Manmade earthquakes around the world:

This article describes several known and possible causes of man-made earthquakes around the world and provides links to and citations of expert sources on both manmade earthquakes and the unclamping effects of pressure changes in the earth or in rock formations that may explain an increase in earthquakes in some areas as well as certain severe earthquakes that have occurred around the world.

For building professionals and building owners/occupants, the apparent increase in earthquakes traced to human activity must be considered when evaluating both existing building damage and in predicting future losses or safety hazards.

The page top illustration is a USGS map showing the epicenter of a recent earthquake near Oklahoma City in the U.S. - an earthquake that may have been triggered by the cumulative effects of pressure-well disposal of oil drilling wastewater, though other causes may also be considered.

Manmade Earthquake Damage Sources: mining, oil or gas extraction & hydraulic fracturing or "fracking" activities can lead to earthquakes

In diagnosing earthquake type damage to buildings and their structures or foundations, note that even in areas that are not considered earthquake zones earthquakes may occur and may be traced to human activities.

Photo at left: building damage in Los Angeles examined by the author [DF] following California's Northridge Earthquake of 1994. This building collapse was not due to a man-made earthquake, but ...

Significant earthquakes are increasingly occurring within the continental interior of the United States, including five of moment magnitude (Mw) ≥ 5.0 in 2011 alone. - Keranen et als (2013) [27]

When a stress fracture is unclamped, areas of rock formation may move or "slip" past one another causing earthquakes of varying magnitude. [12] Ross Stein at the USGS offers this crisp explanation of the effects of unclamping and its relationship to earthquakes: [13][14][15]

An earthquake alters the shear and normal stress on surrounding faults. New evidence strengthens the hypothesis that such small, sudden stress changes cause large changes in seismicity rate. Rates climb where the stress increases (aftershocks) and fall where the stress drops.

Both increases and decreases in seismicity rate are followed by a time-dependent recovery. When stress change is translated into probability change, seismic hazard is seen to be strongly influenced by earthquake interaction. - Ross Stein (1999) [13] 

King (2001) reported similarly on "fault interaction by elastic stress changes" [18] Drilling and mining activities are also traced to a different type of earth movement: sinkhole formation in many areas of the world.

Details and examples are at SINKHOLES, WARNING SIGNS. But in addition, even if sinkholes are not appearing over or close to drilling and mining sites, oil drilling and in particular the disposal of oil-drilling wastewater by forced injection into underground wells may cause earthquakes of sufficient magnitude to damage buildings by causing changes in underground rock formation pressures, a process referred to as unclamping of pre-existing stress-faults.

Manmade Earthquakes in Oklahoma and Other Parts of the United States

USGS scientists have found that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells. Much of this wastewater is a byproduct of oil and gas production and is routinely disposed of by injection into wells specifically designed and approved for this purpose.

... It has long been understood that earthquakes can be induced by impoundment of water in reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations. - USGS (2013) [26]

In December 2013 The New York Times reported a significant increase in the frequency of earthquakes in and around Oklahoma city, an area with a long history of extensive oil drilling and exploration.

The Times explained that the area, not previously known to be earthquake prone, had historically experienced about 50 earth tremors annually, almost all "minor". But in 2013 the area experienced more than 2600 earthquakes including 87 in the second week of December of 2013. In addition to the 520% increase in earthquake frequency in the past year, in 2011 the area suffered a 5.6 magnitude earthquake, the largest ever recorded in Oklahoma. [12]

The Times article reported that disposal wells pose the greatest risk of causing these unclamping type earthquakes and that the cumulative effects of years of disposal of oil drilling wastewater into pressure fed wells may have reached some cumulative tipping point.

The article pointed out that there could be other explanations as well, and Toda and Stein reported on the cumulative effects of earthquakes as a force that "untoggles" earth movement.[19] And Hayes, U.S. Department of Interior observed in 2012

USGS’s studies do not suggest that hydraulic fracturing, commonly known as “fracking,” causes the increased rate of earthquakes. USGS’s scientists have found, however, that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells. [28]

Catalog of Recent Manmade Earthquakes Around the World & Unclamping Effects

The New York Times reporter, Henry Fountain, included a mini catalog of locations where injection wells or other human activities had the effect of unclamping old faults and leading to earthquakes that we have expanded a bit from other sources.

• Australia, 1989 Earthquake: cumulative effect of removal of billions of tons of coal
• Canada: British Columbia, possible effects of fracking (hydraulic fracturing by injection of high pressure liquid into shale rock to obtain oil or gas*)
• China, Sichuan Province, 2008 Earthquake: weight of water behind a new dam [16]
• England: possible effects of fracking *
• Italy: "... If previous ruptures unclamp the fault planes of subsequent earthquakes, fluid flow can play a dominant role in promoting earthquakes during the seismic sequence." (the 1997 Umbria / March earthquake) [21]
• Netherlands: In March 2013 The New York Times reported on new earthquakes occurring at Loppersum in the Netherlands. Tremors have been recorded at a magnitude of 3.4 on the Richter scale. The Times reporter explained that after more than fifty years of natural gas extraction in the area, recent earthquakes have become more common. Quoting from the Times article: Chief Seinen, a spokesman for the gas consortium known as NAM, said the extraction had created at least 1,800 faults in the region's subsoil. 'These faults are seen as a mechanism to induce earthquake.' he said. [8]
• New Zealand: deliberate manmade earthquake at Christchurch, testing in 2012 [25]
• Japan, 2011 Tohoku earthquake: time-dependent stress transfer and toggling effects of earthquakes [23]
• Switzerland: geothermal projects
• United States:
  • California: geothermal projects, mining projects (the 1992 Landers earthquake & the 1999Hector Mine earthquake) [17][22]
  • California: Simpson & Reasenberg reported on earthquake-induced static stress changes on central California fault lines [20]
  • Oklahoma: possible effects of oil well wastewater disposal into wells [27]
  • Oklahoma: possible effects of fracking *(hydraulic fracturing by injection of high pressure liquid into shale rock to obtain oil or gas)
  • Texas: use of water flooding to improve old oil well yield;

