“It’s a slow-moving disaster.”
That may sound like an oxymoron but not to Alfredo Estrada, fire chief and emergency services coordinator of Imperial County, California — the state’s southernmost county on the border with Mexico where residents are less concerned about politics than they are about a strange phenomenon creeping across their land at an alarming rate that might be a sign California’s Big One earthquake may be starting right in their own backyard.
The “slow-moving disaster” is a mud spring – a geological formation which occurs when a moving underground liquid weakens the mudstone – a soft sedimentary rock – above it, causing a hole that fills with water. Like sinkholes, mud springs tend to get bigger, not smaller, as the land continues to collapse. The water bubbles are caused by carbon dioxide and other gasses, making them often smell like rotten eggs.
Why are geologists, residents, earthquake experts and doomsayers concerned about a bubbling cauldron in the ground so far from Northern California where the Big One is generally expected to hit? For one thing, Imperial County is where a corner of the North American plate rubs against a corner of the Pacific Plate, causing vibrations that run north along the connecting faults that include the San Andreas.
But the real reason for concern is that this mud spring at the start of the faults, which has existed for decades in relatively the same spot, is suddenly moving at an unprecedented rate for mud springs – up to 60 feet a day. A day! As a result, major infrastructures in the county are in danger, starting with Union Pacific Railroad tracks used for carrying massive amounts of freight through the county. The railroad has set up temporary tracks and redirected trains because a 100-foot long, 75 feet deep wall of boulders and steel did nothing to stop the mud spring. Draining the water didn’t help either – why do you think they call it a spring? Union Pacific is now considering a bridge over the mud spring. Meanwhile, local government officials are planning to shut down part of Highway 111 that’s in the direct path of the fast-approaching mud spring.
Outside of nervous residents of Imperial County — who are being warned to stay away from the 24,000-square-foot (for now) gurgling, unstable body of carbon dioxide-filled, oxygen-depleted, mud spring — who else should be worried? As expected, the government is playing down what is becoming known as The Slow One. U.S. Geological Survey geophysicist Ken Hudnut told the Los Angeles Times that, despite the fact that the mud spring is a result of earthquakes weakening the mudstone and causing deep cracks that release carbon dioxide, this speedy anomaly swallowing ground into its bad-smelling mouth at the starting location of the faults that could trigger The Big One are no cause for concern.