Does Fracking Cause Earthquakes?
Drilling natural gas in Pennsylvania's Marcellus shale (Photo credit: Wikimedia)
This week my Skeptoid episode was about fracking, short for hydraulic fracturing, the controversial mining technique for deep natural gas deposits. The shock doc Gasland put fracking into the public eye, and not in a very complimentary way. Gasland blamed fracking for putting flammable methane into tap water, for mysterious illnesses caused by its “toxic” fluids, contaminating ground water with poisons, and killing animals, in addition to a host of political conspiracy charges. If you’re wondering why this decades-old practice did not seem to cause any problems before Gasland came out, it’s because Gasland was largely fictional. Most of its charges are based on real phenomena, but fracking itself rarely has anything to do with them. That’s not to say there are no environmental concerns about the practice. There are, to be sure; and the EPA is in the midst of a major study to find out how serious these concerns are. Some of these were discussed in my episode. One, in particular, I omitted: the question of whether fracking causes earthquakes.
It doesn’t sound entirely implausible. Some fracking operations extend for as long as kilometer horizontally through strata several kilometers underground, and add pressure in the same way a hydraulic ram works. It’s enough the actually crack the rock layer. These cracks are then filled with sand to hold them in place. It sounds like such huge pressures might well trigger an earthquake in a zone that already has some stress from natural gas extraction that has caused underground pressure changes.
And, in fact, fracking does unquestionably cause earthquakes: tiny ones. Every time a rock cracks underground, it’s a seismic event. When a kilometer of shale is fracked, that’s a lot of seismic events. But they’re really small, and don’t have anything to do with natural fault lines.
Here’s a quick explanation of why I didn’t cover this question in my episode. It was in my notes from the beginning, and a quick read of Wikipedia or other online sources is likely to confirm the connection between major quakes (larger than 3.0) and fracking. But as I did research and spoke with geologists, regulators, and people in the drilling industry, I quickly learned that it’s something nobody takes seriously. My experience was anecdotal, but to those in the know it’s something of an old joke. So, when my episode was running long (as most of them do), I had to cut something (as usual), and earthquakes were what I redlined from my notes. I assumed the claim was oddball enough that it wasn’t something real people were actually concerned about.
I was in error. Fracking and earthquakes was the subject of many tweets and emails I received. Why didn’t I go into this? What was I trying to cover up?
24 hours after my episode came out, I was faced with an entire screen full of email notifications that someone had cancelled a recurring donation to Skeptoid. The fracking episode had caused unprecedented anger among many listeners. I’m pleased to note that all the communications I’ve received from people who are knowledgeable about fracking, including people working in drilling, former anti-fracking activists, state and federal regulators, and geologists of several stripes, all told me that my episode was spot-on. However that’s small comfort for having driven away so many of my supporters.
Here is abbreviated coverage of my understanding of fracking and earthquakes, based on the small amount of research I’d done on it before cutting it out. Shale, which is the main kind of rock in which fracking is performed, is fragile. It splits easily. If a shale bed is under tectonic stress, it gives readily. Large tectonic pressures will not build up behind shale. Fracking the shale to break it up is unlikely to relieve any massive forces; as a pressure barrier, shale is a dog that won’t hunt. (I did limited research and have no personal expertise in this area, so I invite any and all corrections from the geologically proficient.)
The point of fracking is not to make the shale unstable, but rather to open it up in a stable way. All that sand does effectively hold the fractures open, as intended, and does not result in an unstable layer. It’s not like it will suddenly all collapse and cause an earthquake. Remember, we’re really deep underground, and the pressures holding everything in place are immense.
In lieu of discussing earthquakes in the episode, I put a really good newspaper article in my References & Further Reading section on the web site. If you’re interested in the earthquake question, you should read that article. But here’s a summary. There was a lot of concern that fracking had caused the August 23, 2011 earthquake in Virginia, which was a 5.8 — damn big and unusual for that region.
What has caused earthquakes in the past is not fracking, but a superficially similar practice: that of disposing of waste liquids in deep (really deep) drilling holes. If you drill one of these through a fault zone, you can (a) lubricate it, and also (b) put a lot of pressure down there. Things might go, and have, on occasion (this procedure is now required to undergo strict review by the EPA to make sure there are no faults around). But fracking is different. Fracking drills horizontally through natural gas containing shale, not through hard rock fault zones. But in some cases, used fracking fluid has been transported and disposed of in such wells, thus potentially causing an earthquake. That’s about as close as we can get to connecting fracking with earthquakes.
