Scientists brew lava and blow it up to better understand volcanoes

Large-scale volcanic experiments

Lava-water interactions are associated with a phenomenon known as a molten fuel coolant interaction, in which a liquid fuel (a heat source) reacts violently with a liquid coolant. Much of the experimental work in this field has been done in the context of industrial safety, with a focus on understanding potential dangers in nuclear power plants and metal production sites.

The lava-water experiments build on previous research in this area, while focusing on molten rock.

Protective gear. Credit: Douglas Levere / University at BuffaloProtective gear. Credit: Douglas Levere / University at Buffalo

Protective gear. Credit: Douglas Levere / University at Buffalo

The work takes place at UB’s Geohazards Field Station in Ashford, New York, some 40 miles south of Buffalo. Run by the UB Center for Geohazards Studies, the facility gives scientists a place to conduct large-scale experiments simulating volcanic processes and other hazards. In these tests, researchers can control conditions in a way that isn’t possible at a real volcano, dictating, for example, the shape of the lava column and the speed at which water shoots into it.

To make lava, scientists dump basaltic rock into a high-powered induction furnace. They heat it up for about 4 hours. When the mixture reaches a red-hot 2,400 degrees Fahrenheit, it’s poured into an insulated steel box and injected with two or three jets of water.

Lava that has been ejected from the container cools after the explosion, forming bits and strands of glossy, black rock. By analyzing fragments like these, researchers can gain knowledge about how volcanic rock formations found in nature are formed. Credit: Douglas Levere / University at BuffaloLava that has been ejected from the container cools after the explosion, forming bits and strands of glossy, black rock. By analyzing fragments like these, researchers can gain knowledge about how volcanic rock formations found in nature are formed. Credit: Douglas Levere / University at Buffalo

Lava that has been ejected from the container cools after the explosion, forming bits and strands of glossy, black rock. By analyzing fragments like these, researchers can gain knowledge about how volcanic rock formations found in nature are formed. Credit: Douglas Levere / University at Buffalo

Then, a hammer drives a plunger into the mix to help stimulate an explosion. (In some cases, if enough molten rock was present above the injection point, an intense reaction began before the hammer fell).

In addition to identifying some preliminary trends, the published study attests to the wide variety of physical processes that can occur when lava and water meet.

“The system response to water injection varied from mild, evaporation-dominated processes, in which only a little melt was ejected from the container alongside some steam, to stronger reactions with visible steam jets, and with melt domains ejected to several meters height,” the scientists wrote in JGR: Solid Earth.

Red-hot. Inside the furnace, rock has begun to melt to form lava. Credit: Ingo Sonder / University at BuffaloRed-hot. Inside the furnace, rock has begun to melt to form lava. Credit: Ingo Sonder / University at Buffalo

Red-hot. Inside the furnace, rock has begun to melt to form lava. Credit: Ingo Sonder / University at Buffalo

The study did not examine why box height and water injection speed corresponded with the biggest explosions. But Sonder, whose has a background in geosciences and physics, offers some thoughts.

He explains that when a blob of water is trapped by a much hotter substance, the outer edges of the water vaporize, forming a protective film that envelops the rest of the water like a bubble, limiting heat transfer into the water and preventing it from boiling. This is called the Leidenfrost effect.

After water is injected into the lava, this hammer drives a plunger into the mix to help stimulate an explosion. In some cases, if enough molten rock is present above the water injection point, an intense reaction begins before the hammer falls. Credit: Douglas Levere / University at BuffaloAfter water is injected into the lava, this hammer drives a plunger into the mix to help stimulate an explosion. In some cases, if enough molten rock is present above the water injection point, an intense reaction begins before the hammer falls. Credit: Douglas Levere / University at Buffalo

After water is injected into the lava, this hammer drives a plunger into the mix to help stimulate an explosion. In some cases, if enough molten rock is present above the water injection point, an intense reaction begins before the hammer falls. Credit: Douglas Levere / University at Buffalo

But when water is injected rapidly into a tall column of lava, the water — which is about three times lighter than the lava — will speed upward and mix with the molten rock more quickly. This may cause the vapor film to destabilize, Sonder says. In this situation, the unprotected water would expand rapidly in volume as it heated up, imposing high stresses on the lava, he says. The result? A violent explosion.

Credit: Bob Wilder / University at BuffaloCredit: Bob Wilder / University at Buffalo

Credit: Bob Wilder / University at Buffalo

In contrast, when water is injected slowly into shallower pools of lava, the protective vapor film may hold, or the water may reach the lava’s surface or escape as steam before an explosion occurs, Sonder says.

He hopes to explore these theories through future experiments: “Not a lot of work has been done in this field,” he says, “so even some of these basic processes are really not well understood.”