Venus is the second planet from the sun. Credit: NASA
The ETH researchers used computer simulations to classify the current activity of corona structures on the surface of Venus. To their surprise, they found a previously unknown ring of fire on our neighboring planet.
Years ago, planetary researchers discovered unusual circular structures on the surface of Venus by looking at high-resolution images of POTMagellan’s mission. These structures are known as crowns (from the Latin meaning “crowns”; singular: crown). A few years ago, a team of ETH researchers led by Taras Gerya, a professor of geophysics in the Department of Earth Sciences, used computer models to investigate how these structures were formed.
Most of the researchers assume that these strange circular surface features are made of mantle feathers from the depths of the planet.
The circular mountain in the foreground is a 500 kilometer crown in the Galindo region of Venus. Dark rectangles are an artifact. Credit: NASA / JPL / USGS
A mantle plume is a stream of hot molten rock that is carried by convection currents from the lower mantle to the crust in a mushroom-shaped column at the top. The heat it carries melts the surface of the crust in a circular fashion. Continuous material rising from greater depths widens the head of the plume and expands the ring structure on the surface to form a crown. The solid crust that surrounds the mantle plume may crack and eventually sink below the crown edge, triggering local tectonic processes.
Computer simulations of crown structural variations
However, the topography of the crowns is neither homogeneous nor easy to describe. “These structures exist in a wide variety of shapes and dimensions on the surface of Venus,” says Anna Gülcher, a doctoral student in Gerya’s research group.
Following this observation, Gülcher used a larger set of enhanced 3D simulations to reexamine the crowns while seeking to establish a link between the variation in surface topography and the processes at work below. Their study was recently published in the journal. Nature Geoscience is a monthly peer-reviewed scientific journal published by the Nature Publishing Group that covers all aspects of Earth science, including theoretical research, modeling, and fieldwork. Other related work is also published in fields including atmospheric science, geology, geophysics, climatology, oceanography, paleontology, and space science. It was established in January 2008.
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The new simulations show that the topography of a corona depends on the thickness and strength of the crust where the mantle feather strikes it, and, above all, that its topographies are directly related to the activity of the magma column below the surface.
Venus’s ring of fire. On the global Venus map above, active crowns appear in red and inactive crowns appear in white. Credit: Anna Gülcher
However, it is important to note that the position and dynamics of Earth’s ring of fire are the result of plate tectonics, he explains. On Venus, the cause is vertical access point volcanism, a phenomenon that occurs in only a few places on Earth, such as below the Hawaiian Islands.
Exactly why the mantle feathers on Venus are arranged in such a belt, and what this means for deep internal processes on Venus, is an important question to be addressed in future studies, says Gülcher. This can be done with large-scale computer simulations.
High computing capacity is required
In their models, the researchers simulate only the first few hundred kilometers of the mantle plume. However, in reality, the plume ducts could be more than 1,000 kilometers long: “Simulating the total length that the plumes could reach is out of the question due to the enormous computing power it would require,” says Gülcher. The current simulations, carried out with the Euler cluster at ETH, are already eight times larger than the previous ones.
Reconstruction of the surface of Venus based on photographs taken by the Magellan space probe. Credit: NASA
Planetary scientists hope their findings will also provide new insights into how mantle feathers work below Earth’s surface. They are likely to be the causes of hot spot volcanism, as seen on the Hawaiian Islands. Mantle feathers may have been a trigger for the plate tectonics observed on Earth as well, as the Gerya research group could also simulate. As mentioned at the time, Venus could serve as a model for processes that may have taken place in Earth’s early history.
Active feathers form a ring of fire around Venus
This outstanding observation allowed Gülcher and his colleagues to classify more than a hundred great crowns on Venus into two main groups: those that have been formed on an active column that currently rises and transports molten material, and those that are on a column that It has cooled and become inactive. “Each crown structure has a specific signature that indicates what is happening underneath it,” says Gülcher.
This image is a composite of data from NASA’s Magellan spacecraft and Pioneer Venus Orbiter. Credit: NASA / JPL-Caltech
On a map of Venus, he plotted all the crowns according to how their activity was classified. To her surprise, most of the crowns that cover the active feathers of the mantle form a belt in the southern hemisphere of Venus. Only a handful of active feathers are outside this band. “We call this band the ‘Ring of Fire’ on Venus in reference to the ‘Ring of Fire’ on Earth,” says Gülcher. She assumes that the belt matches an area that expels high levels of rising feather material.
For more information on this research, read Scientists Identify 37 Active Volcanoes on Venus.
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Reference: “Crown structures powered by plume-lithosphere interactions and evidence of continuous plume activity on Venus” by Anna JP Gülcher, Taras V. Gerya, Laurent GJ Montési and Jessica Munch, July 20, 2020, Nature Geoscience.
DOI: 10.1038 / s41561-020-0606-1
