A volcanic eruption is often not the explosive, flash-flood-of-lava affair that persists in the popular imagination, largely thanks to the notorious event at Mount Vesuvius in 79 AD. Rather, volcanic eruptions can be disasters in slow motion. This is currently the case in Hawaii, where Kīlauea, a shield volcano, is releasing a ponderous lava flow that is wreaking havoc on local communities and causing mass evacuations. But Kīlauea’s prominence in the recent news cycle is deceiving; in reality, the volcano has been insidiously erupting for 35 years.

Kīlauea’s slow-motion flow makes it the perfect candidate for time-lapse photography. Last year, Ph.D. student-turned-filmmaker Tyler Hulett ventured across Kīlauea to film Dawn of Fire, a short compilation of photographs that, when edited together and sped up, depicts the flow of a lava river. It was a dangerous project, the extent of which Hulett wouldn’t become aware until nearly a year later. Hulett and his friend, Hawaiian resident Lance Page, hiked six miles into Kīlauea’s lava field, where the surface layer of fresh lava is very delicate—“more the consistency of snow than rock,” Hulett told The Atlantic. “It was hard to get around because the ground was folded, twisted, and kept shattering.”

Although it was important to avoid the fresh lava, the real danger lay in what wasn’t visible. “There were numerous lava tubes that were invisible beneath us,” Hulett said. “One of our biggest fears out there was falling into these empty lava tubes if the ground collapsed. This new eruption has made it quite clear to me that, yes, we were walking over lots of invisible lava tubes.”