Cushing, Oklahoma was rocked by an Mw5-Mw5.3 earthquake last night.
The earthquake’s epicenter was located just 2 miles west of the city. Cushing is of note because it is the pipeline crossroads of the US, and home to a massive oil storage facility.
The earthquake appears to have been a doublet—two earthquakes very closely spaced in time (within a second of each other). Distant seismographs will record this as one event. Some of the strongest ground shaking yet were recording by strong motion sensors near the epicenter. The earthquake (or quakes) were shallow, even for Oklahoma, and damage to the town of Cushing appears significant, particularly to unreinforced masonry structures. Several pipelines at the oil facilities around the town were also shut down as a precaution. No deaths have been reported, although some minor injuries have. It’d be a different story if this quake occurred during daylight, business hours, when people would be out and about on the street.
Cushing is not only a crossroads of pipelines, it’s also a crossroads of faults. The Wilzetta is a major fault system that strikes southwest to northeast across several Midwestern states. At Cushing there are multiple east-west striking faults that have revealed themselves because of earthquakes (they weren’t at least not publically, known. Whether the oil industry knows depends. Subsurface data acquired privately is proprietary). Evidence suggests these intersecting faults can cause larger quakes on major fault systems. This has happened in California.
We know the basics as to why the earthquakes are happening in Oklahoma and I don’t need to rehash them. Whether this earthquake was induced by wastewater injection recently, or triggered by other earthquakes induced by wastewater injection remains to be seen. I suspect we’ll find a high-volume wastewater injection well close to the epicenter of this quake, a well that is still in operation despite the state’s Band-Aid measures. But this study, which I’ve linked to many times before, basically says in scientistese that, hey, maybe it’s time for the experiment to end, especially near Cushing, OK.
Earthquakes within the Cushing sequence are of particular interest because of their proximity to critical energy industry infrastructure. Based on results from this study and the similarity of the conjugate strike-slip fault systems in Cushing and Prague, we suggest that a moderate-magnitude (Mw 5.6) earthquake, similar to the 2011 Prague earthquake (Mw 5.6), could occur at the conjugate fault intersection directly beneath the Cushing oil storage facility. The Oklahoma Geological Survey (OGS) reports that the immediate vicinity of the 2011 Prague Mw 5.6 epicenter experienced very strong shaking of intensity levels (MMI VII = 18–34% g) (Okalahoma Geological Survey, 2011, www.okgeosurvey1.gov/...). Shaking intensity of MMI VII could cause moderate to heavy damage to storage tanks in the Cushing facility depending on the tank height, diameter, and percent full [O'Rourke and So, 2000].
It is interesting to note that the felt shaking intensity in the Prague epicentral region was significantly stronger than predicted for central Oklahoma in the USGS National Seismic Hazard Model (NSHM) (2% probability of exceedance in 50 years = 6–10% g) [Petersen et al., 2014]. In the 2014 NSHM, all earthquakes in central Oklahoma were considered induced and thus were not included in the hazard calculations. As a consequence, the recent increased seismicity rate contributes to higher hazard that is not reflected in the NSHM for central Oklahoma. If induced earthquakes are included in the NSHM or if the increased seismicity in Oklahoma over the past several years is a natural process, instead of induced by wastewater injection, maximum shaking levels in the NSHM significantly increase. As a model sensitivity experiment, Petersen et al. [2015] included all of the increased seismicity in Oklahoma, including relocated calibrated hypocenters from McNamara et al. [2015] and this study in a 1 year NSHM. Inclusion of all recent Oklahoma earthquakes in the NSHM significantly increases ground shaking estimates and earthquake hazard (0.04% probability of exceedance in 1 year = 50–200% g = MMI X+), which would result in serious implications for infrastructure design standards.
Oops.
One good thing—the Oklahoma Supreme Court unanimously voted some time ago that yes, residents can sue, so expect lawsuits, hopefully lots of them.
After the election, I’ll be organizing everything I’ve written on the subject since 2012.
IN OTHER NEWS
Seaside, Oregon is going to try again. A bond measure is on the ballot tomorrow, intended to raise funds to move Seaside’s schools out of the tsunami zone. Most of Seaside is in the inundation zone, including 3 of its 4 schools. A previous bond measure failed in 2014. When I researched why, I learned that Seaside has a large population of residents who do not actually live there full-time---and they get to vote too. People familiar with places populated by “second-homers” (like much of Florida, for example) will find this familiar. People who live in the place full time will want to raise funds for some service (like education.) People from Away and their local interest groups will overwhelm full-time resident voters.
All four of Seaside’s schools are not retrofitted. When the big one hits, it’s unlikely they’ll remain standing. Oregon provides funding for retrofitting, just not to structures in the tsunami inundation zone.
The odds of a Cascadia quake (an M8 to M8.5, on its southern segment) in the next 50 years are about one in three.
Oh, and not to be undone, Oregon State University is moving forward with a new marine science facility in Newport, in the tsunami inundation zone. I continue to be flabbergasted by this; the research group which determined how many times over the last 10,000 years Cascadia has ruptured (43, 19 of them at least M9 or greater), is based at Oregon State University. If you’re wondering why the state hasn’t put a stop to this, it’s because there’s a caucus of legislators, community leaders, developers, and others who would rather the earthquake problem not be a thing, or a thing to be dealt with in the very far future. Oregon’s coastal development rules do not have much teeth (nor do Washington’s, for that matter.)
Perhaps the New Yorker needs to commission more scary articles. I recommend sending someone to Japan. Scenes like this one, where a man learned to scuba dive so he could find his wife’s remains after she and her coworkers were taken by the sea after the Big One in 2011[1], will absolutely happen in the Pacific Northwest too.
[1] 95%+ of those who died in the quake drowned. The rest were due to heart attacks, building collapses, exposure to cold weather, and other onshore hazards. This part of that quake’s story has been overshadowed by the nuclear power plant accident.