Venus appears to be volcanically active, according to a new paper that provides strong clues to answer the long-standing question of whether sister planet Earth currently has eruptions and lava flows.
Venus, though similar to Earth in size and mass, differs markedly in that it does not have plate tectonics. The boundaries of Earth’s moving plates are the primary sites of volcanic activity.
New research by University of Alaska Fairbanks Research Institute for Geophysics Professor Robert Herrick uncovers a roughly square-mile volcanic vent that changed shape and grew over a period of eight months in 1991. Changes on this scale on Earth are associated with volcanic activity, both through a volcanic eruption and In the vent or the movement of magma below the vent causing the collapse of the vent walls and expansion of the vent.
The research was published today in the journal Sciences.
Herrick studied images taken in the early 1990s during the first two imaging sessions of NASA’s Magellan space probe. Until recently, comparing digital images to find new lava flows was time-consuming, the paper notes. As a result, a few scientists have delved into the Magellan data to form the features.
“Only in the past decade or so has Magellan data been available at full resolution, distributed and easily manipulated by an investigator with a typical personal workstation,” Herrick said.
The new research focused on a region containing two of Venus’ largest volcanoes, Oza and Maat Mons.
“Uzza and Maat Mons are comparable in size to Earth’s largest volcanoes, but they have lower slopes and therefore are more spread out,” Herrick said.
Ma’at Mons has an enlarged vent which indicates volcanic activity.
Herrick compared the image of Magellan from mid-February 1991 with the mid-October 1991 image and noted a change in the vent on the north side of the domed shield volcano which is part of the Maat Mons volcano.
The opening has grown from a circular formation of just under 1 square mile to an irregular shape of about 1.5 square miles.
The later image indicates that the walls of the vent became shorter, perhaps only a few hundred feet high, and that the vent was filled almost to its rim. The researchers speculate that a lava lake formed in the vent during the eight months between images, though it is not known whether the contents were liquid or cooled and solidified.
The researchers offer one caveat: Non-volcanic collapse of the vent walls caused by the earthquake may have caused the expansion. But they observed that the collapse of vents of this magnitude on Earth’s volcanoes was always accompanied by nearby eruptions; Magma is withdrawing from the bottom of the vent because it is going elsewhere.
Geologically, the surface of Venus is small, Herrick said, especially compared to all other rocky bodies except Earth and Jupiter’s moon Io.
“However, estimates of how often volcanic eruptions might occur on Venus have been speculative, and range from several large eruptions every year to one such eruption every several or even decades,” he said.
Herrick compares the lack of information about volcanic activity on Venus with what is known about Jupiter’s moon Io and Mars.
“Io is so active that many continuous eruptions are filmed every time we observe it,” he said.
On a geological time scale, Herrick said, relatively small lava flows indicate that Mars is still volcanically active.
“However, nothing has happened in the 45 years that we’ve been observing Mars, and most scientists would say you’d probably need to observe the surface for a few million years to have a reasonable chance of seeing new lava flows,” he said.
Herrick’s research adds Venus to a small group of volcanically active objects in our solar system.
“We can now say that Venus is currently volcanically active, meaning that there are at least some volcanic eruptions every year,” he said. “We can expect the upcoming Venus missions to monitor new volcanic flows that have occurred since the Magellan mission ended three decades ago, and we should see some activity occur as the two prospective orbital missions collect images.”
Co-author Scott Hensley of NASA’s Jet Propulsion Laboratory conducted the modeling research.
