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Feb 6, 2022
Volcanism is characteristic of all planetary bodies of the terrestrial group - Mercury, Venus, Mars, Earth and the Moon. Currently, active volcanic activity has not been detected on any of these objects, except for the Earth.
There are a lot of volcanoes on the surface of Venus, but almost all of them are extinct. According to various sources, the total number of volcanic structures is more than 1600. Its surface consists of basalts of various types, similar to those that form at the bottom of the oceans on Earth.
The composition of the surface of Venus was determined during the landings of Soviet automatic stations. On March 1, 1982, the descent vehicle of the Venera-13 station made a soft landing on the surface of the second planet. Using an X-ray spectrometer, the composition of the rocks at the landing site was studied. As it turned out, the rocks in this place are leucite alkaline basalts, which are very numerous in the earth's crust.
Volcanic lava flows on Venus are much larger than their terrestrial counterparts and reach hundreds of kilometers in length and tens of kilometers in width. The spread of igneous material over such long distances is explained by the high temperature of the atmosphere, which slowed down the process of lava solidification.
Approximately 80% of the planet's surface is occupied by plains formed by lava flows, among which there are more than a hundred large stratovolcanoes (from Latin stratum - layer). It is a type of cone-shaped volcano, consisting of many hardened layers of lava and volcanic ash.
Other volcanic structures include volcanoes called "pancake domes". They are colloquially referred to simply as "pancakes". They form round domes with a diameter of up to 25 km and a height of no more than 700 m. Such volcanoes were formed as a result of eruptions of viscous lava rich in silica, unable to flow far from the source of the eruption.
A special place is occupied by structures that are called "arachnoids" (from the Greek - arachnid). These are large structures of volcanic origin found only on the surface of Venus. They look like concentric ovals connected by a network of faults, having some resemblance to a web, hence the name.
Exact confirmation of the presence of modern volcanic activity on Venus has not been found. But, according to some reports, there is reason to believe that Mount Maat - the second highest hill on Venus - erupted relatively recently. Its slopes are covered with fresh lava flows with no impact craters. Some researchers believe that the eruption of Mount Maat caused the strong fluctuations in the concentration of sulfur dioxide and methane in the atmosphere of Venus, discovered in the 1980s.
Source: Moscow Planetarium.
Related article:
Volcanism on Io
https://orbiterchspacenews.blogspot.com/2022/01/volcanism-on-io.html
Related links:
ROSCOSMOS Press Release: https://www.roscosmos.ru/34039/
Moscow Planetarium: https://www.roscosmos.ru/tag/moskovskiy-planetariy/
Astronomy: https://www.roscosmos.ru/tag/astronomija/
Venus: https://www.roscosmos.ru/tag/venera/
Images, Text, Credits: ROSCOSMOS/Moscow Planetarium/Orbiter.ch Aerospace/Roland Berga.
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