Venus, often called Earth’s twin, possesses a surface almost entirely shaped by intense volcanic activity. Evidence for past eruptions covers most of the planet, and scientists now have compelling indications that this volcanism is ongoing in the present day. Detecting active eruptions is challenging due to Venus’s extreme environment, which includes crushing atmospheric pressure and surface temperatures hot enough to melt lead. Understanding the planet’s volcanism provides insight into how a world nearly identical to Earth in size and mass took such a dramatically different evolutionary path.
A Surface Shaped by Massive Eruptions
The surface of Venus appears remarkably young, a direct consequence of massive, planet-wide volcanic events. Analysis of impact craters shows the planet underwent a global resurfacing event approximately 300 to 600 million years ago. This event buried or modified almost all older craters, suggesting that vast quantities of lava quickly covered the entire globe.
Today, over 80% of the Venusian surface is covered by extensive volcanic plains, composed primarily of solidified basaltic lava flows. These flood lavas created sheets hundreds of kilometers wide, indicating eruptions on a scale rarely seen on Earth. The planet is also home to thousands of large shield volcanoes, often much larger than those in Hawaii. These structures, like Maat Mons, formed as magma repeatedly erupted from the same location, suggesting a geological process driven by internal mantle plumes rather than plate tectonics.
Detecting Current Volcanic Activity
Recent findings provide direct evidence of current eruptions, settling the decades-long debate about whether Venus is still volcanically active. The proof came from a re-examination of radar data collected by the Magellan spacecraft in the early 1990s. Scientists found that a volcanic vent on the north side of Maat Mons changed significantly between two images taken just eight months apart in 1991.
The vent, initially circular and about 2.2 square kilometers, had doubled in area and changed shape by the time the second image was taken. This change, along with new lava flows downhill from the vent, is interpreted as the result of an active eruption. Further analysis of the Magellan data in 2024 revealed that new rock, likely solidified lava, had formed at two other locations, Sif Mons and Niobe Planitia, during the mission’s two-year span. These observations suggest that volcanic activity on Venus may be comparable in frequency to Earth’s.
Beyond direct radar evidence, indirect observations also point toward a geologically active planet. Data from the Venus Express mission revealed transient thermal anomalies, or hotspots, on the surface that would brighten and fade over days. These temperature spikes, which reached several hundred degrees Fahrenheit, are best explained by fresh, hot lava flows that have not yet cooled. Additionally, scientists have detected sharp increases in the concentration of sulfur dioxide in Venus’s upper atmosphere. Since volcanic eruptions are a major source of sulfur gases, these temporary spikes are interpreted as evidence of large-scale volcanic degassing events.
The Strange Shapes of Venusian Volcanoes
Venus’s unique environment has resulted in volcanic structures unlike anything found on Earth. One of the most distinctive features is the “pancake dome,” a type of volcano known as farrum. These domes are characterized by steep sides, flat tops, and a remarkably circular outline.
Pancake domes are typically tens of kilometers in diameter and about one kilometer high, making them 10 to 100 times larger than volcanic domes on Earth. They are thought to form from highly viscous, possibly silica-rich lava slowly extruded under the immense surface pressure of Venus. The high viscosity caused the lava to pile up near the vent rather than flow far, resulting in the flat-topped, steep-sided shape.
Another structure unique to Venus is the corona, a large, circular feature surrounded by a ring of fractures. Coronae are volcano-tectonic formations, believed to be the surface expression of a mantle plume pushing the crust upward. The planet also features extraordinarily long, winding channels, known as canali, which stretch for thousands of kilometers across the plains. The extreme length and consistent width of these channels suggest they were carved by extremely low-viscosity lava flows, with some modeling proposing that carbonatite lavas, which flow much more easily than basalt, may be responsible.