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Wastewater Injection Causes Oklahoma Earthquake Problem

OklahomaEQsBarGraphOklahoma has been the epicenter of a new environmental problem related to modern times: an increase in the number of earthquakes. Usually the state has 0 – 3 earthquakes per year above Magnitude 3.0, with the strongest being a M5.5 in 1952. In 2009, however, the number of M3.0+ earthquakes each year began increasing. In 2013 the Oklahoma Geological Survey registered 2 of them each week, and since then the rate has continued to increase. As of 4/21/15, the current rate was 2.5 per day! The trend is shown in the chart at right.

Then, in 2011, a Magnitude 5.6 earthquake struck east of Oklahoma City. That’s big enough to cause damage.

According to the Oklahoma Geological Survey, it is

very likely that the majority of recent earthquakes, particularly those in central and north-central Oklahoma, are triggered by the injection of produced water in disposal wells.

The primary suspected source of triggered seismicity is not from hydraulic fracturing, but from the injection/disposal of water associated with oil and gas production. Produced water is naturally occurring water within the Earth that is often high in salinity and co- exists with oil and gas in the subsurface. As the oil and gas is extracted/produced, so is the water. This water is then separated from the oil and gas and re-injected into disposal wells, often at greater depth from which it was produced. (OGS, 4/21/15)

Be sure to catch the distinction here: the problem they identify is not the fracking itself, but rather the water that comes out as the oil and gas are extracted. That water is contaminated, and they dispose of it by injecting it into disposal wells at high pressure. These wells are the suspected culprits.

Earthquake locations. Red = 2014, Green = 2013, Blue = 2012 and previous. Source: Peterson, et al, 2015, Figure 3A.

Earthquake locations. Red = 2014, Green = 2013, Blue = 2012 and previous. Source: Peterson, et al, 2015, Figure 3A.

The area of increased seismic activity stretches from central Oklahoma north into Kansas. It is not the only area experiencing such increased activity. A recent U.S. Geological Survey report identifies 17 areas that have. Five are in Colorado, one in New Mexico, five in Texas, one in Arkansas, one in Mississippi, and two in Ohio. But by far the largest ones are the two involving Oklahoma and Kansas. The map at right shows their locations.

To understand the map, a little background is needed. The USGS studies earthquakes primarily to understand earthquake risk. Their knowledge is used by building officials to determine how earthquake-proof buildings in a given region need to be, and by the insurance industry to understand risk. Earthquakes tend to come in clusters; when there is an earthquake, it results in aftershocks, and sometimes it sets off additional earthquakes nearby. It does not add much to the understanding of risk to say that once there has been an earthquake, others are likely to follow. Thus, the USGS keeps catalogs of earthquakes in two ways. One way is to list an initial earthquake, its aftershocks and its subsidiary quakes as a single cluster. These catalogs are called nondeclustered. I don’t know why they use this awkward double negative, but the point is to try to identify the risk of when a cluster will occur. The other way is to list all earthquakes as individual, separate events. These catalogs are called declustered.

The map at right combines data from both kinds of databases. The dots represent the epicenters of earthquakes of Magnitude 2.7 or larger. The blue dots represent earthquakes prior to 2012 using a declustered catalog. The green dots represent 2013 earthquakes from a nondeclustered catalog. And the red dots represent 2014 earthquakes from a nondeclustered catalog. In other words, the red and green represent single years, and in those years aftershocks and subsidiary quakes have been grouped as a single cluster with their initial earthquake. The blue dots represent all the years before 2012, and each aftershock and subsidiary quake is counted as a separate event. Obviously, the recent outbreak of earthquakes has been quite severe. The majority of these earthquakes have been small or moderate. However, there has been a trend towards increased magnitude, and a few of them have been sufficiently large to cause some property damage.

The kind of waste injection well identified as the culprit in the Oklahoma earthquake swam is permitted in Missouri, but it does not appear to be common. Missouri has little oil and gas extraction compared to some other states. We have not been identified as one of the regions experiencing a swarm of human-induced earthquakes. Our earthquakes center around the New Madrid Fault, a known area of seismic activity.


