I have two papers on induced earthquake.

Fracking can cause earthquakes surely.

One more publication about induced earthquake.

Thank you. Your answer was very clear. Do you think fracking can cause stronger earthquakes than magnitude 5 ?

Thank you Martin for your useful answer.

The answer depends on what you mean by `cause`. Fracking won't build up sufficient pressure to make any significantly strong earthquake happen in an otherwise unstressed region. However, as also the mentioned literature suggests, fracking can trigger an earthquake, i.e., set off ruptures under previously existing tensions. I would guess, however, that such earthquakes should happen sooner or later anyway, even if no human activity whatsoever contributed to their onset. I might even be that those events would be stronger if nature had more time to build up further tension. On the other hand, it is also conceivable that a change in the regional stress field might reduce these tensions before an earthquake could actually happen.

Stimulation through "fracking" would not be inherently responsible for an earthquake unless the stress of an area was near the point of fracturing naturally and the frac supplied the incremental energy and lubrication for failure to occur. Stimulation through the utilization of fracturing techniques have been taking place for over fifty years and I know of no study that has linked active earthquake activity associated with production of hydrocarbons. Injection of fluids into the subsurface has been linked to earthquake activity where the local geology has indications of pre-existing faults. The fluids in this latter case supply lubrication but do not create the conditions for an earthquake to occur.

No, it doesn't cause large earthquakes. One of the least appreciated points in the physics of earthquake is that the energy scales with the size of the fault. Because large earthquakes require large faults (approx. 33km for magnitude 6.5, >70km for magnitude 7.2, >200km for M8 and so on), there's practically no chance that localized hydraulic fracturing may destabilize large faults. I'm afraid that all the talk about rocks being near the point of failure as to fail by overloads and/or lubrication due to fracking and such, belong to the realm of para-science and show little familiarity with the seismogenetic process. Add the fact that seismicity results from a complex (critical) system with long-range interaction and long-term memory and you may conclude that earthquake triggering is so complex a process, as to leave room for para-scientific or misguided speculation about large "fracking-induced" earthquakes (including relevant literature). As William Brown pointed out above, fracking has been with us for over 50 years. Fracking is also used in very precisely monitored Enhanced Geothermal Systems. Analogous to fracking is the abstraction of water from geothermal reservoirs (reduces pore pressure). Not once there have been reports of sizeable earthquakes, including the Cerro Prietto field wich lies in the middle of the San Andreas fault. So, no large earthquakes are not probable. Small earthquakes (< 3.5) and microearthquakes are, nevertheless certain. This, however, is an altogether different process!

Hi.

Someone from USGS just gave a talk here on this topic (William Leith). He said that the earthquakes induced by fracking are actually not caused by the drilling biut by the water injection. But they are supposed to be small in magnitude.

We are talking about 2 different scales of energy. Earthquakes are generated after the accumulation of a huge amount of energy much bigger than any injection will provide. But the idea that fracking could trigger an accumulated stress already present: its a good idea that should be studied seriously or argued by observed facts. Untill know, I've found no paper arguing this, If somebody found any please post the link. Thanks.

Colorado is one area where studies have been conducted on the relationship between injection wells and earthquakes (particularly the Rock Mountain Arsenal deep well). I am posting two links which may be of interest. http://geosurvey.state.co.us/hazards/Earthquakes/Documents/ERC/DENVER%20AREA%20%20EARTHQUAKES%20AND%20ROCKY%20MTN%20ARSENAL%20DISPOSAL%20WELL-EVANS%201970-2ND%20FOLDER.pdf

http://www.aapg.org/explorer/2001/12dec/colo_quakes.cfm

In general, however, the evidence suggests that fracking and injection in sedimentary basins cause only micro-earthquakes which cannot be felt by humans.

Here some info from a UK perspective

From the British Geological Survey

http://earthquakes.bgs.ac.uk/research/earthquake_hazard_shale_gas.html

http://www.bgs.ac.uk/research/earthquakes/blackpoolMay2011.html

and from the BBC

http://www.bbc.co.uk/news/science-environment-22077230

http://www.bbc.co.uk/news/uk-england-lancashire-15550458

And the below article is no directly related but you may be interested in it

http://www.bbc.co.uk/news/science-environment-23271168

A brief summary concerning USGS, who has been covering the subject for quite some time now:

http://www.usgs.gov/blogs/features/usgs_top_story/man-made-earthquakes/?from=textlink

Attention: this assertion is dangerous :-"a change in the regional stress field might reduce these tension"- because it can also INCREASE tensions and ...

