The surface of Venus has many volcanoes, but until now no evidence of recent volcanic activity has been found, however a new analysis of data taken three decades ago offers strong evidence of a volcano eruption.
A study by the University of Alaska (USA) led by Robert Herrick revealed the existence of a vent in the Maat Mons volcano of about 2.2 square kilometers that changed shape and grew for eight months in 1991, which for the team points to ongoing volcanic activity.
Such changes are associated on Earth with volcanic activity, either from an eruption at the vent or from the movement of magma beneath the vent, causing the vent walls to collapse and expand.
The images used for the research were taken by NASA’s Magellan space probe, which arrived at Venus on August 10, 1990 and during its mission made almost a thousand images, which with new technologies have been able to be analyzed once again.
During his mission, Magellan used radar to image the surface of Venus from different orbits, observing some locations two or three times over the course of two years, including areas later identified as possible sites of volcanic activity.
The team focused on a region of Venus that is home to two of the largest volcanoes on the planet, Ozza and Maat Mons, also comparable in volume to the largest on Earth, but with lower slopes, so they are more widespread.
Herrick compared an image from mid-February 1991 with one from mid-October of that year and observed a change in a vent on the north side, from a circular formation of about 2.2 square kilometers to an irregular shape. of approximately 4 square kilometers.
The second image also indicated that the chimney walls had been made shorter, perhaps only a few hundred meters high, and that the chimney was nearly filled to the brim.
The researchers speculate that a lava lake formed at the vent during the eight months between images, though whether the contents were liquid or had cooled and solidified is unknown.
The changes in the walls of the vent could also respond to a non-volcanic collapse, but caused by an earthquake that would have caused the changes.
However, the team notes that collapses of this magnitude in Earth’s volcanoes have always been accompanied by nearby volcanic eruptions; the magma is withdrawn from under the chimney because it is going to another place.
Venus’ surface is geologically young, and estimates of how often eruptions could occur have been speculative, ranging from several large eruptions a year, to every several or even every tens of years, Herrick noted. The researcher said that it can now “affirm that Venus is volcanically active, in the sense that there are at least a few eruptions a year.”
Therefore, he considered that it could be expected that “the next missions to Venus will observe new volcanic flows that have occurred since the Magellan mission ended three decades ago, and we should observe some activity while the next two orbital missions collect images.”
