You might not be able to find Cushing, Oklahoma on a map, but the magnitude 5 earthquake that occurred there over the weekend could have major implications for the way we think about induced seismicity and our national security. Cushing isn't just a town of about 8,000 people, it's where about a dozen oil pipelines intersect and pass through, as well as a major storage facility. Unfortunately, it's also the location of a reactivated fault (Source). The effects of increased wastewater injection on induced seismicity in the US is a topic examined in "The link between hydrofracking, wastewater injection and earthquakes: key issues for re/insurers", a Swiss Re white paper released earlier this year.
When you drive into Cushing, you'll see signs proclaiming it the "Pipeline Crossroads of The World" and it's true. This tiny town currently hosts about 58.5 million barrels of crude oil stock in Cushing according to the U.S. Energy Information Administration (Source). That's a lot of oil, an equivalent volume to 1,500 Goodyear Blimps (Source). This enormous volume is stored in many tanks around the town often called "tank farms." In previous earthquakes, damage to similar structures caused the release of 750 thousand gallons of aviation fuel (Anchorage, Alaska, 1964), the loss of the public water supply (Long Beach, California, 1933) and uncontrolled fire (Niigata, Japan, 1964) (Source). Thankfully, the structures in Cushing appear in tact after this earthquake, but a larger earthquake could create a real problem.
The M 5.0 earthquake occurred late on Sunday (November 6th) evening. While there are no reports of injuries yet, the United States Geological Survey (USGS) estimates about five thousand people experienced "Very Strong" shaking, or a "VII" on the Modified Mercalli Intensity (MMI) scale (Source). The strength of shaking is strongest near the epicenter and decreases radially outward, while magnitude is the same wherever the earthquake is experienced.
It's not clear if this event was directly influenced by wastewater injection, a process strongly linked to inducing seismicity (Source), but it is in a region that has seen a dramatic increase in seismic activity over the last five years (Source). This earthquake comes on the heels of a M 5.8 earthquake in September, the largest ever recorded in Oklahoma along a previously unknown fault. Scientists still debate the largest magnitude earthquake that could happen in Oklahoma, but a larger event in the Cushing region might damage the storage tanks and pipelines critical to the US oil and gas operations.
Category: Climate/natural disasters: Disaster risk, Earthquakes, Sustainable energy: Fossil fuel, Fracking
Location: Cushing, Oklahoma, United States