The risks may be small, but a technique called an enhanced geothermal system (EGS) has the potential to cause damaging earthquakes. Here in Oregon, Davenport Energy has proposed using an EGS technique to look for geothermal energy next to Newberry Crater. More on that later.

The warning comes from a supporter of geothermal energy who says he’s not trying to be an alarmist. Rather he says, he wants to avoid a backlash against EGS because of its amazing potential to supply clean energy just about anywhere.

The Navy 1 geothermal power plant near Coso Hot Springs, California, is applying EGS technology. Photo from Department of Energy.

Traditional geothermal techniques use hot water produced by earth for heating and generating electricity. A classic example are the hot springs that dot Oregon’s countryside. Near Newberry, when Davenport power went looking for geothermal energy they didn’t find much hot water, but they did find hot rocks. That’s the kind of situation EGS is designed to exploit. Water is pumped down the well to be heated by the rocks, then withdrawn as an energy source.

The process fractures the hot rocks beneath the surface, making it easier to circulate the water. But the fracturing also causes small earthquakes that can be felt by people on the surface. In rare cases, the quakes are big enough to cause damage.

Writing in tomorrow’s issue of Nature, Domenico Giardini of the Swiss Seismological Service, uses a case study from Basel, Switzerland as an example of what can go wrong. In December of 2006, the area was rattled by thousands of micro-quakes when water was pumped down a geothermal well for the first time.

The seismic activity was strong enough to convince officials to stop pumping water the next day. But it wasn’t soon enough. Later that day, a magnitude 3.4 quake shook the area, spreading fear and anger among the public. Since then, insurance payouts on the damage have totaled more than $9 million. Giardini notes that many of the claims were for non-structural problems such as cracks in plaster.

The lesson here, according to Giardini, is that “the public reacts with a vengeance if it perceives that a known problem has been hidden.” He goes on to say, “The risk of overreaction (to EGS projects) is very real. The establishment of an overly harsh regulatory framework would penalize the geothermal industry in comparison to other energy sectors.”

How much potential is there in EGS? Giardini cites a 2006 study produced at MIT that concluded EGS could provide 100,000 megawatts in the United States by 2050. That’s about 10% of current electrical production. The federal government has committed more than $132 million to EGS demonstration projects around the country.

If you drill deep enough, you should be able to find hot rock just about anywhere, including areas where lots of people live. Deep EGS projects could potentially be located in cities. But also raises the risks, no matter how small they may be.

Giardini says these risks have to be discussed openly by officials with the public. He says its important to figure out ahead of time how payment for damages will be handled and how much risk is acceptable to the public. “Otherwise,” he writes, “society risks a public backlash that could unnecessarity quash a promising alternative-energy technology.”

Giardini’s Opinion Piece will be published in the December 17 issue of Nature.

For more on the geothermal exploration near Newberry Crater, see the recent article on the Bend Bulletin, Geothermal drilling might SHAKE Newberry.

Had you been onshore at the time, you wouldn’t have noticed a thing.  The quakes were too deep and too far away to be felt on land.  But even though they were harmless to people, the quakes were strange enough to make international news.

Scientists at Oregon State University now think they’ve figure out what happened.

Earthquake swarms off the Oregon coast are not that unusual by themselves.  There have been eight recorded swarms over the past dozen years. But the first swarm of last Spring was different because it happened inside the Juan de Fuca plate.  Most quake activity in this area happens along the plate boundary.

The Earthquake Detectives

When the first swarm was detected, OSU dispatched the research vessel Wecoma to the quake area to take water samples and look for signs of volcanic activity on the ocean floor.  Swarms are often caused by volcanic activity, so in a sense the scientists were looking for the “usual suspect”.

Then in September of that year, other scientists returned on the research vessel Melville.  Using a multi-beam sonar, they remapped the ocean bottom.  And that’s when they discovered a new system of earthquake faults.  OSU researcher Susan Merle was aboard the trip and recalls seeing a 20-meter (or about 60 feet) displacement of the seafloor.

“That’s a pretty big fault,” says OSU Marine Geologist Bob Dziak. He says it shows that the Juan de Fuca plate is “being squeezed” by the Pacific plate to the west and the continental plate to the east.  “It isn’t clear if the swarms that occurred in 2008 represent normal stress release within the plate, or if they are from deformation related to the Cascadia Subduction Zone. We simply don’t yet know.”

As For Those Other Swarms

The following swarms occured along plate boundaries, areas that are more likely to see quake activity.  This follow up activity was, in some ways, even more intense than the first swarm.  In an area called the Gorda Ridge, scientists recorded more than 1000 quakes in just five days.

One of the questions the scientists are trying to answer is, are the two events related?

Dziak seems to think they are.  ”But,” he says, “we don’t yet completely understand how they are related and what triggers the sequence. But it is interesting that the stress release within the plate could trigger swarms of earthquakes on the plate boundaries.”

What really happened today is that OSU tested its new hurricane wavemaker at the Hinsdale Wave Research Laboratory. The $1.1 million dollar simulator is designed to show how long shallow waves, the type created by tsunamis and sustained hurricanes, will impact coastal areas. It’s the largest simulator of its kind in the country.

The demo kicks off a series of research projects starting this summer. One of the first will study how wooden structures, which are common on the Oregon coast, will hold up during tsunami events. Figuring that out is important. Earlier research by OSU shows that the fastest way to evacuate from a tsunami isn’t running away, but going up. That is, going to the top levels or roofs of buildings. But if the buildings can’t withstand tsunami force waves, then the whole evacuating up idea isn’t going to work.

OSU released this video of today’s demonstration. The first highlight comes at about 25 seconds.

There’s also a high rez version at http://oregonstate.edu/media/twvwz-hiq.

According to Hinsdale Lab Director Dan Cox, the real value of this new simulator is the size of the waves it creates.

“Because the materials used for coastal construction – wood, concrete and steel – have complicated properties, they cannot be studied easily at small scale,” says Cox. “The new wavemaker is bigger and improves the accuracy of our research and applicability to real-world structures.”

Other research projects coming up include, a study on how hurricane force waves can overtop levees and the damage it does, and another study looking at the impact of these waves on coastal vegetation.

The money for the new simulator came from the National Science Foundation.