As far as this particular earthquake goes? I quote from the article:
For Virginia officials, the conclusive proof that drilling did not cause last month’s quake is that no well — for natural gas extraction or fluid waste — exists within at least 150 miles of the quake’s epicenter. Pressure would have had to cross at least two major thrust faults and several smaller ones to travel from Marcellus shale drilling in the Appalachian Basin and affect the Central Virginia seismic zone in the Piedmont, said David B. Spears, Virginia’s state geologist.
“There’s just no way any kind of drilling or hydrofracturing in those wells could be physically transmitted through the Earth over such a great distance. It’s just physically impossible,” Spears said. “With eighth-grade physical science you can figure this out. It’s just way, way, way too far and completely geologically isolated by multiple barriers.”
The Marcellus formation lies in one of the least seismic zones in the world, said Helen L. Delano, a senior geologic scientist in Pennsylvania’s Department of Conservation and Natural Resources. The risk for earthquakes is minimal, even without drilling.
I believe there are enough questions about fracking to justify a good documentary film that explores what we actually know and what we’re still learning. Too bad it won’t be made: sadly, Gasland has already poisoned that well.
As a seismologist, I wish earthquakes were that predictable.
Dunning’s not telling the whole truth, as I noted on that latest Skeptoid episode, too. For example, both here and there, he doesn’t even mention the 1987 EPA study that showed that at least in one case, fracking CAN contaminate water supplies.
http://www.nytimes.com/2011/08/04/us/04natgas.html?pagewanted=3
Sorry, but once again, Dunning’s not telling the whole story.
He never said that fracking cannot contaminate water supplies, so your “CAN” is dishonest. he wrote “fracking itself rarely [not never] has anything to do with them. That’s not to say there are no environmental concerns about the practice.” He point was misrepresentation by Gasland which has, as he said, “poisoned the well” of an honest investigation. The corporations have money, power to get what the want, but if we want to affect policy, we need to be armed with the truth and not just ideology.
Very true. Along with paying out people to buy their toxic land, the oil & gas industry also gets them to sign a gag order so they can never talk about it again. That doesn’t stop people around them from seeing what’s going on and talking about it.
As with all things, there are risks associated with fracking, and monied interests are going to great lengths to oppose regulation. But your podcast managed to convince me that most of the claims associated with fracking are baseless.
I’m still concerned about the chemicals used. Industry is still opposing even the simplest, most common sense regulations on that front.
Although many (not all) people involved would express a wish for regulation to go away, that’s simply not going to happen. The fact is that the industry will accept whatever regulation is put on it. The biggest complaint I hear regarding regulation isn’t that it should go away but that it isn’t uniform across states (the application process for exploration and production permits is very different in every jurisdiction).
There are numerous regulations governing the oil and gas industry. You’ll have to give an example of “opposing even the simplest, most common sense regulations on that front”.
Whatever they can’t get away with, they just cover it up. A catskinner told me that the oil company didn’t want to spend all that money for reclamation of the soil so he was ordered to just bury it. That really disturbed him so he went and told the farmer whose land the lease was on. Not sure if the farmer initiated a lawsuit. This is just one story, there are many many more just like it.
“The fact is … You’ll have to give an example …”
Double standard much?
“on that front”
Do you understand what that referred to? You write as if you don’t, or as if itzac never wrote it.
“the application process for exploration and production permits is very different in every jurisdiction”
And being as poor as they are, the petro corps are understaffed to handle it, eh?
Causing an `earthquake’? As you say, not the likely result of fracking. Isn’t it more likely that an environment conducive for underground disturbance/earth movement has been created??? Perhaps this is just semantics… but, an earthquake is an earthquake is an earthquake, an entirely different thing.
He covered that in detail in this article.
Fracking of course causes microseisms but I don’t know anyone who would call those “earthquakes”. Earthquakes are strike-slip etc. along a large fault and the energies involved simply dwarf the energies in fracking. One thing a lot of people don’t realize is that there are tiny faults pretty much everywhere and in fact faulting is one of the mechanisms for trapping gas. Gas people are continuing to do a lot of research into fault reactivation for a number of reasons, including the fact that for well over 40 years gas companies have been using depleted formations for temporary storage of gas – if you overpressurize the formation and reactivate a fault, you’ll lose a hell of a lot of money due to the gas which will no longer be recoverable and you may even have to consider abandoning that natural storage facility.