By performing fracking in active tectonic areas and/or affecting active faults, you could trigger induced earthquakes with a size as large as M5.5. The relevant question arises if a M 5.5 earthquake triggered by fracking could also trigger a large tectonic earthquake in the area by changing the stress field conditions (Coulomb stress transfer). Anyway, before fracking, start thinking!!, and study the area from a tectonic point of view, of course.

Spring rain on the Tokyo basin triggers earthquakes that are easily felt.

there are very few (if no) clear evidence of earthquake bigger then 3.6 M triggered by hydrofracturing techniques. Most of bigger induced earthquakes are associated to fluid injection for waste disposal or geothermal energy in area where the crust is already stressed (Ellsworth, Science volume 341, 2013). Said that it is well known since more then 50 years (e.g i suggest you to read the report of a beautiful experiment released to the US environmental protection agency and published in the US geological survey bulletin 1951, by Nicholson&Wesson) that under certain circumstances, the increased pore pressure resulting from fluid injection , whether for waste disposal (usually the most massive injections), secondary recovery, geothermal energy or in that specific case fracking techniques, can trigger small earthquakes and tremors.In most of the case it look like that the fault, although didn't record seismicity in historic times, was already in quasi critical state with stored energy then released by changes in stress or hydrogeological conditions. Basically those experiment indicates that the crust can respond by failing in an earthquake due to human activities such as hydrogeological extraction, fluid disposal and activities associated to non conventional hydrocarbon extraction. In most of the case (not all but debate are still going on as indicated by the recent publication by groups of Zoback, Brodsky and Ellsworth in science and PNRS) the magnitude of the induced seismic event are partly due to the size of any applied stimulation but mainly determined by the strength of the rocks being already stressed. We are speaking about seismicity below the magnitude of 3.5. The extraction/injection experiments registered and investigated (both geothermal, waste disposal and fracking) suggest that the water injection or extraction stimulation are the main effects that take the ambient stress within rocks beyond the yield point of the rock. The majority of the case where reasonable induced earthquakes (bigger then magnitude 3) . has been measured suggest that fluid injection associated to huge waste disposal in tectonically stressed area is the most probable effect. As an example take what happened in the Lancashire near Blackpool . We know from historical description that Lancashire region has been affected in the 1835 by earthquake of presumably magnitude 4.4 and not much happened or has been recorded since then. Suddenly a series of microseismic events in between April and June 2004 were detected also by the local population. There is agreement between the scientific community that the hydrofracture process (fracking) carried out at Preese Hall (Lancashire) was the trigger of the sequence of minor seismics events near Blackpool on april -June 2011 (max magnitude 2.4). But in that case it is now clear that the state of stress which was released by these events was pre-existing and the hydraulic changes made in hydrofracturing were simply the perturbation which initiated the sequences of events. Similar sequences are reported in Holland (near the Groningen field, where most of the earthquake are induced by hydrocarbon/gas exploration) and in Oklahoma. In all these case the difficulty derive from the lack of precise stress, pore pressure and seismicity data (before the injection experiment) in area where exploration or fluid injection are in due course. Similar conclusions have been reported by Van der elst (science, vol 364,p164, 2013) looking at fluid injection site in the Middlewest of the States and by Ellsworth (science, vol 341, 2013, Injection induced Earthquakes) reporting an overview of the recent experiments analyzed.

http://www.newscientist.com/article/dn24069-fracking-operations-triggered-100-quakes-in-a-year.html#.UhTEChaATXB

contains link to paper* which indicates that the injection of water after extraction, rather than the fracking itself, may be the trigger for earthquakes

* "Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio"

http://onlinelibrary.wiley.com/doi/10.1002/jgrb.50247/abstract

I answered the following in relation to a similar question. I think it is relevant here too:

Answers have already been provided here that refer to the effect of groundwater extraction in southern Spain. Elsewhere, examples occur where water storage in dams or deep mining for gold causes earthquakes, for example in South Africa.

One of the emotive issues in this arena relates to fraccing, the practice of pressuring rocks at depth to initiate fractures which help productivity of gas and oil. I have been involved in exploration and production of oil and gas from these so-called “unconventional reservoirs”. In all the examples I have seen, target horizons are from 1000 to 3000 m deep whereas local aquifers are at 20 – 100 m depth. There is therefore 1-3 km of rock between the target area and local water-bearing aquifers.

Secondly, it is true that small earthquakes are triggered, and the detection of these microseismic events is an important tool in reservoir stimulation monitoring. By mapping microseismic events, a view is provided of the extent of the fracture network. With recent innovation, microseismic may be monitored with surface equipment, by using a wide array of passive seismic receivers. Commonly, however, microseismic is only detectable by deploying downhole receivers, in a specially-drilled parallel monitor well. This is an indication of the small scale of the seismicity involved. It is detected only by placing equipment at similar depths, or by deploying a wide array of surface equipment.

