spaceSpace and Physics

A Volcano On Jupiter’s Moon Io Is About To Erupt


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockSep 18 2019, 14:36 UTC

The characteristic U-shape of the Loki volcano on Io, as snapped from the Voyager 1 flyby. NASA 

We may not know how to predict volcanic eruptions on Earth but it turns out we are pretty good at predicting eruptions elsewhere in the universe. The Loki volcano on Io, Jupiter's innermost molten moon, is expected to erupt at any moment according to planetary scientists’ predictions.

The prediction that Loki is likely to erupt mid-September 2019 was presented this week at the European Planetary Science Congress & Division for Planetary Sciences of the American Astronomical Society Joint Meeting 2019 in Geneva by Dr Julie Rathbun of the Planetary Science Institute, who has been studying Loki for a long time.


In her 2002 paper, she showed that throughout the 1990s an eruption happened every 540 days, and using over two decades of observations she has continued to make predictions and studied how the periodicity stops and changes over time. Currently, it appears to erupt every 475 days.  

“Loki is the largest and most powerful volcano on Io, so bright in the infrared that we can detect it using telescopes on the Earth,” Dr Rathbun said in a statement. “If this behavior remains the same, Loki should erupt in September 2019, around the same time as the EPSC-DPS Joint Meeting 2019. We correctly predicted that the last eruption would occur in May of 2018.”

Rathbun suggests Loki is so predictable because of its size. Loki is a huge volcanic depression 202 kilometers (126 miles) across. It’s a lava lake covered by a thin solidified crust, which breaks apart once in a while. The extensive size is believed to make Loki less affected by the small but numerous complications that regular volcanos have.

“We think that Loki could be predictable because it is so large. Because of its size, basic physics are likely to dominate when it erupts, so the small complications that affect smaller volcanoes are likely to not affect Loki as much,” Rathbun said.


“However," she cautioned, "you have to be careful because Loki is named after a trickster god and the volcano has not been known to behave itself.  In the early 2000s, once the 540-day pattern was detected, Loki’s behavior changed and did not exhibit periodic behavior again until about 2013.”

Io is the most volcanically active place in the Solar System. Its internal heat is not the product of radioactive decay like on Earth but due to the tidal forces Jupiter and fellow moons Europa and Ganymede exert on Io.


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