The list of substances used in the ‘fracking fluid’ are published and readily available. You can safely ingest small amounts of most of the substances used; none are particularly hazardous. Methane in drinking water? Hell, I’ve seen dozens of cases in areas where there isn’t any fracking going on. Some aquifers simply have huge amounts of methane and/or CO2 trapped in them. Can the fracking fluid etc. get into a potable aquifer? Sure, if the people doing the feasibility study are incompetent and don’t assure that there are extra ‘seals’ in the event that the operations should damage the ‘primary seal’. The operators in turn really don’t want to damage the primary seal because that means money lost. The biggest issue in places where there has been previous exploration are so-called ‘wildcat bores’ – old abandoned wells which are not necessarily abandoned according to current best practice or which have simply deteriorated with time. Given the historical requirements of record keeping etc., in most cases it is simply not possible to know where all these abandoned holes are. That may sound more grim than it actually is – you only need to be concerned with unknown holes in the region which you will be affecting with your operations. The vast majority of environmental concerns are items which the oil and gas industry has had to deal with for over 60 years (storage and handling of produced fluids, etc).
I think you should test your theory about frac fluids being non hazardous. Would you drink that everyday for a year and let us know how it works out for you?
Oh yeah, each time I drink Gatorade I’m drinking one of the primary components of fracking fluid. When I eat potato chips I’m ingesting more components. If I eat certain types of commercially prepared bread I’m eating yet another component of the fluid. In fact almost all the components can be found in some food or other.
“Frackin’ Snacks” has a nice ring to it!
Hey, I might steal that name – I’m a member of the Big Food conspiracy too, you know.
Just make sure that I get my cut.
“Frakin’ Snacks:
The quick pick-me-up for when you run outta gas!”
I didn’t realize there was N2 in gatorade. But come on, show us what you’re made of (oh I guess you already have, gatorade and chips, how much do you weight???). Do your duty to science and drink that crap for a whole year. You don’t want to disappoint your fellow scientists, do you? After all you did say fac fluid was non hazardous. Now is the time to put your money where your mouth is.
N2? What the hell are you talking about Sheila? You obviously live in an alternate reality. There’s plenty of N2 in Gatorade and I breathe it in all the time – it’s never done me any harm. There’s N2 in the frack fluid as well although it’s not added in, it’s just there.
N2 is added into frac fluid and so are a lot of other chemicals. But that just proves you don’t know what you’re talking about if you don’t even know that simple fact. N2 comes in barrels, but since you’ve never been on a lease, how could I expect you to know that?
What do you have against nitrogen gas? It makes up like 90% of the atmosphere.
Speculative ad hominem attacks, you really must have the facts on your side if you’re resulting to that 9_9
Look Sheila, “N2″ is nothing harmful at all – otherwise you’d be long dead a long time ago. Now why don’t you actually give us the sources of your misinformation rather than just prattling on here while people go “WTF is she going on about?” First of all, I’d like to know what this “N2″ you keep going on about is – what chemists know as “N2″ isn’t toxic. I’ve never seen a list of fracking chemicals with any “N2″ in it although as I said, the stuff chemists know as “N2″ would be in the fluid simply because it is, and not because it’s added.
I’m not going to say this again, N2 is added. Of course you’ve never seen a list which includes N2. Why do you think that is? Do you think it is possible that they aren’t telling people everything that’s going down the hole? What a freaking shock that is. So I suggest that you get off your ass and get out to a lease and see for yourself and quit arguing when you don’t know what you’re talking about. But that’s good that you believe everything that the oil industry spews because that’s the way it’s supposed to work. Don’t you feel stupid?
Another thing, my source (who I cannot name) is the one putting N2 in the frac fluid along with methanol and a whole host of other chemicals which are not listed by the oil industry. What kind of scientist are you madscientist when you refuse to believe anything that isn’t written in stone on the internet? And since you refuse to find out for yourself, please continue to pretend you know what you’re talking about.
Hey Sheila, where’s your evidence – at least a good photo from a site or something. It can’t be hard; the perimeter fence isn’t that big around. You’re just scaremongering with your unsubstantiated claims. I’m a good scientist – if I were to listen to you with your claims without evidence that would make me a bad scientist.