Oklahoma Geological Survey. 4/21/2015. Statement on Oklahoma Seismicity. http://wichita.ogs.ou.edu/documents/OGS_Statement-Earthquakes-4-21-15.pdf.

U.S. Geological Survey. 2015. Earthquakes in Oklahoma of M3+. http://earthquake.usgs.gov/earthquakes/states/oklahoma/images/OklahomaEQsBarGraph.png.

U.S. Geological survey. Oklahoma Earthquake History. Web page accessed 4/25/15. http://earthquake.usgs.gov/earthquakes/states/oklahoma/history.php.

Peterson, Mark, Charles Mueller, Morgan Moschetti, Susan Hoover, Justin Rubinstein, Andrea Llenos, Andrew Michael, William Ellsworth, Arthur McGarr, Austin Holland, and John Anderson. 2015. Incorporating Induced Seismicity in the 2014 United States National Seismic Hazard Model – Results of 2014 Workshop and Sensitivity Studies. USGS Open-file Report 2015-1070. http://pubs.usgs.gov/of/2015/1070.

Missouri Continues to Experience Increase in Earthquakes

Last May I reported on the startling increase in the number of earthquakes in the Central United States in places not known for earthquake activity. Oklahoma and Arkansas had seen an increase of 16X in moderate earthquakes. I asked whether Missouri had also experienced an increase in earthquakes. It had, although nothing like the outbreaks in Arkansas and Oklahoma. This post updates that information. In the next post, I’ll look at some information identifying earthquake swarms that have been induced by human activities.

MO Earthquake Frequency ChartAt right, I’ve updated a couple of graphics from the post last May. The first is a frequency chart of earthquakes above Magnitude 2.0 in a square region that approximates Missouri. (The USGS data tool does not permit selection of a state. The area I used this time is close, but not precisely the same as the one from 2014. The precise area is given in the Source List below.)

(Click on chart for larger view.)

The chart shows that Missouri had a small, temporary increase in earthquakes in the early 1990s. In 2008, however, the number of earthquakes began increasing, and it skyrocketed in 2013 and 2014. The average number of earthquakes for 1980-2012 was 8.3, while the average number for 2013-2014 was 47, an increase of 464%.

Most of them were small earthquakes. The largest was a Magnitude 4.7, which occurred in 1990. In 2013-14, the largest was a Magnitude 3.3, which occurred in Tennessee. Such an earthquake may be felt, but it rarely causes damage.

Missouri Earthquake MapThe second graphic at right is a map showing where earthquakes have occurred. The map shows earthquakes from 2008-2014, with a magnitude above 2.0, that occurred within the same geographical limits used above. Missouri’s earthquakes center on the New Madrid Fault, in the southeastern corner of the state.

A new USGS report identifies 17 regions that have been the site of induced earthquake activity. I’ll look at that report in the next post. Missouri is not one of 17 regions. It is perplexing, then, to wonder what might be causing such a large increase.


The data on Missouri earthquake frequency and the map of Missouri earthquakes both come from the USGS Earthquake Archives Data Portal, http://earthquake.usgs.gov/earthquakes/search.

To create the frequency charts, I downloaded data as a CSV file and processed it in Microsoft Excel. On the data portal page, I set the north limit as 40.964, the south limit as 35.729, the west limit as -95.999, and the east limit as -89.099. I set the starting date at 1980-01-01 00:00:00, and the ending date at 2014-12-31 23:59:59. I set the minimum magnitude to 2, and the maximum magnitude to 8.

To create the map, I used the same geographic limits, same ending date, and same magnitude limits. But I set the starting date to 2008-01-01 00:00:00.

Peterson, Mark, Charles Mueller, Morgan Moschetti, Susan Hoover, Justin Rubinstein, Andrea Llenos, Andrew Michael, William Ellsworth, Arthur McGarr, Austin Holland, and John Anderson. 2015. Incorporating Induced Seismicity in the 2014 United States National Seismic Hazard Model – Results of 2014 Workshop and Sensitivity Studies. USGS Open-file Report 2015-1070. http://pubs.usgs.gov/of/2015/1070.

