262 meters (40,230 ft) of nothingness? You might have your doubts — but hear me out.

A journey to the center of the Earth

During the Cold War, the race for space took all the headlines, but the digging race was equally competitive (digging boreholes, that is). This is the Kola Superdeep Borehole – a project funded by the USSR and then Russia between 1970 and 1994. In that period, geologists and geophysicists had only indirect evidence as to what was going on in the Earth’s crust, and superdeep boreholes provided much-needed information for a better understanding of the underlying geology by utilizing direct observation. Even to this day, information gathered by this project is still being analyzed and interpreted.

Granites… granites everywhere

The first surprise they encountered was the lack of the so-called “basaltic layer” at about 7 km deep. Previously, the best geological information about the deeper parts of the crust came from analyzing seismic waves, and the waves suggested a discontinuity — basically, they were expecting to find granites, and as they went deeper, basalts. But much to everybody’s surprise, when they went deeper, they actually found… more granites. As it turns out, the seismic discontinuity was caused by the metamorphosis of the granites, not by basalts.

Water?!

A photograph depicting the operation of the drilling — not the best quality, but you get the picture.

As if that wasn’t enough, between 3 and 6 km deep, they also found water. By the knowledge we had back then, water simply shouldn’t have existed at those depth – and yet, there it was. Now we understand that even deep granites can get fractured, and those fractures can get filled with water. Technically speaking the water is just hydrgen and oxygem atoms squeezed out by the enormous pressures caused by the depth – and trapped in impermeable “layers” of rock.

Boiling with hydrogen

Researchers also reported the extraction of mud, which was “boiling with hydrogen” – such large quantities of hydrogen at these depths were completely unexpected.

Life — deep inside the Earth?

Without a doubt, the biggest surprise was the discovery of life: microscopic plankton fossils in rocks over two billion years old, found four miles beneath the surface. These “microfossils” represented about 24 ancient species and were encased in organic compounds which somehow survived the extreme pressures and temperatures so far beneath the Earth’s surface. This raised numerous questions about the potential survival of life forms at impressive depths.

Now, research has shown that life can exist even in oceanic crust, and even macroscopic life was found at over 1 km deep, but at the time, finding those fossils came as a shocker.

Abandoned, but not forgotten

Now, the Kola Superdeep Borehole is all but abandoned. At depths in excess of about 10,000 feet, researchers started to notice that the temperature increased faster than expected, and the first problems started to occur.  In 1983, the drill passed 12,000 m (39,000 ft), and drilling was stopped for about a year to “celebrate” the event. I have no idea why they would stop for a year to “celebrate”, but this idle period probably contributed to the breakdown in September 1984: after drilling to 12,066 m (39,587 ft), a 5,000 m (16,000 ft) section of the drill string twisted off and was left in the hole. Drilling was later restarted from 7,000 m (23,000 ft).

The drill bit used in the digging process (one of them). The nearby town of Zapolyarny holds the Kola Core Repository, which displays rock samples obtained during the drilling operation.

However, temperatures continued to grow more than the expected values, and by the time the hole reached its maximum length, the temperature was a whopping 180 °C (356 °F) instead of expected 100 °C (212 °F). The drill bit could no longer work at such temperatures, and drilling was stopped in 1992.

The entire project was closed down in 2005 due to (you’ve guessed it) of lack of funding. All the drilling and research equipment was scrapped and while data produced by the Kola drilling project continues to be analyzed, the site itself has been abandoned since 2008; the hole was welded shut by the metal cap we still see today, as if to seal off any devils or mysteries that might lurk beneath.

You can visit the now-abandoned site but, unfortunately, you won’t be able to peek through the hole that, to this day, is the deepest hole dug below the surface.