The Biggest Volcano on Jupiter's Moon Io Could Soon Erupt

Loki is the biggest volcano on the solar system's most volcanic object, Io.
Chris Young
Image of Io showing active plume of LokiNASA/JPL/USGS

Loki, a volcano on Jupiter's moon Io, may be about to erupt very soon. Loki is the biggest volcano on what is the most volcanic space object in our solar system. Observations over the last few decades have shown us that Loki erupts in a periodic cycle.

Based on previous observations, it is due to erupt over the next few days, and may have already started to erupt, scientists say.


Loki's cycle

After initial observations, Loki was discovered to have a cycle of around 540 days. This was based on observations made between 1988 and 2000, as described in a 2002 paper led by physicist and planetary scientist Julie Rathbun of the Planetary Science Institute.

Since 1988, there has been very little change in Loki's cycle. Until 2001, the observations showed that Loki would brighten for around 230 days before going dark again — the cycle would then repeat. Recently, Loki's cycle has been a bit shorter, at 475 days instead of 540.

"If this behavior remains the same, Loki should erupt in September 2019," Rathbun said in a press release by the Planetary Science Institute. "We correctly predicted that the last eruption would occur in May of 2018."

As Science Alert reports, Rathbun and her team see Loki as a lake of lava in a crater-like depression called a patera. This crater is approximately 200 kilometers (124 miles) wide.

The cycle seems to repeat when cooling crust on the surface of the lake becomes gravitationally unstable and collapses into itself. When this happens, the pool "overturns," and the cooling crust is replaced by fresh lava.

Eruption due any moment

Loki's last eruption occurred sometime in the period between May 23 and June 6, 2018. This means that the 475-day cycle restart window should fall between September 9 and 24. The eruption may have already started.

"Volcanoes are so difficult to predict because they are so complicated. Many things influence volcanic eruptions, including the rate of magma supply, the composition of the magma - particularly the presence of bubbles in the magma, the type of rock the volcano sits in, the fracture state of the rock, and many other issues," Rathbun said.

"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."

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