Will Loki, a massive volcano on Jupiter’s Io moon, erupt as predicted?

Io is the fourth-largest moon in the solar system and is the innermost of the four Galilean moons of Jupiter.

Io is also the most volcanically active active bodies in the Milky Way, and it appears ready to live up to that billing again very soon, according to EarthSky:

“Jupiter’s moon Io is a world of active volcanoes, and Loki Patera is the largest of these, a great depression in the moon’s surface some 126 miles (202 km) across. An active lava lake resides in this depression, and the molten lava there is thought to be directly connected to a magma reservoir below. Above, the lake is likely covered over by a thin, solidified crust. Scientists peering through earthly telescopes have seen this area as continuously active. They think that the crust overlying the lake occasionally gives way, causing a brightness increase. In fact, Loki’s periodic eruptions are so regular that an astronomer has predicted one for this month.”

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A diagram showing the volcanic interior of Io (Via Wikimedia Commons)

The prediction was made by Julie Rathbun, a senior scientist at the Planetary Science Institute in Tucson, Arizona, who noted:

“If this behavior remains the same, Loki should erupt in September 2019, around the same time as the EPSC-DPS meeting in Geneva. We correctly predicted that the last eruption would occur in May of 2018.”

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Io is miniscule when compared to Jupiter (Via Wikimedia Commons)
Loki the Predictable


Astronomers have made accurate predictions regarding volcanic eruptions on Io because of its structure and the frequency of major volcanic activity on the moon:

“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 volcanoes have.”

Rathbun says that Loki has become one of the constants in the galaxy when it comes to volcanic eruptions:

“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.”

A volcanic eruption on Io as seen from space (Via JPL/NASA)
Angry Io


While Io is indeed known for volcanic activity, its internal heat is not due to radioactive decay the way Earth is. Instead, Io is pocked with giant magma deposits as a result of tidal forces from Jupiter and its sister moons Europa and Ganymede. Those three exert tremendous pressure on Io and help create conditions that are idea for the formation of volcanoes.

As The Planets notes, Io was first discovered by Galileo in the 17th century:

“Galileo Galilei discovered Io on January 8th, 1610 and the discovery, along with the three other Jovian moons Europa, Ganymede and Callisto, were the first moons discovered that were orbiting a planet other than Earth. Technically, Galileo discovered Io the night before, but he wasn’t able to distinguish between Io and Europa until the following night. The discovery of Io and the Galilean moons led to the understanding that planets orbit around the Sun – and that Earth was not the center of our solar system.”

There are more than 400 active volcanoes on Io:

“Volcanic plumes can rise 300 km (190 miles) above the surface. This was originally discovered by NASA’s Voyager 1 mission in 1979. The reason for this volcanic activity is the tidal heating which happens as Io is stretched and squeezed while it orbits Jupiter. This tidal bulge also shifts Io’s surface up by as much as 100 m throughout it’s orbit.”

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NASA describes IO as “A giant pizza covered with melted cheese and splotches of tomato and ripe olives” (Via Marc Van Norden/Flickr)

A word of warning when it comes to the pending eruption on Io, and it comes from the same person who made the prediction of a September event, Dr. Rathbun:

“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.”

All we can do now is watch and wait.


For more on Io’s volcanic activity, watch this video:


Featured Image Via NASA


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