Birds Are On the Rebound…Or Not

Source: North American Bird Conservation Initiative, 2014.

Source: North American Bird Conservation Initiative, 2014.

Since 2009, wetland birds, coastal birds, and grassland birds have increased in numbers, while aridland birds, eastern forest birds, and western forest birds have declined. So says a report from the North American Bird Initiative. The changes are shown in the first chart at right, and discussed in the bullet points below. The second chart at right shows the trends over time.

(For larger view, click on chart.)

  • Wetland bird indicators increased more than 15%, continuing an uneven trend that began around 1995.
  • Coastal birds increased roughly 8%. Here the trend is split, however.
    Source: North American Bird Conservation Initiative, 2014.

    Source: North American Bird Conservation Initiative, 2014.

    Migratory shore birds have been in decline since 1985, and that trend continues. These birds use our coastal areas as part of long migrations between Canada and the Caribbean or South America. Winter coastal species, however, have been gradually increasing since about 1998. These birds spend the winter in our coastal regions, then migrate northward during the summer.

  • The small increase in grassland birds reverses a long decline that started in the early 1970s.
  • The trends for inland birds (non-coastal) are shown in the second chart at right.
  • Aridland birds decreased the most, more than 5% since 2009. This continues a decline that has been occurring since at least 1970.
  • Eastern forest birds and Western forest birds also declined, both continuing trends going back to 1970.
  • Three categories of birds have declined more than 30% since 1970: aridland birds, grassland birds, and eastern forest birds.

PrimaryHabitats_CONUS2014_1000pxWhere birds are on the rebound, the report attributes it to successful conservation efforts to restore essential habitat. Where birds continue to decline, it is because habitat continues to be lost. The map at right shows the continental United States, and the colors match the habitats used in the report. Light green is eastern forest, light yellow is grassland. Missouri is primarily grassland and eastern forest. Previous posts in this blog focused on threatened species (here), land use in Missouri (here), on the fragmentation of forestland in Missouri (here), and on urban sprawl (here).

Why do birds matter? Why do people count them? First of all, some people love them. Beyond that, however, have you ever heard the saying “The canary in the coal mine?” Do you know what it means? Coal miners face many deadly dangers. Among them is the undetected seepage of poisonous gas into the mine. In olden days, they didn’t have fancy electronic detectors to warn them. Instead, they took a canary in a cage down into the mine. If suddenly the bird died, it meant that poisonous gas was building up in the mine.

Bird counts serve a similar purpose. If their numbers decline, it warns us that essential habitat is being lost, that the earth’s capacity to support life is being eroded, that we need to take action to prevent a greater disaster from occurring.

Source: Texas Parks and Wildlife Department

Source: Texas Parks and Wildlife Department

The report contains no information specific to Missouri beyond what can be read from the map shown above. One important habitat that does not show up well on the map is inland wetland. Missouri sits on the Mississippi Flyway, one of the most important paths for migrating birds (shown in a second map at right.) During the spring, the birds travel up the Mississippi River from the Gulf Coast. They continue up the Mississippi, or they branch out along the Ohio, Missouri, and Illinois Rivers. Some go as far as northern Alaska. During the fall, they return the way they came.

Don’t think of these birds as using only the major rivers. Think of them using Missouri’s forests, fields, lakes and streams as feeding stations and stopover points on their long, long journey. Nearly half of North America’s bird species, and about 40% of its waterfowl, spend at least part of their lives in the Mississippi Flyway.


North American Bird Conservation Initiative, U.S. Committee. 2014. The State of the Birds 2014 Report. U.S. Department of Interior, Washington, D.C.

Texas Parks and Wildlife Deptartment. Map of Mississippi Flyway, Downloaded 11/23/14 from http://www.tpwd.state.tx.us/huntwild/wild/birding/migration/flyways/mississippi.

Audubon Society, Mississippi Flyway, http://conservation.audubon.org/mississippi-flyway.

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