An oblique radar image of Sapas Mons, a volcano on Venus. This image was taken in 1993 by the Magellan mission that mapped the surface of Venus. The lighter colors on the image are younger lava flows from Sapas Mons, although how young is still an active debate. Image: NASA/JPL I'm back from a very successful stint at the SHRIMP lab. I'll be digesting the new data over the next few weeks as I work on a manuscript for all my Lassen Volcanic Field zircon information. I did want to briefly mention one article I ran across about volcanoes on Venus that is getting some attention in the media. A new article in Nature Geosciences by Marcq and others proposes that there are active eruptions occurring over the last few decades on the surface of Venus. Trying to see what is happening on the surface of Venus is next to impossible thanks to its thick atmosphere. However, observations of sulfur in the atmosphere by the Venus Express orbiter (and previous missions like Pioneer Venus) suggest that the amount of sulfur rises and falls dramatically by almost 100-fold -- a scenario most likely caused by a surface source injecting sulfur into the upper atmosphere. Of course, an excellent source of such sulfur injections is volcanism and we know that the surface of Venus is covered in young-looking volcanic features (however, the absolute age of these features is very unclear, from potentially recent to tens of millions of years old). So, although these changes in sulfur could be due to atmospheric fluctuations, the young surface of Venus does support the idea that active volcanism is present on the planet. We've also had some tantalizing indirect evidence that eruptions could be happening on Venus in recent years as well. I've always been fascinated by the strange "pancake" domes on Venus (see below). They look a lot like domes of silicic lavas here on Earth. However, most planetary scientists don't think these Venutian domes are silicic lavas (like rhyolite or dacite) but rather just viscous basaltic domes (maybe very crystal rich?) due to their lower aspect ratio than terrestrial silicic domes. Without surface reconnaissance, this question will be nearly impossible to resolve. Now, if only someone would build a Venus rover that could survive the harsh surface conditions so we can look for eruptions on the nearby planet.
The "pancake domes" of Alpha Regio on Venus as visualized in an overlay of Magellan radar images on Venus topography. These domes are ~25 km across and nearly 750 meters tall. Image: NASA/JPL