* The December 2013 New York Times article noted that fracking-related earthquakes occurred only over short time periods, unlike other earthquakes traced to or suspected as the cause of manmade earthquakes. [12]

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: How to distinguish earthquake damage from other structural movement

Is there anyway to prove earthquake damage to a foundation? I have a single story ranch house built in the 1930’s that has recently been subjected to a mild earthquake in 2009 and 2011 (Midwest) both of which I felt the house shaking and was awaken from a sound sleep.

I have glass block windows that have started to splinter in one of the sections of my basement. Started first sometime after March 2011 when I notice the blocks were cracked.

A couple of weeks later I found glass fragments splintering from blocks. Been watching it periodically then forgot until yesterday I found several larger pieces of glass block…corner pieces on two of them. The mortar that holds the blocks in window area show cracking as well. This would indicate to me that there is still ongoing stress to my frame house which is causing continual splintering from the glass blocks.

I contacted a structural engineer who said it was not possible by looking at it to tell whether it was earthquake damage or not. He indicated soil testing would have to be done which would be very expensive.

I am concerned that my home or at least parts of it will collapse. I have contacted my insurance agent but they do not provide any services of which to tell if it is earthquake related or not.

If you have any referrals or helpful information, I would appreciate it. - Thank you,- B.O. in Missouri

Reply: Expert, experienced inspectors should be able to form a reasonably confident opinion about building damage, extent, and cause

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with the structure, its history, probable cause, and extent of impact on the building and its safety.

That said,

I'm in no position by mere email to argue with your engineer, but having inspected a very large number of earthquake damaged buildings (while serving the Red Cross) it is my OPINION that an inspector, contractor, home inspector, or engineer who has familiarity with earthquake damage in general as well as with specific earthquake activity in a particular area can recognize the presence of damage to the building structure and form an opinion about its general safety.

If inspected by an experienced diagnostician, typical causes of building structural movement can almost always be traced to a probable cause. In all cases of building foundation or other structural damage, understanding the cause of the damage is an essential part in planning for the necessary repairs.

For example, lateral or horizontal "shaking" by an earthquake is likely to damage all sides of a building while differential settlement due to soil problems tends to cause focused cracking, bending, leaning etc. If the cause of foundation damage is inadequate footings the repair requirements may be quite different from earthquake damage.

I am unclear why soil testing is a high priority step in evaluating the building;

The first order of priority, which should not be delayed, is an inspection of the property for safety and safe occupancy. Unless your property actually has no significant damage of any kind (regardless of origin), that inspection needs to be performed for your own safety regardless of arguments about the root cause.

Watch out: - some safety defects that may be present following an earthquake as well as following other structural movements or damage can be subtle such as gas leaks and unsafe electrical wiring - even if the visible structural damage is minimal. At Northridge following the LA earthquake some buildings were very extensively damaged by the side to side movement of the earth during that event. But other buildings looked just about perfect, still sitting square on their foundations. Yet some of those "perfect-looking" structures were unsafe due to gas leaks that risked (and in some cases occurred) explosions and fires caused when subtle building movements damaged the utility lines.

Question: our newly built townhouse vibrates and shudders and we hear banging

Just moved in to a new build town house which vibrates constantly and suffers with shuddering (top/3rd floor more noticeable with windows also shaking). On ground floor can sometimes hear banging, like someone has jumped or dropped heavy object from above. On a main road but this does not always happen when heavy vehicle drives past. Also suffering noise from pipes/ventilation outlets. - Lesley Anne 12/29/2011

Reply:

Lesley:

If the building movement and noises you describe were due to an earthquake or ongoing temblers or tremors, you could quickly confirm that condition with your local emergency services departments and building department, or perhaps even neighbors, as other buildings would be experiencing symptoms as well.

If that is not the case, then what you describe sounds specific to your individual building. Because some building movements, vibrations, and sounds can be symptoms of a pending catastrophic collapse, it makes sense to ask for expert advice promptly. An expert will listen to your concerns and will make his/her own thorough inspection of the structure both outdoors and inside, looking for

Indications of actual building movement and related damage, such as cracks, separation of framing, sticking windows or doors, floors or ceilings out of level, walls out of plumb.

Indications of foundation movement or damage such as cracks, leans, bulges, bows.

The purpose of the initial assessment of building condition will focus on the discovery of signs of an immediate life safety hazard. If that sort of hazard is comfortably ruled out, what remains may be construction methods and materials issues to review with the building owner, contractor, or an independent professional structural or civil engineer who is familiar with the type of construction used for your building.

Keep us posted, what you learn may assist other readers.

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Continue reading at SINKHOLES & SUBSIDENCES or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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