Ben Andrews never imagined his job would involve simulating volcanic eruptions with talcum powder and lasers.

But in retrospect, his career seems almost fated. In May 1980, Mount St. Helens erupted about 50 miles from his parents’ home in Portland, Ore. — the worst volcanic eruption in U.S. history. Ash rose 80,000 feet into the air and fell onto 11 states; landslides, mudslides and avalanches of hot rock and gas obliterated more than 200 square miles of forest; 57 people were killed. Andrews’s mother was seven months pregnant with him at the time.

In a photo taken shortly after his birth, Andrews’s father holds him up for the camera while a dark plume of ash darkens the sky behind them. As he grew up, Andrews would gaze at the mountain from his bedroom window. It was like a tiger, he said — beautiful and wonderful and dangerous.

Now Andrews is the director of the Global Volcanism Program at the National Museum of Natural History in the District — far from the seething activity of the Cascades. To understand volcanoes’ inner workings and protect people from the perils they pose, he must create his own eruptions.

Pyroclastic flow from an Aug. 7, 1980, eruption stretches from Mount St. Helens's crater to the valley floor below. (USGS)

Andrews’s experimental volcanology lab, completed in 2013, consists of a nearly 5,000-square-foot tank made from plywood and plastic sheeting housed in a windowless room at the Smithsonian’s Museum Support Center in Suitland, Md. Blue, green and red lasers are arrayed throughout the tank, alongside cameras and temperature sensors. Outside there is a computer, several bags of talc, and a table bearing a toaster oven. Everything — the floor, the table, Andrews’s clothes — is covered in a fine layer of white powder.

The toaster oven dings. “That’s how you know the eruption is ready,” Andrews quips.

Wearing a respirator to keep the grit from his lungs, he retrieves a kilogram container of talc from the oven, where it was just heated to 250 degrees. He climbs a ladder to the top of the tank and spreads the hot powder onto a conveyor belt. A colleague switches off the lights.

“We’re off to the races!” Andrews clambers down from the ladder and presses his face against one of the tank’s transparent plastic windows.

The powder on the conveyor belt is pouring into the tank, a billowing river of material. The lasers illuminate it in cross sections — a vertical green beacon catches the rising cloud of warmer, lighter material; horizontal blue and red beams show the flow of powder spreading to the sides. In this multicolored light, the eddies and swirls in the dust stream recall the glimmer of oil on water.

The experiment is beautiful but tame — not much like the hot, dense currents of gas, ash and boulders called pyroclastic flows that Andrews is trying to understand. Those flows are among the most deadly aspects of an eruption, blasting out of volcanoes at speeds faster than a car can go and exceeding temperatures of 1,000 degrees Fahrenheit. Flows from Mount Vesuvius buried the ancient Roman city of Pompeii; deposits from the most recent eruption of the Yellowstone supervolcano half a million years ago suggest those pyroclastic flows traveled a whopping 50 miles.

From a distance, these flows may look like fluffy clouds. But in reality, Andrews says, they are “superheated, sandblasting destruction.”

“For most natural eruptions, especially the big ones, we don’t see them happening,” he continues. “This is a good thing” — most witnesses to such an event don’t live to tell the tale. “But if a pyroclastic flow happens, we would like to know how fast it is going to go, where is it going to go, how far.”

Ben Andrews heats talcum powder for his indoor eruption. (Monica Akhtar/The Washington Post)

The currents in Andrews’s chamber contain particles no wider than a human hair. They’re barely warmer than room temperature, and you could easily outrun them. But they behave according to the same laws of physics as a pyroclastic flow, which makes them an ideal model.

“Essentially, this is a scaled-down version of an eruption,” Andrews says. “A thousand times colder, a hundred times slower, a hundred times less dense, a hundred times safer and a hundred times less terrifying.”

Andrews hopes his experiments will illuminate the factors that cause a pyroclastic flow to move swiftly over land, where it may threaten people, or lift off into the air, where it may engulf planes. The results will also help scientists understand ancient flows based on the deposits they left behind — essential knowledge for when those volcanoes erupt again. In turn, that research might help officials figure out whom to evacuate when the next mountain begins to rumble.

Tales From the Vault: Science museums are home to vast research collections, most of which the public never gets to see — until now. Speaking of Science goes behind the scenes at our favorite museums to introduce readers to the fascinating objects and people we find there. Read past installments here.

Correction: An initial version of this article misstated the amount of talcum powder Andrews uses in each experiment. 

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