Do I Think That Fracking Causes Earthquakes?

June 7, 2014

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

Note: My analysis presented here is based on what was known about this issue at the time that I wrote this (June 2014). I don’t think the essence of this analysis has changed (yet?), but as more earthquakes occur near fracking sites the details of the issue are evolving.

These days, I can hardly go anywhere without being asked: “So, tell me, does fracking cause earthquakes?” Not wanting to get into a complex scientific and political argument on the spot (especially in social situations), I generally try to change the subject.

But, I guess there’s no avoiding it. Being a seismologist, I do have a responsibility to answer. So, here’s my take on it.

Short and simple answer: Yes.
Longer answer: But, it’s complicated…

“Hydraulic fracturing,” also known as “fracking”, is a method of injecting fluid into the ground to fracture rock for extracting natural gas. In the process, fracking creates many very small earthquakes. These small earthquakes are generally (so far?) too small to be felt or to cause structural damage or injury. However, part of a fracking operation involves the use of high volumes of water to release natural gas from dense rock, and disposing of the associated wastewater involves injecting it into deep rock formations. That wastewater injection can “induce” or “trigger” earthquakes in faults that have been dormant (and might have otherwise remained dormant) for a very long time. These wastewater-injection induced earthquakes are not necessarily so small, and can be damaging. And that is (so far?) where the fracking/earthquake problems and controversies lie.

Here’s my summary of the story:

  • There are well-documented cases of earthquakes clearly associated in time and space with fracking operations. But it’s not really the fracking itself that triggers the earthquakes that are likely to be damaging, it’s the disposal of fluids via injection of highly pressurized wastewater into faults that more likely tends to induce the larger, potentially damaging earthquakes.
  • Most earthquakes associated with fracking operations have been smaller than magnitude 3. But a few larger and damaging earthquakes are suspected of having been induced by the injection of wastewater from natural gas (and also oil production) operations. On the seismogram shown below, you can see the Weston Observatory/BC-ESP recording of a magnitude 5.6 earthquake that occurred in Oklahoma on November 6, 2011 and is suspected of having been induced by injection of wastewater from oil extraction. Although that earthquake has not been directly linked to fracking, the injection of wastewater from oil extraction is essentially the same process as what occurs in fracking operations.
  • There is a well-known theoretical explanation of why injection of highly pressurized wastewater into faults could induce earthquakes. The increased pore pressure along the fault effectively lubricates the fault, causing it to release stress that might have been building up for many years, but might not have slipped without the excess pore pressure.
  • Out of hundreds of thousands of fracking operations, and the associated disposal of wastewater, so far only a few have been clearly identified as being related to induced earthquakes of any significant size. The vast majority of operations have not, so the probability of a given fracking operation inducing damaging earthquakes is probably very low (much less than 0.1%).
  • Just how large and damaging a fracking/wastewater injection-related induced earthquake could be remains unknown. Although such earthquakes are generally smaller than magnitude 3, and the largest earthquakes claimed to be fracking-related are less than magnitude 6, even larger future earthquakes can not be ruled out. More research on this topic will be necessary to answer the question of just how big future wastewater injection-related induced earthquakes might ever be.
  • There are many other environmental issues related to fracking, such as heavy truck traffic and contamination of nearby well water used by local communities for drinking water. These are important issues to consider regardless of the question of whether or not fracking operations induce earthquakes.

Bottom line for me: These kinds of things are complicated. I think a more relevant question than “Does fracking cause earthquakes?” is: Given that wastewater injection procedures associated with fracking operations can induce earthquakes big enough to cause damage in some (small?) percentage of cases (and that there are other environmental hazards associated with fracking), what should we do about it? Fracking provides new sources of natural gas that could enhance our ability to generate electricity, heat homes, and provide fuel for transportation. Given the uncertainties, how do we to find the right balance to make informed decisions about the extent to which the risks associated with fracking, or with any other process for finding new sources of energy, are worth the benefits?

This is the challenge for all of us as citizens of planet Earth.


Weston Observatory/BC-ESP seismogram of magnitude 5.6 earthquake that occurred in Oklahoma on November 6, 2011. This earthquake is likely related to injection of highly pressurized wastewater (from oil extraction operations) into wells. It was big enough to cause injuries and damage more than a dozen homes. (Click on seismogram to enlarge.)

Further Reading:

For an excellent, more complete, analysis of the situation, see the USGS Science Feature article Man-Made Earthquakes Update, and follow the links in it.

Weston Observatory Records Magnitude 7.0 Earthquake in Japan on April 15, 2016

April 15, 2016

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

On a April 15, 2016, a magnitude 7.0 earthquake that occurred on the Kyushu Island of Japan, was recorded by Weston Observatory (see seismogram below). The strong signal at the bottom few hours of the seismogram is the Japan quake. The other strong signals are other earthquakes that also occurred on the same day. The signal at the top is a magnitude 6.4 earthquake in Vanuatu, and the smaller signal about an hour before the Japan quake is a magnitude 6.1 earthquake that occurred in Guatemala.


Today’s magnitude 7.0 Japan quake occurred very near a magnitude 6.2 quake that occurred two days earlier. There is, of course, the likelihood of strong aftershocks of today’s main shock, but there is no way of knowing whether or not the occurrence of these two events would lead to any more large earthquakes in this area.

A tsunami warning was initially issued for this earthquake, but the warning was later lifted.

Check back here for updates on this earthquake.

Additional information about this earthquake can be found on the U.S. Geological Survey earthquake monitoring web site.


Students Use BC Library Seismograph to Monitor Earthquakes and Storms, and the Test Prototype of Seismographs in Public Places

February 10, 2016

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

Weston Observatory and the Boston College Lynch School of Education recently installed a seismograph in the BC O’Neill Library (​first floor study area). This seismograph display is a prototype of our new version of seismographs operating in public places.

