Words by Sheri Baer
On an ascent up the north side of Mount Shasta, Andy Calvert pauses to munch down a Clif Bar at 13,000 feet. Making small talk with the U.S. Forest Service climbing rangers accompanying him, he points over to a dome at the top of the Hotlum Glacier, a formation known for its treacherous gullies and crevasses. “Someday, I want to go get a piece of that,’” he casually remarks. The response: “There’s a pretty good snow bridge, we could just do it now.”
One “steep, icy and scary” rope belay later, Andy had his sample. “I felt like I was flying,” he recalls. “It was like I was flying out to get this rock and come back.” Certainly not a typical day on the job in Silicon Valley, but as a local scientist with the U.S. Geological Survey (USGS), Andy is charged with deciphering the eruptive history of volcanoes in order to predict future threats. “I have to get a rock sample from every lava flow I can get to,” he explains. “It’s probably 50-50 whether we’ll get a non-Mount St. Helens eruption in the Western U.S. in our lifetimes, but we should still be ready for it.”
Looking back, Andy credits Mount St. Helens’ catastrophic 1980 eruption with inspiring his eventual volcanic-rock strewn path. As a seventh grader living over 200 miles away in Moscow, Idaho, he vividly remembers what went down (or rather, up) on May 18. “It was a beautiful sunny day,” he recounts, “and then this cloud started coming over and it got as dark as the darkest night.”
ABOVE: Andy shows a photo of the 1980 eruption of Mount St. Helens (Photo: Annie Barnett) / COVER IMAGE: Andy (third from left) and team spent two weeks mapping and sampling Mount Shishaldin volcano on Unimak Island, Alaska. (Photo: Courtesy of Matt Loewen - USGS)
After the eruption, half an inch of ash blanketed the city, triggering the cancellation of the last three weeks of school. “That made volcanoes even more interesting,” Andy grins. “I knew something about geology before then, but that was what really taught me that the Earth is dynamic.”
Initially eyeing medical school as a Stanford University undergrad, Andy enrolled in a geology class recommended by a friend. “The class was at 8 o’clock in the morning, and I just couldn’t wait for it,” he recalls. “It was like falling in love.” Andy signed up for another class called Rocks and Minerals. “I thought, ‘Well, that sounds really boring, so if I like that too, I’ll be a geologist.’”
Metamorphic rock—gneiss, schist and slate. Smooth. Coarse. Shiny. Opaque. Utterly captivated, Andy followed his heart.
Andy at the USGS lab at Moffett Field in Mountain View. (Photo: Annie Barnett)
After earning bachelor’s and master’s degrees from Stanford, Andy completed his doctorate at UC Santa Barbara. As he was wrapping up his studies, he caught wind of an opening for a geochronologist with the USGS volcano hazards team based in Menlo Park and got the job. “Our group looks at volcanoes in a variety of different ways,” he clarifies. “I date rocks. My specialty is time. I provide the time context for eruptive behavior.”
Here’s why time matters: Volcanoes that have been active in the last 10,000 years can potentially wreak havoc again. Andy unfurls what looks like a paint-by-numbers map of Mount Shasta. “Each one of these is a discrete eruption or a series of eruptions,” he describes, gesturing to color splashes ranging from purple (older than 350,000 years) to oranges and reds (a specific eruption 10,700 years ago) to pink (“all younger than that”).
Andy describes the eruptive history of Harrat Rahat to members of the Saudi Geological Survey after a five-year study of the seismic and volcanic hazard to the holy city of Medina, Saudi Arabia. (Photo: Courtesy of Tom Sisson - USGS
Whether it’s Shasta, St. Helens, Lassen Peak, Hood or Rainier, tracking past behavior lays the foundation for creating long-term hazard assessments. “We educate people about what the mountain is capable of,” Andy summarizes. “What can happen and whether we should worry.”
Although his geologic focus is the Western U.S., Andy estimates he’s visited over 50 volcanoes in locales like New Zealand, Guatemala, Italy and Saudi Arabia. Any given day might find him on the top of a ridge or “slogging through some really terrible places.” His professional tool kit includes ice training, mountaineering skills, glacier travel, wilderness first aid, bear deterrence and “getting in and out of helicopters in pretty gnarly spots.”
Andy calls out his field work in Alaska as especially memorable. “I love being up high on these volcanoes,” he says. “You’re dropped off and then that big, smelly, noisy helicopter goes away and you’re left with quiet.”
Andy shows a draft map of Mount Shasta, where different colors visualize deposits from volcanic eruptions over thousands of years. (Photo: Annie Barnett)
Since Andy was hired by the USGS in 2001, he and his wife, Amy McLanahan, have lived in Palo Alto, Menlo Park, San Mateo and most recently, Belmont. Raising their family here (their son and daughter are now in their 20s) offered myriad opportunities to explore the Peninsula’s own unique geology —particularly on excursions to the coast. “We’re in a pretty amazing part of the world because we can drive over to Half Moon Bay and go from one huge tectonic plate, the North American Plate, onto the largest plate, the Pacific Plate,” observes Andy. “My kids get so sick of me saying, ‘Ooop! Crossing to the Pacific Plate!’”
During his five-year term as scientist-in-charge of the California Volcano Observatory, Andy helped oversee the USGS move from Menlo Park to Moffett Field in Mountain View. He’s currently diving back into research (including Mount Shasta mapping), where he still relies on the basic tools he first learned to use at Stanford: a hammer and a hand lens. However, Andy fully appreciates Moffett’s brand new lab and state-of-the-art technology. “We have equipment we use to measure the ages of rocks that’s pretty fancy,” he affirms. And what a way to calibrate accuracy: testing rocks from the 79 AD eruption of Mount Vesuvius. Nodding to a noble gas mass spectrometer, Andy breaks into a wide, schoolboy smile. “We took crystals from that eruption and ran them on that machine there and we got the right answer!”