What happens when lava meets water? (2024)

Published 10 december 2018 This content has been archived.

What happens when lava and water meet? Explosive experiments with man-made lava are helping to answer this important question.

By boiling 10-gallon batches of molten rock and injecting them with water, the researchers shed light on the fundamental physics of lava-water interactions, which are common in nature but poorly understood.

The project - a long-term, ongoing study led by UB - published its first results on December 10 in the Journal of Geophysical Research (JGR): Solid Earth.

The researchers caution that the number of tests so far is small, so the team will need to conduct more experiments to draw definitive conclusions.

The research shows that encounters between lava and water can sometimes cause spontaneous explosions if there is at least half a meter of molten rock above the mixing point. In previous, smaller-scale studies that used about the amount of lava in a coffee cup, researchers in Germany found that they had to apply an independent stimulus — essentially stippling the water in the lava — to trigger an explosion.

The results reported in JGR: Solid Earth also point to some preliminary trends, showing that in a series of tests, larger, more brilliant reactions tended to occur when water flowed in faster and when lava was stored in larger containers.

The team conducted a total of twelve experiments where the water injection rate varied from about 6 to 30 feet per second and lava was contained in insulated steel boxes that ranged in height from about 8 to 18 inches.

"When you think about a volcanic eruption, there are strong forces at work, and it's not a gentle thing," said lead researcher Ingo Sonder, a researcher at the Center for Geohazards Studies at UB. "Our experiments look at the fundamental physics of what happens when water becomes trapped in molten rock."

Sonder will discuss the project at a press conference on December 10 at 4 p.m. during the American Geophysical Union Fall Meeting in Washington, D.C.

The research was funded by the National Science Foundation. In addition to Sonder, UB co-authors included Andrew G. Harp, who contributed to the project as a UB doctoral candidate in geology and is now an instructor in geological and environmental sciences at California State University, Chico; Alison Graettinger, who contributed to the project as a postdoctoral fellow in geology at UB and is now an assistant professor of geosciences at the University of Missouri-Kansas City; Pranabendu Moitra, who contributed to the project as a postdoctoral researcher in geology at UB and is now a postdoctoral researcher in the Lunar and Planetary Laboratory at the University of Arizona; and Greg Valentine, UB professor of geology and director of the Center for Geohazards Studies. Ralf Büttner and Bernd Zimanowski from the Universität Würzburg in Germany also contributed.

In nature, the presence of water can make volcanic activity more dangerous, such as during previous eruptions of Kilauea in Hawaii and Eyjafjallajökull in Iceland. But in other cases the reaction between the two materials is moderate.

Sonder wants to understand why. 'Sometimes when lava hits water, you see enormous, explosive activity. Other times there is no explosion and the lava can simply cool and form some interesting shapes. What we do is try to learn about the conditions that cause the most violent forms. responses."

Ultimately, the results of the long-term project could improve scientists' ability to assess the risk that volcanoes near ice, lakes, oceans and underground water sources pose to people living in surrounding communities.

'The research is still at a very early stage, so we still have several years of work ahead of us before we can look at the whole range and combination of factors that influence what happens when lava or magma comes into contact comes with water,” says Valentine, research associate. -author and head of the Center for Geohazards Studies at UB.

“But everything we do is with the intention of making a difference in the real world,” he says. “Understanding fundamental processes involved in volcanoes will ultimately help us make better predictions when it comes to eruptions.”

Interactions between lava and water are associated with a phenomenon known as 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 area has been done in the context of industrial safety, with an emphasis on understanding potential hazards in nuclear power plants and metal production sites.

The lava water experiments build on previous research in this area and focus on molten rock.

The work will take place at the Geohazards Field Station in Ashford, New York, about 40 miles south of Buffalo. Operated by the UB Center for Geohazards Studies, the facility provides scientists with a place to conduct large-scale experiments that simulate volcanic processes and other hazards. These tests allow scientists to control conditions in ways not possible at a real volcano, such as dictating the shape of the lava column and the rate at which water shoots into it.

To make lava, researchers dump basalt rock into a powerful induction furnace. They heat it for about four hours. When the mixture reaches a red-hot 2,400 degrees Fahrenheit, it is poured into an insulated steel box and injected with two or three jets of water.

Then a hammer drives a piston into the mixture 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 many different physical processes that can take place when lava and water meet.

"The system's response to water injection ranged from mild, evaporation-dominated processes, where only a small amount of melt was ejected from the container along with some steam, to stronger responses with visible steam jets and with melt domains ejected up to several meters in. height." the researchers wrote in JGR: Solid Earth.

The study did not investigate why enclosure height and water injection rate corresponded to the largest explosions. But Sonder, whose background is in geosciences and physics, offers some thoughts.

He explains that when a blob of water is captured by a much hotter substance, the outer edges of the water evaporate and form a protective film that encloses the rest of the water like a bubble, limiting heat transfer to the water and preventing it from it's going to boil. . . This is called the Leidenfrost effect.

But when water is injected quickly into a tall lava column, the water—which is about three times lighter than the lava—will rise and mix more quickly with the molten rock. This can destabilize the vapor film, Sonder says. In this situation, the unprotected water would quickly expand in volume when heated, putting severe pressure on the lava, he says. The result? A violent explosion.

In contrast, when water is slowly injected into shallow lava pools, the protective vapor film can trap, or the water can reach the surface of the lava or escape as steam before an explosion occurs, Sonder says.

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