I really don’t want you to believe me. If you are a “good scientist” like you claim, you would find out for yourself. After you’re done, come back and tell me I was right. No amount of pictures is going to change your mind, because you’ve already made it up. I’m done with you. Unless you want to hear more oilfield horror stories, I have plenty?
Oh, poor Sheila – you’ll believe any conspiracy story, won’t you? You got your info from some “Source X” whom you can’t name (why not – will Big Gas hunt down your source), you mention a Secret Chemical and you can’t even tell us something so simple as what the markings on the container are. No photos, no evidence that anyone can follow up on, just vague assertions that somehow you know something.
Oh poor madscientist who refuses to get off his ass and do his own research. Please continue to sit in your stench in your basement. And why are you here anyway madscientist? You’re not even a damn skeptic. Just a wannabe scientist who can’t leave the house. Good job! And please continue to believe everything that oil & gas tells you because you’re such a good little scientist.
I just asked the person in question if I could use his name and the company he works for. He said no because the last time he voiced his concerns to the company he worked for about them burning PCBs in a kiln a mile away from town, he got fired. So other than the people he told, no one else was aware of what was going on in their backyard. This still holds true today.
And now back to you madscientist, such a good little minion.
Well there’s the problem Sheila – it’s all hearsay. You have these magical sources which cannot be named, no photographic evidence, you quote mysterious chemicals, etc. Burning PCBs in a *kiln*? Damn, you’re clueless. You’re either making up your sources on the fly without so much as asking Google for information to check that what you say makes any sense whatsoever, or you’ve got a pal who like to tell you tall stories. What you’re saying is just so out of whack with reality.
Holy crap, you expect me to hold your hand while I walk you through this? You don’t even have a clue what a kiln is? Please google fucking retard and I’m sure you will find your name listed.
Hey Sheila, I used google as you suggested, and your name was all that came up! Now why don’t you move onto UFOs or something more interesting than your boring old Evil Big Oil Conspiracy.
Nah, I’d rather stick around here just so I can pick your ass – because you’re too damn lazy to do it your own self.
Sheila, MadScientist is spouting nonsense about how safe fracking fluid is … there’s a reason that a Halliburton executive publicly drank a glass of their new fracking fluid, CleanStim, which is currently in field trials, rather than the stuff they have been using all along. But you are an embarrassment to the environmental and skeptical communities with your wild attacks and hearsay assertions and your nonsense about “N2″ which, if it isn’t the inert gas that makes up 90% of our atmosphere, you have failed to identify.
Hi Marcel, you can do your own research on N2, and I can guarantee that’s what they are using. So how come they aren’t just using N? I have no answer for that.
N2 is nitrogen, an inert and non-toxic gas, most of the air you breath is N2. N2 is not an ingredient in fracking fluid, however it is sometimes used instead of fracking fluids when it is pumped underground to break up the rock. It is not a secret mystery chemical. You could find this all out for yourself using Google in about two minutes. Your friend (if he exists), the one who can’t take a camera-phone to work, is mistaken about what the N2 is and what it is for.
I misread the title at first, and thought it was a followup experiment to Boobquake.
I’m glad I’m not the only one! haha
Yes, Brian, just what are you hiding?
Dear Brian – you make an omission and people pull your funding? You must feel like a politician. Forget the accusations of your being a corporate shill – the real interest group appears to be oversensitive listeners with itchy Paypal trigger fingers. I hope that, when Skeptoid starts bringing in the real money, this group will be sufficiently small for you to weather the financial effects of any ruffled feathers.
As for your remaining, non-paying listeners, I hope that more of them realise that good work deserves remuneration.
He didn’t say that people pulled their funding because of an omission, he just said people pulled their funding within 24 hours after the episode came out.
Ha ha ha – it’s true!
I think it’s pretty funny – does that mean his paying listeners are skeptics who subscribe to Big Oil Conspiracy?
It wasn’t that long ago that big oil did get away with anything they wanted to. Even though there are laws in place that doesn’t stop them from doing a lot of cya (cover your ass). A lot goes on in the oilpatch that would make a skeptics hair stand up on end.
There was a whole day devoted to the Marcellus Shale and fracking at the last GSA regional meeting I attended. It’s a big deal, but no one was suggesting it was causing good-sized earthquakes. It just doesn’t make sense with the geology.
