HMM – Margaret Mangan didn’t sleep well in the weeks following the Ridgecrest, Calif., earthquakes. The July shaking triggered a swarm of smaller tremors in the nearby Coso Volcanic Field, a cluster of lava domes and cinder cones at the northern end of the Mojave Desert. And it was Mangan’s job to watch for a possible eruption. “We were pretty much on 24-7 vigilance,” said Mangan, the longtime scientist-in-charge of the U.S. Geological Survey’s California Volcano Observatory. For several weeks, she personally monitored thousands of quakes via an automated alert system that pinged her phone at all hours.

Occasionally, she had to wake a colleague in the middle of the night to make sure the shaking pattern didn’t point to rising magma. California is famous for its catastrophic earthquakes and wildfires, but they are not the state’s only natural hazards. As head of the observatory, or CalVO, Mangan has drawn attention to the state’s more overlooked threats: a dozen restive volcanoes that stretch from Medicine Lake near the Oregon border to the Salton Buttes in the Coachella Valley. “Most people are surprised that there are any volcanoes in California,” said Kari Cooper, a geologist at the University of California, Davis. “It’s just really not on people’s radar.” READ MORE