Figure 1: Seismograph display in the Boston College O’Neill Library.

Our first recorded earthquake at this site occurred beneath the Kamchatka Peninsula of Russia​. Because the epicentral area is sparsely populated and the earthquake was 100 miles deep, this earthquake is not likely to have caused serious damage or casualties.

Figure 2: Earthquake recorded by the BC O’Neill Library seismograph.

On January 23-25, we recorded a snowstorm in the Boston area, as well as a magnitude 7.1 earthquake that occurred in Alaska.

Figure 3: Snowstorm and Alaska earthquake recorded by the BC O’Neill Library seismograph.


Seismic Monitoring of North Korea Nuclear Tests

January 7, 2016

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

People have been asking why Weston Observatory didn’t record the recent “seismic event” in North Korea.

It was much too small (magnitude 5.1) for us to see it this far away at our New England Seismic Network (or BC-ESP) stations. For us to see a seismic event at that distance, it would probably have to be about a magnitude 6.0 or higher. However, Weston Observatory seismologists also track recordings at seismic stations operated by collaborating observatories that are closer to North Korea.

Here are the seismograms at Weston, MA where it wasn’t recorded and at the IRIS/USGS station at Mudanjiang, China (MDJ) where it was recorded very well. This figure shows the MDJ seismogram and also the “spectrogram” (multi-colored plot, calculated by Dr. Jay Pulli, Visiting Scholar at Weston Observatory).

NKorea_010616_Fig1(Click to enlarge.)
In this next figure (from IRIS and USGS) you can see the 1/6/2016 event seismogram, superposed on three other seismograms of previous North Korea nuclear tests. The seismograms are so similar that it is hard to distinguish the 2016 event (shown in red). This was one of the first clues that the event was probably a North Korea nuclear test. The biggest difference is just the relative sizes of the nuclear tests.
NKorea_010616_Fig2(Click to enlarge.)
​Seismologists will be studying these, and other, seismograms of North Korea nuclear tests for forensic analysis of details of the nature of the 1/6/2016 event.

Spectrograms: Visualizing How the Frequency of Seismic Waves Varies With Time

December 15, 2015

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences, Boston College

These (very cool, and beautiful, I think) graphics are “spectrograms” of some of our recordings of the magnitude 4.7 earthquake that recently occurred in Oklahoma.

The seismograph in Texas is operated by Kristi Rasmusson Fink, and the seismographs in MA are operated by Weston Observatory. The data processing was done by Jay Pulli.

A spectrogram is a particular way of visualizing the vibrations present in a seismogram. It shows how the frequency of the motion varies over time, and how different frequencies of vibration appear at different times in the record. Yellow colors represent stronger signals, and blue colors represent weaker signals.


More (Fracking Related?) Oklahoma Quaking…

November 30, 2015

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences, Boston College

Just this past week alone, there have been 32 earthquakes detected in Oklahoma (magnitude 2.0 to 4.7). Our seismograms and “spectrograms” of today’s magnitude 4.7 quake are shown below.

(The seismograph in Texas is operated by Kristi Fink and the seismographs in MA are operated by Weston Observatory. The data processing was done by Jay Pulli.)


Students Make Their Own Earthquake!

May 22, 2015


Clear and Simple Illustration of Mechanism to Explain Earthquakes in the Central and Eastern United States

June 6, 2014

This is a clear and simple illustration (adapted from the South Carolina Earthquake Education and Preparedness Program) of the commonly accepted “ancient zones of weakness” model for the cause of earthquakes in the Central and Eastern United States (and other “intraplate” regions far from plate boundaries). According to this model, preexisting faults and/or other geological features formed during ancient geological episodes persist in the intraplate crust, and, by way of analogy with plate boundary seismicity, earthquakes occur when the present-day stress is released along these zones of weakness.

IP_Quakes_Logs_AdaptedAlso see:

Why Does the Earth Quake in New England? and South Carolina Earthquake Education and Preparedness Program

Please Donate to Support Our Work

April 27, 2014

If you benefit from these blog posts and feel inspired to contribute to our work, please visit this page and make a donation.

At Weston Observatory, we’ve been busy this year envisioning and building an earthquake observatory for the 21st century, and we are now embarking on a fundraising effort to support our vision.

This year’s fundraising theme is education and public outreach. Funds contributed this year will primarily go towards bringing earthquake and related science into schools and public libraries, supporting our monthly public colloquium for adult learners, and of course towards maintaining this blog.

If you feel inspired to make a contribution, please click here to go to our donations page.

Thank you for any amount, small or large.


Broken Garage Door Springs, Earthquake Prediction, and Earthquake Triggering

March 6, 2014

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences
Boston College

(Originally Posted: April 27, 2012)

A few days ago, one of the huge springs on our garage door opener broke, with quite a big KABOOM!

It seems to me that this is a perfect example of the problem of earthquake prediction. Here’s what I see as the connection:

In the morning, the garage door repair guy (who happened to be there fixing something else) looked up at the spring and said, “That deformed spot in the spring is ‘metal fatigue’ – it might break in 5 minutes, or it might break in 10 or 20 years.” Then, two hours later, it broke! (Perhaps he disturbed the internal stress field while he was fixing something else?)

This seems to be a perfect analog of the Elastic Rebound Theory of earthquakes, and the phenomenon of Earthquake Triggering!

It also explains why we knew that an earthquake was lurking in Haiti, but we couldn’t tell when it would occur: The tectonic stresses were ready to be released in an earthquake, but nobody could tell if the earthquake would occur in minutes, in years, in decades, or in centuries…


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