Can a huge geothermal power plant cause an earthquake?

April 6, 2010 8:11 PM

As I understand it, the 7.2 earthquake that hit Mexico last weekend had it's epicenter in Guadalupe Victoria, which is just a few miles from Cerro Prieto, a dormant volcano and the worlds largest Geothermal plant. Is there any scientific (not tinfoil hat) evidence that having a large scale Geothermal plant, doing whatever it is Geothermal plants specifically do, could lead to or worsen an earthquake? And if the volcano is dormant, how is the plant generating power? Does dormant just mean not spewing lava actively, but there is activity underneath?

Satellite of the location in question.

posted by Spurious Packets to science & nature (13 answers total)

A link from your wiki link suggests that there may be a link with Enhanced Geothermal systems http://en.wikipedia.org/wiki/Geothermal_power
posted by defcom1 at 8:32 PM on April 6, 2010

The Pacific Plate is moving northwest and the North American Plate is slowly moving west at this point but not as quickly, hence the San Andreas system of faults. The movement creates tensions which release via earthquakes. This is why Baja California is separated from the rest of Mexico.

I would think that a major plate boundary would trump, in scope, whatever a geothermal plant could do.

Not that these plants are benign. . . .Locally, we have kept any from being built around Crater Lake, out of concern that it would mess with the lake's equilibrium.
posted by Danf at 8:52 PM on April 6, 2010

There is indeed evidence that geothermal power projects can trigger, and have triggered, earthquakes.

In 2006, a geothermal power plant in Switzerland triggered a magitude 3.4 earthquake, followed by dozens of aftershocks. The engineers did inform the public that the Deep Heat Mining project could trigger small tremors, however quakes of the magnitude experienced were not anticipated. The head of that project, Markus Haering at Geopower Basel, faced five years in prison for property damage in the nearby town of Basel. The company has already paid about $9 million in compensation damages for the quakes.

Landau in der Pfalz, a small city in Germany, is currently undergoing government inspections about earthquakes potentially caused by a geothermal plant built by Geox, a German energy company. German scientists suggest that an earthquake that happened in August was a direct result of the geothermal plant.

Late last year, a US firm scuttled its plans to install a geothermal plant due to concerns about setting off earthquakes at the Geysers, a geologically active area 70 miles north of San Franscisco. AltaRock Energy was the Obama adminstration's first test of geothermal energy as an alternative to fossil fuels.

As a result of the AltaRock project, the US Department of Energy (DoE) is imposing new safety regulations on geothermal energy projects to address concerns that the activities could increase local earthquake risks.

POWER Magazine recently ran a fascinating article that rounds up many of the seismic events near geothermal plants: "Assessing the Earthquake Risk of Enhanced Geothermal Systems".
posted by prinado at 8:54 PM on April 6, 2010 [4 favorites]

To answer part of your question:

One of the simpler ways to answer is that an active volcano is one that has erupted since the last ice age (i.e., in the past ~10,000 years). That is the definition of active used by the Smithsonian in their catalogs. A dormant volcano would then be one that hasn’t erupted in the past 10,000 years, but which is expected to erupt again. An extinct volcano would be one that nobody expects to ever erupt again. These are human definitions of natural things – there have been a number of eruptions from “extinct” volcanoes!

http://blogs.oregonstate.edu/volcanofaq/2009/05/08/how-is-a-volcano-defined-as-being-active-dormant-or-extinct/

Near volcanos, even dormant ones, magma is closer to the surface of the Earth, which results in more opportunities to collect geothermal energy. Volcanoes also tend to fall along plate boundaries, which are geologically unstable regions - thus, you also get a lot of earthquakes there anyway.

This Scientific American interview with a geologist seems to indicate that yes, geothermal drilling can cause minor earthquakes. Note that this doesn't mean that it did have anything to do with the Mexico earthquake.
posted by chrisamiller at 9:00 PM on April 6, 2010 [1 favorite]

Off the top of my head, I would say that the earthquake was more likely caused by the volcano waking up. But then I remembered when I was in Baja recently I heard talk of the plant causing tremors and other problems that I don't quite remember, mostly because the beer is cheap and cold. So I googled it and it seems that there is discussion of the geothermal plant as being the cause.
posted by Duffington at 9:02 PM on April 6, 2010

This earthquake was on the main San Andreas fault. It isn't necessary to go looking for obscure reasons for it; the San Andreas does that kind of thing all on its own.
posted by Chocolate Pickle at 10:17 PM on April 6, 2010

Geothermal power works because magma (hot, molten rock) has risen higher than it normally does. This usually happens on plate boundaries, as the subducting plate melts and then rises. Sometimes the magma can rise all the way to the surface and make a volcano. Sometimes it doens't get that far, and the mixing of ground water with magmatic fluid gets some crazy boiling action happening, and this can fracture all sorts of rocks (this is an epithermal system).