Okay, you finally got me Brian. I’ve resisted your entreaties for monetary help for years. I’m going to toss you a bone for all the Skeptoid deliciousness you’ve been bringing us. And cover more geological subjects while you’re at it.
As (I think) the second person who commented asking about the earthquake thing, I feel I should comment. You had mentioned that some people believed earthquakes were caused by fracking, but left it there. Your response to my comment and others referring us to that article was enough, but I do appreciate you doing this follow-up. At the time, I had felt like I was missing out on good skeptical entertainment without that bit of closure, but of course, having the actual science is even better. :)
You may have blocked my twitter account (@dkreidler) over a pointless kerfuffle, but this is why I still follow you and have a 5-star review up on iTunes: You do an amazing job of exploring all the aspects of a topic, and then exploring which make the most sense. I’ve always *assumed* fracking is bad, since it falls into the same basic categories as drilling, mining, etc. However, it doesn’t take place anywhere near me, so I’ve never had to actually look at the details and processes. Knowing more of the realities, versus whatever rumors and misinformation percolate through pop culture, is just plain empowering. Thanks, Brian!
Hopefully he’ll consider unblocking you. It’s so easy to get into kerfluffles with allies on the internet.
While I doubt Brian and I would see eye-to-eye on many political issues, I’ve found we have lots of agreement when it comes to Skeptoid topics. Kudos to Brian for tackling this topic even though it’s so intertwined with politics and opinion.
FWIW: My grandmother’s well water had so much methane in it it would almost knock you over when you turned on the tap. She lives in central Nebraska and there no active fracking sights within hundreds of miles of her home. No correlation = causation there.
But was there seismic activity? Because I’ve seen the same thing and it didn’t happen until after seismic crews crossed their land.
Old Muley: that sounds like a fallacy of denial of the antecedent. Methane in well water being sometimes caused by something other than fracking has no bearing on whether fracking causes methane in well water.
Perhaps Sheila could obstain from eating anything containing components of fracking fluid. That might be interesting. First, we probably have to explain what N2 is and what those other nasty chemicals are. Just because something has a letter and number does not make it evil.
Coming from Sheri who is on anti-depressants and all kinds of over the counter and under the counter drugs? No you don’t have to explain anything. You’re just saying that because you had to look it up. Madscientist offered to drink frac fluid and now he won’t, what a chickenshit.
“Coming from Sheri who …”
Textbook ad hominem fallacy.
Perhaps no one needs to explain to you what N@ is, but you do need to explain why it’s a problem or why you think, apparently, that it’s toxic.
Make that N2, not N@.
Well why don’t you drink it and find out for yourself?
Are you talking about drinking N2? Well you breathe it everyday or else you would die. I plan on breathing some in right now. Drinking it, now there’s a problem…. liquid nitrogen will probably kill you if you drank it, it’s really cold. Don’t drink liquid nitrogen. As for fracking fluid, well, looking at what’s in it I don’t think it would kill you, but hell I don’t even like drinking the city water where I am. Not because it won’t kill me, but I find it gives me gut rot. Crayola Crayons are non-toxic too but I shouldn’t have to eat one to prove it’s non toxic.
While a bit tangential to the subject, but interesting nonetheless, While producing American Dragster on ESPN, we were working on an episode that discussed and demonstrated the great power and energy created by the Nitro “top” Fuel dragsters during a competition drag race. Because of their huge nitromethane powered engines, they can propel a dragster past 330 MPH in 1/4 mile. I was there trackside on several world-record runs following Tony Schumacher for our show. We had heard that these engines can produce up to a 3.9 level earthquake on the richter scale at launch. When we pressed the sanctioning body, NHRA for accurate stats and more background to the claim, they told us to leave that little factoid out of the show. The reason given: If a serious earthquake had occurred in the Southern California area coinciding with a NHRA Top-Fuel event, their legal staff thought that they might be sued for inciting an earthquake with the racing! True Story.
Thank you Ryan for bringing this to our attention. Funny how so much gets “left out”. It’s all about CYA in all industries.
Whoosh!!!!
Sheila, drag racing does not cause earthquakes, even if it can cause measurable Richter readings. In this case, the “industry” asked that the item be left out because ignorant people might make a false connection, like all those folks who thought that Proctor & Gamble’s logo was satanic or who thought that “niggardly” is racist.
No Marcel, they left that part out to cover their asses and reduce their liability insurance payout if a quake happened to occur at the same time.
