Best Evidence Yet That Venus Is Still Geologically Active

The varying topography of coronae (volcanic structures) on Venus, can reveal recent geologic activity. The black line represents a gap in data. Laurent Montési/ University of Maryland

Katy Pallister 21 Jul 2020, 13:11

Question marks have plagued Venus for a while over its potential to still be an active planet. However, using a new 3D model of volcanic structures on Venus, researchers have identified 37 recently active sites, providing the best evidence yet of geological activity on our hostile neighbor.

“Our study provides new evidence for widespread recent tectonic and magmatic activity on the surface of Venus,” lead author Anna Gülcher of ETH Zürich, Switzerland, told IFLScience.

“We show that even today, there is a fair number of places on Venus (at least 37) where hot currents from the interior, called plumes, are able to traverse the lithosphere (the cold and strong outermost layer of a planet), trigger volcanic and tectonic activity to form the geological structures called coronae,” Gülcher continued.

Meaning “crown” in Latin, we have recently become familiar with the term “corona” in a public health setting. But on Venus, coronae are large (tens to hundreds of kilometers wide) ring-shaped structures characterized by a round central region and surrounding circular cracks.

“These structures do not exist on Earth, which makes these structures even more intriguing,” Gülcher said. “The round shape and the huge size of coronae suggests that they are formed above rising mantle plumes (conduits of hot rock ascending to the surface) from greater depths within the planet.”

To investigate the varying topology of coronae, Gülcher and her colleagues ran 3D simulations that modeled how varying sub-surface behavior would manifest itself in corona structures. They discovered that “active” coronae had an elevated dome surrounded by a trench, whereas inactive coronae had the complete inverse (a concave center bounded by an elevated rim).

Armed with these descriptors, Gülcher and the team then assessed the topographic patterns of 133 large coronae on Venus, to determine whether any of the structures indicated internal activity. In total, 37 coronae were consistent with ongoing plume activity. However, they were not evenly distributed across the planet’s surface.

“What is most interesting in the “active” coronae is that most are found in a handful of locations: a cluster in what we call Eistla Regio, and in essentially a circle making a ring around the planet in the southern hemisphere,” Gülcher explained. “We do not know why there is this distribution, but it might reflect the circulation patterns of the deeper interior.”

Published in Nature Geoscience, Gülcher produced an accompanying first-of-its-kind global map (below) of recent plume activity on Venus, for the study. Going forward this will help scientists to identify regions of interest for future geologic instruments sent to Venus. As Gülcher said, “Venus is clearly not ‘geologically dead’.”

In the global map of Venus above, active coronae appear in red and inactive coronae appear in white. Anna Gülcher

 

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