A volcano can be dormant but still sit above hot ground. One possibility is that for a while a magma pluton (think of a big rising plume of magma through the crust) was supplied by the subducting plate. This stops at some point (plates can stop subducting if they really want to), so for a long while the tail of that magma pluton rises up and the volcano on top keeps going. At some point, there's not enough juice left in the pluton to pop the plug on the volcano, so it won't erupt again. There's still a giant pool of hot rock sitting below the surface, very happy to heat some water if you let it.

As for geothermal power creating earthquakes, the links above are pretty spot on. Essentially, much epithermal energy works by lubricating a fault. The only reason a known fault doesn't move all the time is that it takes a huge amount of energy to shove that much rock against itself. If you pump the fault full of fluid, you lubricate it and reduce the energy needed to cause a quake.
posted by twirlypen at 11:28 PM on April 6, 2010

That Swiss geoengineer was acquitted of all charges, by the way.
posted by cromagnon at 11:50 PM on April 6, 2010

I am not a Geologist, but I am a bit skeptical about some of the cause and effect assumptions here.

Do Geothermal plants cause earthquakes?

Geothermal power works because magma (hot, molten rock) has risen higher than it normally does.

Well, let's assume that Geothermal plants tend to be built in areas where the magma is closer to the surface than usual: do these areas tend to have higher levels of seismologic activity than usual?
posted by ovvl at 4:45 AM on April 7, 2010

I think there might be a correlation versus causation problem here. Yes, drilling a hole into a rock that is under tremendous pressure/tension might *hasten* an earthquake, but the pressure was already there. The plates are always moving, and grind against each other. When they get stuck, the plates continue moving, but the material on the edges twists and stretches like a spring. It is very nearly the immovable object versus the unstoppable force question. So there comes a point when the nearly immovable object breaks loose and the spring sproings.
posted by gjc at 6:06 AM on April 7, 2010

Here's more about induced seismicity at The Geysers, including a nifty map.

The Geysers geothermal field in northern California is the largest single geothermal field in the world. (Over 800 MW in 2009 and increasing as EGS activities carry forward). Seismicity related to production and injection has been observed since the 1970’s and has been used as a general indicator of fluid paths and reservoir response. An increase in injection rates using wastewater from the areas of Santa Rosa and Lake County, CA have recently raised concerns regarding the impact of injection related seismicity on nearby communities.
posted by rtha at 6:54 AM on April 7, 2010

We actually discussed this during my undergrad days studying engineering and geology. In a strike/slip zone (such as baja up through california) it most certainly can and has been proven during research in the 60's in california. They found that while injecting water into an active fault system can induce earthquakes, the magnitudes are so small compared to a big earthquake that it makes no difference unless you are causing continous little ones and even then you are only postponing a big one. The richter system is logarithmic, hence a 3.4 is not half as powerful as a 6.8 it is 10^4 less powerful. Big earthquakes are going to happen along a plate boundary no matter what you do. We have just had a string of big ones recently near populated areas or areas of concern to the US. Big earthquakes happen every year, they just don't usually get big headlines as most happen underwater and don't cause tsunamis. I would think it much more likely that the big earthquakes around the permiter of the american plates are related than a geothermal plant set off this one, which btw didn't cause that much death and/or destruction due to its happening far from any major population centers.
posted by bartonlong at 8:57 AM on April 7, 2010

Well, let's assume that Geothermal plants tend to be built in areas where the magma is closer to the surface than usual: do these areas tend to have higher levels of seismologic activity than usual?

Sometimes. If there's a lot of seismicity, then there's a lot of faulting, then there are a lot of (comparatively) weak conduits through which a pluton can rise. Sometimes it'll just come up through softer, weaker sediments though, and have nothing to do with seismicity.

I think gjc has nailed it though- while geothermal energy activities may hasten a smaller earthquake, they aren't going to do anything to avoid or initiate the big ones.
posted by twirlypen at 10:09 PM on April 7, 2010