Astronomers are unable to directly observe the surface of cloud shrouded Venus. With the advent of the space program however they can map the surface using radar. NASA's Magellan mission to Venus orbited the planet and made detailed radar maps of the surface. Understanding the geology of other planets, such as Venus, helps geologists understand Earth's geology.
Shield Volcanoes on Venus
Most volcanoes on Venus, like Martian volcanoes and many on Earth, are a type of volcano known as shield volcanoes, in which the lava flows upward through the volcano's center. They often form over a volcanic hotspot rather than tectonic plate boundaries.
Sif Mons and Gula Mons, examples of larger shield volcanoes on Venus, have peaks about 4 kilometers above the surrounding surface. They are smaller than Earth's largest shield volcano, Mauna Loa, which towers about 8 to 9 kilometers above the ocean floor.
If the top of a shield volcano collapses, it forms a type of crater known as a caldera. Calderas are common on Venus as well as Earth. The calderas formed by Sif Mons and Gula Mons are about 100 kilometers across. Venus also has many large meteorite impact craters as well as calderas.
Other Types of Volcanoes on Venus
Coronae, the largest volcanic features on Venus, are unique to Venus. (Don't be confused by the name; a corona on Venus is nothing like the Sun's corona.) Coronae are approximately circular and can measure a few hundred kilometers across. Aine, 300 kilometers across, is an example of a corona on Venus.
Lakshmi Planum, which is part of one of the continental features on Venus, Ishtar Terra, is a maximum of about 1500 kilometers across. It probably formed from a larger scale version of the same uplifting process that formed the coronae. Hot lava swells up from the mantle pushing the crust up.
Venus also has many lava dome, also called pancake dome, volcanoes. These volcanoes are circular, relatively flat, and much smaller than shield volcanoes. They are usually no larger than tens of kilometers in diameter.
Pancake domes formed when lava flowed out to the surface then flowed back. The crust that had solidified on the lava, however could not flow back and formed the pancake dome.
Volcanic Terrain
Volcanic activity includes lava flows and any other process that allows material to escape from Venus's interior, as well as erupting volcanoes. In addition to about 1600 large volcanoes and possibly hundreds of thousands of small volcanic features, about 80% of the planet's surface is covered with solidified lava flows.
Volcanic outgassing has released large amounts of carbon dioxide into the atmosphere of Venus. This carbon dioxide has produced a runaway greenhouse effect and a very harsh surface environment on Venus.
Astronomers do not know if Venus still has active volcanoes. They have found indirect evidence of volcanic eruptions, but the clouds obscure the surface too much to directly see a volcano erupting on Venus. Venus has however had considerable volcanic activity in its geologic history. Detailed study of the volcanoes on Venus tell planetary astronomers and geophysicists that the tectonic processes on Venus are much different than plate tectonics on Earth.
Author Twinkle Brar
Shield Volcanoes on Venus
Most volcanoes on Venus, like Martian volcanoes and many on Earth, are a type of volcano known as shield volcanoes, in which the lava flows upward through the volcano's center. They often form over a volcanic hotspot rather than tectonic plate boundaries.
Sif Mons and Gula Mons, examples of larger shield volcanoes on Venus, have peaks about 4 kilometers above the surrounding surface. They are smaller than Earth's largest shield volcano, Mauna Loa, which towers about 8 to 9 kilometers above the ocean floor.
If the top of a shield volcano collapses, it forms a type of crater known as a caldera. Calderas are common on Venus as well as Earth. The calderas formed by Sif Mons and Gula Mons are about 100 kilometers across. Venus also has many large meteorite impact craters as well as calderas.
Other Types of Volcanoes on Venus
Coronae, the largest volcanic features on Venus, are unique to Venus. (Don't be confused by the name; a corona on Venus is nothing like the Sun's corona.) Coronae are approximately circular and can measure a few hundred kilometers across. Aine, 300 kilometers across, is an example of a corona on Venus.
Lakshmi Planum, which is part of one of the continental features on Venus, Ishtar Terra, is a maximum of about 1500 kilometers across. It probably formed from a larger scale version of the same uplifting process that formed the coronae. Hot lava swells up from the mantle pushing the crust up.
Venus also has many lava dome, also called pancake dome, volcanoes. These volcanoes are circular, relatively flat, and much smaller than shield volcanoes. They are usually no larger than tens of kilometers in diameter.
Pancake domes formed when lava flowed out to the surface then flowed back. The crust that had solidified on the lava, however could not flow back and formed the pancake dome.
Volcanic Terrain
Volcanic activity includes lava flows and any other process that allows material to escape from Venus's interior, as well as erupting volcanoes. In addition to about 1600 large volcanoes and possibly hundreds of thousands of small volcanic features, about 80% of the planet's surface is covered with solidified lava flows.
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Volcanic outgassing has released large amounts of carbon dioxide into the atmosphere of Venus. This carbon dioxide has produced a runaway greenhouse effect and a very harsh surface environment on Venus.
Astronomers do not know if Venus still has active volcanoes. They have found indirect evidence of volcanic eruptions, but the clouds obscure the surface too much to directly see a volcano erupting on Venus. Venus has however had considerable volcanic activity in its geologic history. Detailed study of the volcanoes on Venus tell planetary astronomers and geophysicists that the tectonic processes on Venus are much different than plate tectonics on Earth.
Author Twinkle Brar
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