Scientists have found out how a rare type of lava continues to move even after a year of volcanic eruption.
Researchers observed the motion of the rocky lava known as 'Obsidian flow' while visiting the Puyehue-Cordón Caulle volcano in Chile in January this year. The obsidian (volcanic glass) lava flow is still inching its way down, although the volcano stopped erupting in April 2012.
Unlike the other liquid red lava, obsidian lava is very thick and slow-moving, similar to a glacier. Rich in Silica, this type of lava, when it cools and solidifies, forms a natural glass called obsidian on the outside. The cooled volcanic glass slowly moves forward as a thick, black rock, covering the oozing lava inside.
"We found out that the lava was still oozing after almost a year and it advances between 1 and 3 metres a day. Although it moves slowly, it could speed up or collapse if it were to reach a steep hill, and gases trapped inside can suddenly explode, so it's like a lava with indigestion," Dr Hugh Tuffen, who led the international team of scientists.
"It looks like a solid cliff of crumbling rock up to 40 metres thick, that's as thick as ten double-decker buses, but we found that hidden beneath this crust there is hot, slowly-flowing lava, at up to 900 °C, which can burst out of the edges of the lava flow and help it move forwards. This was previously thought to only occur in hot red flowing or basalt lava, but we have found that thick obsidian lava is actually pretty similar to its runnier cousins," Tuffen said.
Recently, obsidian lava flow has been seen in the last three eruptions at Puyehue-Cordón Caulle volcano in Chile in 2011, 1960 and 1921. Obsidian from lava flows has been long considered as a prized material used for knives, arrowheads and cutting tools. It is also used in surgical applications due to its sharp cutting edges.
The finding has been is published in Nature Communications.
