The lava from Cumbre Vieja was “unusually fluid”, but with a devastating result
Archive photo of the La Palma volcano. /
science
The results of the study were recently published in the journal Nature Communications.
The lava ejected during the eruption of the Cumbre Vieja volcano on the island of La Palma in 2021 was
“unusually fluid, especially low viscosity, and fast”, concludes a study by the Johannes Gutenberg University of Mainz, in Germany.
This is one of the reasons why the destruction
"It was so devastating"The researchers underline in a statement made public this Tuesday by the university, in which they explain that the viscosity of the lava from the La Palma volcano was lower than, for example, that of that discharged by Kilauea in Hawaii in 2018.
The results of the study were recently published in the journal Nature Communications, in an article in which the authors describe that the La Palma event produced a basasite (volcanic rock) with one of the lowest viscosities of historical basaltic eruptions.
"The viscosity of the lava was one of the lowest ever observed in a
basaltic eruption«indicates Yves Feisel, who together with the scientist Jonathan Castro measured the viscosity of the lava in the laboratory, taking into account its chemistry, crystallinity and temperature.
As they explain, from the images of the lava flows that appeared on television and on the Internet, it was possible to see the speed at which the lava was moving and thus deduce its low viscosity.
Based on these filmed images, the researchers reached several conclusions. They calculated, for example, that
in some cases, the speed of the lava exit was greater than ten meters per second.
In addition, they were able to observe phenomena in lava flows that are normally more characteristic of fluids that circulate in a turbulent manner, such as those that occur within water masses.
But the researchers didn't just use television footage. To more accurately determine the viscosity of the lava, they collected solidified ash particles as they fell from the sky on La Palma.
Back at the University of Mainz, they were able to determine the temperature of the eruption by chemical analysis of these samples, which revealed that the magma must have been e
Between 1,150 and 1,200 degrees Celsius about.
They also melted some of the samples and measured the viscosity of the melt at these temperatures using a device known as a rheometer.
Shortly after the start of the eruption, the lava had
a viscosity between 10 and 160 pascals per second -the pascal second is the physical unit of viscosity-, points out Feisel, who adds: "That is a figure ten times lower than, for example, the viscosity of the lava discharged from Kilauea in Hawaii in 2018."
The team established that one of the reasons the destruction was so devastating was that the lava ejected during the eruption had
“an exceptionally low viscosity”which made it flow very quickly.
According to the scientist, the lava from Cumbre Vieja was so fluid mainly due to its specific chemical composition, in particular its relatively low silica content and the way in which this melt crystallized.
"When the lava cooled, crystals formed and this likely helped retain the lava's low silica content, allowing it to maintain its low viscosity for a longer period of time."
Although it is always very difficult to predict when and how volcanoes will erupt, the results of this research can help mitigate the damage caused by future eruptions, improving the prediction of the course and evolution of future lava flows.
The eruption of Cumbre Vieja in 2021 was the volcanic eruption «
longest and most disturbing in history recently from the Canary Island of La Palma«, recalls the university.
Images of lava flowing through settlements and into the sea went around the world, they say.
