As Interstate 10 snakes through the mountains and toward the golf courses, housing tracts and resorts of the Coachella Valley, it crosses the dusty slopes of the San Gorgonio Pass. The pass is best known for the spinning wind turbines that line it.–

But for geologists, the narrow desert canyon is something of a canary in the coal mine for what they expect will be a major earthquake coming from the San Andreas fault. The pass sits at a key geological point, separating the low desert from the Inland Empire, and, beyond that, the Los Angeles Basin.

Through it runs an essential aqueduct that feeds Southern California water from the Colorado River as well as vital transportation links. It’s also the …