Venus is similar to Earth in size and mass but does not have plate tectonics, which are the primary locations of volcanic activity. A lingering question has always been if there is volcanic activity anyway.
A new paper says it has eruptions and lava flows; the evidence is a nearly one-square-mile volcanic vent in an area containing two of Venus’ largest volcanoes, Ozza and Maat Mons, that changed in shape and grew over eight months in 1991. Changes on such a scale on Earth are associated with volcanic activity, whether through an eruption at the vent or movement of magma beneath the vent that causes the vent walls to collapse and the vent to expand.
The images were from the first two imaging cycles of NASA’s Magellan space probe. Comparing digital images in full resolution to find new lava flows took too much computation time in the past but now a desktop can do it.
Maat Mons contains the expanded vent that indicates volcanic activity. University of Alaska Fairbanks Professor Robert Herrick compared a Magellan image from mid-February 1991 with a mid-October 1991 image and noticed a change to a vent on the north side of a domed shield volcano that is part of the Maat Mons volcano.
The vent had 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 vent’s walls became shorter, perhaps only a few hundred feet high, and that the vent was nearly filled to its rim. The researchers speculate that a lava lake formed in the vent during the eight months between the images, though whether the contents were liquid or cooled and solidified isn’t known.
The researchers offer one caveat: a nonvolcanic, earthquake-triggered collapse of the vent’s walls might have caused the expansion. They note, however, that vent collapses of this scale on Earth’s volcanoes have always been accompanied by nearby volcanic eruptions; magma withdraws from beneath the vent because it is going somewhere else.
The surface of Venus is geologically young, especially compared to all the other rocky bodies except Earth and Jupiter's moon Io, Herrick said.
“However, the estimates of how often eruptions might occur on Venus have been speculative, ranging from several large eruptions per year to one such eruption every several or even tens of years,” he said.
Herrick contrasts the lack of information about Venusian volcanism with what is known about Jupiter’s moon Io and about Mars.
“Io is so active that multiple ongoing eruptions have been imaged every time we've observed it,” he said.
On a geological time scale, relatively young lava flows indicate Mars remains volcanically active, Herrick said.
“However, nothing has occurred in the 45 years that we have been observing Mars, and most scientists would say that you'd probably need to watch the surface for a few million years to have a reasonable chance of seeing a new lava flow,” he said.
Herrick’s research adds Venus to the small pool of volcanically active bodies in our solar system.
“We can now say that Venus is presently volcanically active in the sense that there are at least a few eruptions per year,” he said. “We can expect that the upcoming Venus missions will observe new volcanic flows that have occurred since the Magellan mission ended three decades ago, and we should see some activity occurring while the two upcoming orbital missions are collecting images.”
Even Without Plate Tectonics, Venus Is Volcanically Active
By News Staff | March 15th 2023 11:14 AM | Print | E-mail