The planet’s “most infamous” volcano is seeing an uptick of activity in recent weeks, blasting off incandescent lava bombs and emitting large ash plumes into the atmosphere.
A black-and-white time-lapse video of Anak Krakatau shared by Volcano Discovery shows a dramatic night-time eruption lasting several minutes in which lava bombs can be seen launching out of the volcano and smoldering along its rim. An update shared on Tuesday noted that the volcano is “emitting lots of gas and steam” in small explosions and giving off a “near-constant glow” during the night. The volcano is still erupting as of Thursday and has since prompted a volcanic ash advisory. Satellite images shared by NASA Earth Observatory show the ash plume towering over the volcano’s peak.
“The location of the plume suggests that it is volcanic in origin,” said Verity Flower, a USRA volcanologist based at NASA’s Goddard Space Flight Center in a statement. Flower is using NASA’s Multi-angle Imaging Spectroradiometer (MISR) sensor on NASA’s Terra satellite to measure the distance the ash plumes travel, as well as to observe the shape, size, and light-emitting properties of particles held within the plume.
The color of the plume indicates that it is most likely composed of water vapor and gas, both of which are small reflective particles that give it its white, billowing appearance. By contrast, grey or brown plumes are made up of darker ash particles, one of which can be seen extending north in what appears to be lower in altitude than the whiter portion.
“It is possible the heavier ash particles emitted are staying lower in the atmosphere and are being transported to the north by near-surface winds,” said Flower. “In contrast, any water and gases within the plume, which are lighter, would be transported higher and would condense rapidly in the atmosphere.”
Indonesia’s Krakatau is responsible for some of the most devastating eruptions in recent history. Located near the Sunda Strait between Java and Sumatra, it has seen more than 50 known periods of eruptions in the last 2,000 years alone. The volcano most recently erupted in 2018, collapsing one of its flanks that set off a deadly tsunami, killing hundreds and emitting an ash plume that propelled into the stratosphere. Videos from the eruption showed footage of lava pouring over Anak Krakatau (Son of Krakatau), the most active region of the volcano, as well as ash plumes rising up to altitudes of 900-2,100 meters (3,000-7,000 feet) and lightning flashes appearing in a dramatic display of the powerful force of nature.
Indonesia’s Ministry of Energy and Mineral Resources said the volcano has seen increased activity within the last two weeks, though there is no increased risk of threat. Lava flows and ash rain have been reported within a 2-kilometer (1.2-mile) radius around the crater, but experts confirm the risk level remains at a two on a scale of four, with four being the highest.