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Earthquakes in Wichita?

Thu ,28/01/2021

Earthquakes in the Wichita area are very rare. However, beginning in November 2020, a cluster of earthquakes occurred with the epicenters under Northeast Wichita. There were 21 earthquakes with a magnitude above 2.5 (M2.5) on the Richter scale. The largest of those was an M3.9 on December 30 which could be felt as far as 30 miles away. Many people thought the earthquakes were caused by disposal wells in the area, but the Kansas Corporation Commission (KCC) and the Kansas Geological Survey (KGS) investigated and found that there were only six disposal wells within a 6 mile radius and together they were only injecting a modest 9000 barrels of wastewater a day. That may seem like a lot, but it is a relatively small quantity compared to disposal wells in Harper and Sumner Counties where regulators found dozens of wells in 2016 pumping as much as 15,000 barrels a day. So, the investigators concluded that there was no link between the earthquakes the disposal wells near Wichita. And the investigators were mostly right. The earthquakes were likely caused by disposal wells as far as 55 miles away.

There were only two or three quakes a year in Kansas and Oklahoma before 2009. That was when fracking operations began in Oklahoma and millions of gallons of wastewater were pumped into disposal wells. The graph below shows the number of earthquakes per year in the central United States. The number of earthquakes, mostly in northern Oklahoma and southern Kansas, went to over 1000 a day by 2015, with one in Oklahoma in 2016 being an M5.8 earthquake. It was felt as far away as Illinois and caused an estimated $600,000 worth of damage in Wichita. When the Oklahoma Corporation Commission and the KCC put a limit on the amount of disposal fluid that could be injected into each well, the number of earthquakes fell off appreciably.

In Kansas, fracking started later, but earthquakes soon emerged as a problem as the number of disposal wells grew to more than 16,000 by 2015. Some of them were injecting as much as 15,000 barrels each day. In response to the induced earthquakes they caused, the KCC put a limit on the amount of fluid that could be injected into disposal wells within a 6 mile radius of earthquake epicenters. However, later research by the American Geophysical Union found that earthquakes could be caused by disposal wells as far as 55 miles away.

Most disposal wells inject fracking fluids into the Arbuckle zone because it is porous enough to take up the fluid. The extra fluid has to go somewhere, so it migrates outward from the injection wells, causing an increase in the fluid pressure, dP, ahead of it. The Arbuckle zone lies under the entire region, and the increase in pressure is moving North and East in the zone. When the increase in pressure, dP, reaches about 50 PSI as shown in pink, it starts destabilizing and causing slippage in ancient faults. The graph below shows how the dP has changed in south-central Kansas over the past several years, and its migraton can be identified with new clusters of earthquakes.

When the pink area (dP > 50 PSI) reached Reno County in 2017, the area began experiencing quakes. Since then, the county has experienced 126 earthquakes of a magnitude 2.0 or greater. The magnitude seems to the increasing over time.  Hutchinson experienced an M4.2 quake in 2019 and an M4.6 earthquake on 01/19/2021, which was felt in 20 states. In 2018, Burrton, situated between Hutchinson and Wichita, had an M4.2 earthquake. One of Burrton’s school buildings was damaged and hasn’t been used since then.  The map only goes to 2017, but the disposal fluid has been migrating outward since then, with the pink area, dP > 50, likely reaching Wichita in 2020. And that’s when the earthquakes began. Judging from Hutchinson’s experience, future earthquakes in the area may be stronger.

Since the earthquakes are clearly caused by the volume of fluid injected by the disposal wells, the industry should be accountable for the damage done to private and public property. In the period 1990-2012, there were only 16 earthquakes at M2.5 or greater magnitude in KS. Only one of those was greater than M4.0 and only one was near Wichita, about 15 miles East. From 2013 until today, there have been 730 earthquakes of M2.5 or greater in Kansas, 220 of them M3.0 or greater, and 9 of M4.0 or greater. The Richter scale is a logarithmic scale, so an M3 .0 quake is 10 times stronger than an M2.0 quake, and dissipates 32 times more energy. Earthquakes over M2.0 can be felt, those over about M3.5 can cause minor damage, and those over M4.0 are strong enough to do structural damage to buildings and infrastructure.

The earthquakes in Oklahoma have done millions of dollars in damages, but lawsuits to recover damages have been unsuccessful as it is not possible to link one disposal well with any given earthquake. One reasonable proposal was to have the disposal companies voluntarily create a fund which could be used to reimburse injured parties for damages. Since damages are caused by the total volume of fluid, it would be reasonable to apportion the cost among the disposal companies according to the amount of fluid they inject.

Certainly, regulations are needed to protect people’s property in Kansas. Current regulations, imposed by the KCC, only limit disposal volumes within 6 miles of earthquake epicenters. An effort to put limits on the volume of disposal fluid, KS HB 2641, failed when it died in committee. The Kansas KCC and KGS need to re-examine the research and put new guidance in place to regulate disposal wells and guide the legislature in protecting the public and private property in Kansas.

Kansas has not had exceptionally strong earthquakes yet. It has a unique opportunity to learn from what happened in Oklahoma, and take action to limit induced earthquakes and any costs to Kansas citizens. Effective agreements with the industry – or good legislation is needed to:

  1. restrict the location of disposal wells.
  2. limit the amount of wastewater that can be disposed of at a site.
  3. limit the pressure which can be used to inject the wastewater.
  4. require that any disposal well linked to significant seismic activity be further regulated.
  5. require that disposal well companies create a fund or carry liability insurance to pay for earthquake damage.

Without effective action, the earthquakes are likely to grow worse. If the disposal wells connot be regulated, then at least the disposal well companies should compensate people and taxpayers for the damage.

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