Could geothermal drilling cause an eruption?

Canlaon volcano, Philippines

Geothermal energy is one of those sources of energy that might be able to solve a lot of the planet's energy problems - heck, the Earth has a lot of heat it is trying to get rid of, so taking that heat and turning into energy seems like an easy (and clean?) way to stop using fossil fuels and the like. Of course, like any supposed panacea, it has its problems.

However, one aspect that gets people are riled is whether drilling into areas of active magmatism might actually cause volcanism. Just in the last few weeks, a controversy was sparked in the Philippines when 20 earthquakes were felt soon after drilling for a new geothermal prospect on Canlaon Volcano. Now, as many of you know, I love to remind people "correlation does not mean caustion" - that is, just because you had drilling and seismicity, it doesn't mean that the two are related. In fact, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) can't even determine whether the earthquakes were volcanic, tectonic or something else - mostly thanks to the fact that their equipment was being moved at the time. However, what can be said is that little to no seismicity has been recorded at Canlaon since these tremors at the end of March even with new seismometers in place around the volcano.

Canlaon is an active volcano, in fact the most active in the central Philippines, last erupting in 2006. Most of its eruptions produce VEI 1 or 2 explosive events with minor ash and phreatic explosions, but it has erupted at least 5 times in the last decade. With a volcano this active, it wouldn't be surprising to record seismicity, especially if an eruption might be in the works. PHIVOLCS thinks that the volcano is not headed towards eruption and that the tremors - whatever the cause - are not the result of the drillings as part of the Northern Negros Geothermal Production Field. However, some people who felt the tremors think otherwise, even suggesting a congressional inquiry into the tremors and their relation to the drilling and Canlaon. This would be a serious issue as Canloan (the volcano) is close to Canlaon City (population ~50,000). This is not a new accusation in the Philippines either, as the Aetas believed that drilling caused the 1991 eruption of Pinatubo (partial link that requires registration, sorry!), which was clearly not the case.

I would be very surprised if any human drilling possible today would have any effect on a system as large and complex as a volcano. There have been a number of research drilling programs that attempted to drill directly into the active parts of the volcano, such as the conduit at Unzen or the flanks of Kilauea/Mauna Loa. Neither of these drilling programs had any effect on the eruptive activity at the respective volcanoes. Sometimes, you do hit areas where steam can cause an explosion in the drill hole (such as the linked video in Iceland) and drilling is likely the cause of the infamous "mud volcano" in Indonesia, but these are related the water and heat rather than new movements of magma. It might be easy in one's mind to link geothermal drilling to any increase in "restlessness" at any volcano nearby, but there is no hard evidence that drilling can have such a direct effect on volcanism.

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When visiting Myvatn Iceland 9 years ago, we heard a tale of the Krafla Fires ( where geothermal drilling hit the shallow magma chamber and started lava flows. Now I've never seen this story confirmed anywhere, and in anycase the crust was actively rifting and lava would have erupted with any human aid.
Has anyone else heard this story?

Well, I happen to share an office right now with someone who works on Icelandic geothermal systems, and she tells me that yes, eruptive material has come out of a drill hole during the Krafla Fires:

... a miniature explosive event through a geothermal borehole produced about 26 m3 of tephra (â¼1 m3, DRE*) in the September 1977 eruption.

This is from Thordarson and Larsen (2007). The conclusion is not that the drilling produced the eruption, but rather magma from the eruption utilized the borehole to erupt. In any case, the 1 cubic meter of tephra relatively insignificant.

There are also some borehole in Iceland that have been refilled with lava after the borehole was drilled. Again, this isn't causing an eruption, but at least indicates that we can drilled into active magma chambers.

*DRE means "dense rock equivalent". Most volcanic tephra is full of air pockets, so converting to DRE is a way normalizes volume of volcanic eruptions by calculating a volume of magma if the volume of air pockets/bubbles is subtracted out.

{Hat tip to Naomi for the Iceland info.}

That's interesting. The local folklore (at least as told to us geo-tourists) did imply that that drilling caused the eruption, and I can see how progressive exaggeration of an actual event can reach the point where people start to say "drilling set off an eruption".

I recall reading of a scare at Nicaragua's Momotombo a few years back, when there was an earthquake swarm almost directly underneath a geothermal power plant on the volcano's flank; the plant was temporarily evacuated as a result. Momotombo has been inactive since 1905, but still has high-temperature fumaroles (700-800 degrees)

FAR from being any kind of expert in this field I can offer only two comments in this regard: Quoting Dr Richard Feynman (Nobel laurate in physics) in his analysis of the Challenger explosion, he said "It is wise to remember that nature cannot be fooled" Secondly. if it looks like a duck, walks like a duck and quacks like a duck, one can be pretty certain that it is duck. No matter what any computer model says.

There were a series of small eruptions south of Mývatn in the late 70s and early 80s, lots of little fissures popping open and belching out some lava.
Mostly "tourist eruptions", though some animals were lost.