The resolution of these systems is up to 10 times greater than provided by publicly available resources such as the US Geological Survey. New surface-based systems allow monitoring of activity prior to reservoir stimulation, during and after. In the past, when detection relied on downhole equipment, it was not possible to compare pre-drilling activity.

How many strong earthquake? M =5,6,7? Every one seismologist knows about the problems with dam lakes and rising seismicity in time there. But this is a magnitude no more 4-4,5. And there are billion tones water on the surface, you know.

In fracking we operate with quite many quantities and...It will be no seismic problems, I think.

Naturally every cause is specific in geological structure - materials, folds. Maybe potential seismic energy only will decides...Not the human fracking work...

Theoretically if hydraulic fracturing is carried out in passive segments of active faults then hydraulic fracturing may allow release of stain in the form on small earthquakes.

Non-scientists often confuse the fact that earthquakes are located near hydrofracturing sites with the quakes being caused by the hydrofracturing process. As has been noted above, most often the quakes are caused by the disposal of hydrofracturing wastes by deep well injection. Deep well injection has long been known to have the potential for inducing earthquakes. The USGS just released its new report on induced seismicity.

There is direct correlation of hydrofracturing and seismic movements. Seismic movements can cause tremors leading to earthquake.

Dear Pier Paolo Poncia and colleagues: Your question acquires a great importance in these days in the province of Neuquén, Argentina, and it is of great relevance to get to better understand the relationships that exist between fracking and seismicity, such as the Pablo J. Pazos´ answers express.

Please, let me share this article: "Intraplate seismicity recorded by a local network in the Neuquen Basin, Argentina" by Sebastian Correa-Otto et al., JSAES 87 (2018).

Mario E. Sigismondi

In the case of the Neuquina basin, Argentina, a dramatically increase such as "intraplate seismicity" has occurred to the southeast of Sauzal Bonito, since November 2015 there began to be perceptible seismicity in the area of ​​the Neuquén basin until the last 4 months (Nov / Dec 2018, Feb / March, 2019).

Please, let me share my personal opinion about this particular case:

• The depth of focus of the last event at almost 16 km depth does not match the depth of the Vaca Muerta formation at 3 - 4 km
• The greatest fracking activity is not in Sauzal Bonito, it is in Anelo, 35 - 45 km at NE direction.
• The intraplate natural seismic activity is corroborated before the production or intensification of Vaca Muerta fracking.
• It is not really proven that fracking at the depths of the Vaca Muerta itself can have an influence on the natural seismicity
• it is necessary to have a seismographs network, to detect not only isolated events, but also the lower magnitude earthquakes that are not detected by stations in Chile.
• It also requires a more investigation of the geological fault involved, determining the speed of displacement in order to estimate its real seismic potential.
• It is also requires to crossplots the natural seismicity data with microseismicity data monitored in E&P wells.
• The damages produced in homes of Sauzal Beautiful are the product of the action of the strongest earthquakes and their subsequent replicas, it should be noted that the facilities are not ready due to their construction. So, we need a seismic zonification research to planning the home constructions.
• Neuquina basin has a large coverage of 3D seismic data, but exactly in the area of ​​hypocenters in Sauzal Bonito does not have 3D seismic, despite a regional coverage more than forty thousand square kilometers. I

I invite you to share your own experiences in other study cases.

Best wishes colleagues,

Mario

Following "Breakdown of the Gutenberg-Richter relation in layered media" GeoConvention 2014: FOCUS, by Eaton, 2014:

"For three widely separated hydraulic fracturing field examples, microearthquake magnitudes are not well represented by the classic Gutenberg-Richter relation that describes earthquake occurrence on active fault systems. A more satisfactory fit is obtained assuming that the magnitude distribution represents activation of stratabound fracture networks. The size distribution of microearthquakes induced by hydraulic fracturing in oil and gas development may thus reflect an intrinsic preferred scale length, which is fundamentally different from scaling of earthquake fault systems. Our model implies that statistical characteristics of fracture networks may be determined using observed microearthquake magnitude

distributions, with important ramifications for incorporation of microseismic observations in reservoir models."

Personally, I think that it depends on:

- Deep of the target to be fractured & seal efficiency

- type of the rock to be fracked, is is soft (Shale) or tight (eg: Tight sandstones...)

- Intensity of fracking (amount of solvent injected & Number of wells per sq/km)

- The place subject of hydraulic fracking ( in a calm or active tectonic setting, is there any master faults close by ?)