Watch Homemade Lava Explode, for Science

When the Kilauea Volcano on the Big Island of Hawaii erupted in July, a “lava bomb” flew into the sky when the lava flowed into the sea and crashed onto a tourist boat that was anchored offshore. Nearly two dozen people were injured.

Now, scientists in upstate New York are brewing batches of homemade lava to simulate the most violent of volcanic explosions with spectacular effects.

The work is part of an ongoing study by the University of Buffalo’s Center for Geohazards Studies that is attempting to explain why a spontaneous explosion can occur when you add a bit of water to lava. To do this, researchers are creating microcosms of huge volcanic eruptions.

The extreme DIY experiment mimics a physical process called “molten fuel-coolant interaction.” This phenomenon describes the volatile behavior of lava in the presence of water. Sometimes ice, lakes, oceans, and underground water can trigger sudden blasts of lava and rock in the event of a volcanic eruption.

Water and lava are historically bad partners. Iceland’s Eyjafjallajökull volcano erupted beneath a glacier in 2010, creating a 33,000-foot-high ash plume when magma and water interacted with one another that grounding flights throughout Europe for a week.

“There are not many places that conduct experimental work on magma-water interaction with [molten rock],” Ingo Sonder, the project’s lead investigator and a research scientist at the Center for Geohazards Studies, told Motherboard. The team’s findings were published to the Journal of Geophysical Research: Solid Earth on Monday.

To simulate an explosion, the scientists first had to make lava. The recipe called for basaltic rock—a common type of hard volcanic rock—and a whole lot of heat. Roughly 130 pounds of basalt were melted in an induction furnace at 2,400 degrees Fahrenheit for four hours to create 10 gallon batches. Then, it was poured into heat-resistant steel boxes ranging from 8 to 18 inches tall. Next, water was injected through special portals in the containers’ walls at speeds of 6 to 30 feet per second.

And finally, a ten-pound sledgehammer was dropped to kickstart a blast.

Sometimes only a little material was ejected from the lava. Other times there were “stronger reactions with visible steam jets” shooting 16 feet into the air, the study notes. Bits of volcanic glass called “Pele’s hair”—named for the Hawaiian volcano goddess—were also found around the site.

Sonder stressed that these early results “cannot be applied directly to nature,” but noted some trends. For example, dynamic explosions occurred when water was injected more quickly, and into taller containers. “I was surprised to see [this],” Sonder said. “Interaction intensity rises when we increase the height.”

Several attempts also produced explosions with water alone, before the sledgehammer was introduced.

A phenomenon called the “Leidenfrost effect” could explain some of the variability. When liquid is exposed to a much hotter substance, it can produce a protective film that prevents it from boiling. But when this doesn’t happen—for instance, when water is forcefully injected—the substances can mix. This causes the water to expand in volume, destabilizing the mixture, and produces the violent, spontaneous explosions we sometimes see in nature.

The experiment was conducted at the University of Buffalo’s Geohazards Field Station in Ashford, New York. Here, researchers model all sorts of large-scale (aka “too large for a lab”) geological events, such as the creation of volcanic craters by subsurface explosions. The station is even building its own rock melting facility.

Other labs have conducted similar experiments but at a smaller scale, the study notes. Much of the previous research relates to industrial safety at nuclear power plants.

“A long term goal of this research is to be able to provide threat-level analysis methods based on specific properties of a volcano,” Sonder said.