Cushing City Manager Steve Spears, an engineer by training, said people who have lived in the town a long time are not that concerned about potential danger. “We’ve all grown up with the tanks,” he said. “We all know what’s there. Steel is pretty plastic; it changes shape pretty well. So unless we have something really big, it’s not a concern.”

Spears said that while crude oil is flammable, it is not as dangerous as refined products such as gasoline. “I’d rather live next to the tank farm than the refineries in Tulsa,” he said.

And a number of safety measures are in place. The tanks are surrounded by berms capable of containing even very large spills, and the tank operators and area emergency responders have formed a safety consortium that coordinates preparations for and responses to even minor situations.

In 2013, the safety alliance conducted a disaster drill that assumed an F5 tornado strike, not a 6.0 earthquake.

Erdmann said tests and simulations indicate that even a structural failure would probably not cause Cushing tanks to split open or collapse, or even to lose much oil. More likely would be what’s called hydrodynamic hoop stress — a bulging or deformation caused by the sloshing of the oil and the tank’s floating roof — near the top of the tank.