Marcel read the fine print on any insurance policy. You are not allowed to say that it was your fault and take responsibility for any wrongdoing.
I can’t see fracking making earthquakes. But when the dug the Panama canal they had local earthquakes from the land swelling up from the remove of the top layers. What’s happening as the ice melts? It would not be in the right places would it? Also the earth wobbles. The wobble has gotten worse. It’s said the only thing that could make that is water impoundment away from the equator to the top. Couuld that make new stresses and make quakes?
I’ll just leave this here.
http://www.ewg.org/analysis/usgs-recent-earthquakes-almost-certainly-manmade
Federal Scientists Link Oil and Gas Fracking to Earthquakes in U.S.
A new federal study has found the drilling practice known as fracking can trigger earthquakes. The U.S. Geological Survey found that oil and gas operations caused the majority, if not all, earthquakes in certain areas of New Mexico and Colorado between 2001 and 2011. The report’s co-author, U.S. Geological Survey scientist Justin Rubinstein, called fracking “a societal risk [we] need to be considering.”
************************************
This is one more case where Brian *believes* something he knows nothing about and “chooses science” to believe because that’s the safe side. This is a clear indicator of pseudo-skeptisism.
Interesting, even humorous conversation. Non-suckup, can you provide the name of the report and/or where it was published, please? All of this banter makes me long for a reputable source from which I may draw a logical, even appropriate conclusion. Much thanks –
Oh, never mind non-suckup; I just watched Amy Goodman on DemocracyNow give the headline about the report, and since I listen to KFPA as often as possible, I am not skeptical about its validity. Now then, I’m off to locate the actual report so I can make sure I havn’t been unduely influenced by the skepticblog conversation or any bias DemNow may have regarding fracking. Tootles : )
It never occurred to me to type unbiased into a search before. I appreciate an opinion that is not one sided. thanks for the good work. jen
I completed my PhD thesis at the Massachusetts Institute of Technology (MIT) in 1999 on the subject of microearthquakes associated with hydraulic fracturing at petroleum and geothermal reservoirs (a link to the thesis can be found here http://dspace.mit.edu/handle/1721.1/9679).
Here are a few of my thoughts:
Hydraulic Fracturing, by definition, causes earthquakes because fracturing of previously unfractured rock (the intent of fracking) nucleates a new rupture face or reactivates a prexisting weakness in the rock being fractured so that new porosity and permeability can be created allowing fluids to flow through the formation being fractured. That being said, however, the earthquakes produced are generally small, meanining that they would be determined to be categorized as “microearthquakes” which are less than Magnitude 2.5 on the Richter Scale and many are much, much smaller than that. Some larger earthquakes near hydraulic fracture works and their subsequent operations of either fluid injection or extraction have been documented. The process of hydraulic fracture and its relationship with the spatial and temporal distribution of “induced” microearthquakes has been the focus of intensive research for several decades and it remains so as the subject is extremely complex, socially and environmentally important and academically fascinating. There are many organizations working on understanding this compex relationship, both in the US and abroad, including EPA, US national Laboratories (Los Alamos, Scandia, Lawrence Livermore), nearly all of the petroleum and energy companies, and many of the leading research Universities in the world including (but not limited to) MIT, Tohoku University, Tohoku, Japan, Harvard University, Stanford University, etc. Many many reasearch papers have been published on the subject as well in Primary Peer-Reviewed Journals, Secondary Sources such as subject specific conference proceedings and University theses. For those who may be interested I recommend reviewing these available references, but many are not for the faint of heart as they can be quite mathematically challenging. While my thesis may or may not be of specific interest, I did include a historical review of induced seismicity associated with energy related operations at geothermal reservoirs and other historically interesting sites and that chaper (ch 1 in the above cited volume) is pretty layman friendly for reading purposes. I have also included a very extensive reference list that was current at the time of publication (1999). Happy reading!
Thanks Shirley,It’s always nice to hear from someone who has studied deeply on a complex subject. What you have stated seems to agree with what I have heard from other reliable sources as well.
New study in Science just came out, confirming that fracking and wastewater disposal cause earthquakes: http://www.sciencemag.org/content/341/6142/1225942
http://www.telegraph.co.uk/finance/newsbysector/energy/8864669/Cuadrilla-admits-drilling-caused-Blackpool-earthquakes.html