A drill did hit a shallow magma channel and lava erupted out, destroying the rig and came very close to injuring some people, though if you had asked me I'd have said it happened in '83 or '84 when I was working up in the area.
I was not there the day it happened, but it was on the news at the time, and a high profile story locally, and I have talked to people who were there at the time.

The lava would have come up somewhere in the vicinity and very soon, but the proximate cause of the eruption then and there was indubitably the drilling.

This is all great! Thanks for that information, Steinn. It seems like Iceland might be the type locality for these sorts of events - however you might want to call them. I suppose its because Iceland is so magmatically active and there is so much geothermally drilling, but to hear that lava came up and destroyed the rig is fascinating ... so maybe, in the right circumstances, you can get an "eruption" from drilling, but it so far doesn't seem like you can "reactivate" an entire volcano by drilling.

Question: can the removal of water and oil from the earth's crust and/or the massive weight concentration of cities like New York affect the stability of the crust or the earth's spin?

By J A Slaymakr (not verified) on 09 Apr 2009 #permalink

Absolutly, you open up the a hole and you let the gases have a new way to escape. Hex, you might even open into a fisher and who knows what might happen then. I don't believe we need all this crap you are drilling for to live. They made it just fine 100 years ago or so without all this fossil fuel. All is necessary is electricity. And we can get that from running water with Hydro Plants. We don't need to fly, explore space, remove whats beneath the Earths surface, or clear-cut the forests to make paper to live on this planet. What we need to do is look back in History and see that living mildly with Nature and the Planet was fine and growing our own Food was a way of life that we should AGAIN partake in. The exploration of the earths inner sanctum and space should be left alone. We need not these things. And the holes left behind will certainly be the cause of someone's death.

By PENNY SLAY (not verified) on 11 Apr 2009 #permalink

Penny, people have been mining for millennia.

Fossil fuels certainly were used in significant quantities 100 years ago. Ever hear of coal?

There are large parts of the Earth where hydropower is not possible. And there is evidence large dams/reservoirs can cause earthquakes. So if you're arguing against drilling based on the rather flimsy guess boreholes might trigger eruptions or earthquakes, why propose somethingâhydroelectricityâwhich is essentially known to cause earthquakes?

And I do hope neither you nor the supplies you need nor the food (or whatever) you produce has to travel very far. Excepting electric trains, English milk floats and possibly a few other specialist examples, electric-powered vehicles are not, sadly, adequate. (Please note I do not own a car myself. I bicycle. My bicycle, made of metal from inside the Earth, was built by techniques (brazing et al.) which require fossil fuels, and was shipped to me by diesel truck. So was my computer. And, very probably, yours as well.)

This reminds me of the eternal question in the northern oil patch of Canada's two westernmost provinces.

Here we have an area that is not historically known for earthquakes. Along comes oil and gas exploration. Small earthquakes start occurring. People start asking the question, "Does seismic exploration cause these earthquakes?"

Then, time moves forward, oil supplies diminish and oil companies start "enhanced recovery" methods. One of these methods involves injecting steam and chemicals deep into the earth to force out pockets of oil.

Then comes the 5.4 earthquake of April 2001 in northern Alberta, near the B.C. border. National Resources Canada sends a letter to an oil company, pointedly asking if its steam injection techniques in the area are related to the earthquake. The company responds that these techniques are not known to cause earthquakes.

Who would ever do the research to prove that, yes, indeed, steam injection causes earthquakes? Certainly not oil companies. And so, citing lack of evidence that this procedure causes earthquakes, the earthquake is explained away.

Meanwhile, the common folk continue to mutter that seismic exploration/steam injection is responsible for these earthquakes, which did not occur before the resource extraction in the area.

This is a question we'll never answer. There is no will to know. We do know some historical facts of the harm caused by other mining efforts in the province. There is no doubt, for example, that Turtle Mountain collapsed, crushing a town and its people in the Frank Slide of 1903. With such a blatant example still staring us in the face, is it any wonder that people are somewhat cynical about these things, and unlikely to accept corporate brush-offs?

Fluid injection definitely causes earthquakes- small ones usually by increasing the fluid pressure that's exerted on the rock (that the fluid is being injected into)...Seems like steam could just as easily do something similar.

Changes in the water table definately cause earthquakes, as does hydrothermal activity; these may be responsible for most earthquake swarms.
The earth's rotation IS affected by man... all the reservoirs built in northern latitudes have collected water closer to the earth's axis, and thus accelerated the earth's rotation by an imperceptible, but measurable, amount.

Canlaon Volcano is located near my home country, Philippines. My parents house is overlooking this magnificent view of the volcano. For the last few weeks tremors were being felt, some where magnitude 4 in La Carlota City. I am a bit concerned of the family I left behind in the Philippines so in your studies, do you think an eruptions is imminent?

Here's one of the news clipping I got regarding the recurrence of small quakes being experience in last few weeks.…


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