Driving around Southern California? You may notice a bubbling mud spring close to Highway 111 that LiveScience likens to a "geologic poltergeist." Called the "Slow One"—it's near tectonic plates expected to one day cause the "Big One," a giant earthquake—this mud spring has been around since 1953 and caught scientists' attention when it began shifting in recent decades. Then this year it moved 60 feet in a few months and 60 feet in a single day. Now it's menacing pricey fiber-optic cables, a petroleum pipeline, a Union Pacific freight rail track, and part of Highway 111. "It's a slow-moving disaster," a California fire and emergency official tells the LA Times. Imperial County even declared an emergency this year to curb the Slow One, to no avail.
Union Pacific constructed a 100-foot-long, 75-foot-deep underground wall of steel and boulders, but the Slow One just bubbled under it, approaching the tracks. Now Union Pacific has built temporary tracks on safer land and officials say part of Highway 111, which links the Cali-Mexico border to Interstate 110, could get shut down. What's more, the Slow One smells like eggs and would suffocate any unlucky person who tumbles into the 40-foot-deep sinkhole. Also called the Niland Geyser, it runs about 80 degrees Fahrenheit thanks to bubbling carbon dioxide. "It's a quirky thing," says geophysicist David Lynch, who has studied the mud spring. "If there was no railroad nearby, you wouldn't even know about it. This would just be something out there chewing out the desert." (One geyser erupted and poured out trash dating to the 1930s.)