geologyMcAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams

Home » Volcanoes » Volcanoes on Venus


Volcanoes on Venus



Discovery of a Volcanic Landscape



Venus is the closest planet to Earth. However, the surface of Venus is obscured by several layers of thick cloud cover. These clouds are so thick and so persistent that optical telescope observations from Earth are unable to produce clear images of the planet's surface features.

The first detailed information about the surface of Venus was obtained until the early 1990s when the Magellan spacecraft (also known as the Venus Radar Mapper) used radar imaging to produce detailed topography data for most of the planet's surface. That data was used to create images of Venus such as the one shown at the top of the right column.

Researchers expected the topography data to reveal volcanic features on Venus but they were surprised to learn that at least 90% of the planet's surface was covered by lava flows and broad shield volcanoes. They were also surprised that these volcanic features on Venus were enormous in size when compared to similar features on Earth.


Enormous Shield Volcanoes



The Hawaiian Islands are often used as examples of large shield volcanoes on Earth. These volcanoes are on the order of 120 kilometers wide at the base and about 8 kilometers in height. They would be among the tallest volcanoes on Venus; however, they would not be competitive in width. Large shield volcanoes on Venus are an impressive 700 kilometers wide at the base but are only about 5.5 kilometers in height.

Olympus Mons: The Largest Shield Volcano on Mars


In summary, the large shield volcanoes on Venus are several times as wide as those on Earth and they have a much gentler slope. A relative size comparison of volcanoes on the two planets is given in the graphic below - which has a vertical exaggeration of about 25x.

shield volcano sizes Venus vs Earth
This graphic compares the geometry of a large shield volcano from Venus with a large shield volcano from Earth. Shield volcanoes on Venus are usually very broad at the base and have gentler slopes than the shield volcanoes found on Earth. VE=~25


Extensive Lava Flows



Lava flows on Venus are thought to be composed of rocks that are similar to the basalts found on earth. Many of the lava flows on Venus have lengths of several hundred kilometers. The lava's mobility might be enhanced by the planet's average surface temperature of about 470 degrees Celsius.

The image of Sapas Mons volcano, in the right column of this page, contains many excellent examples of long lava flows on Venus. The radial appearance of the volcano is produced by long lava flows extending from the two vents at the peak and from numerous flank eruptions.


Pancake Domes



Venus has a large number of features that have been called "pancake domes". These are similar to lava domes found on Earth, but on Venus they are up to 100 times as large. Pancake domes are very broad, with a very flat top and are usually less than 1000 meters in height. They are thought to form by the extrusion of viscous lava.

pancake domes on Venus
Radar image of three pancake domes on the left and a geologic map of the same area on the right. Anyone interested in learning about the surface features of Venus can obtain radar images from NASA and compare them with geologic maps prepared by USGS.


When Did the Volcanoes on Venus Form?



Most of the surface of Venus is covered by lava flows that have a very low impact cratering density. This low impact density reveals that the planets surface is mostly less than 500,000,000 years old. Volcanic activity on Venus can not be detected from Earth but enhanced radar imaging from the Magellan spacecraft suggest that volcanic activity on Venus still occurs. (see image below)

evidence of recent volcanic activity
Radar images of Idunn Mons Volcano in the Imdr Regio region of Venus. The image on the left is a radar topography image with a vertical exaggeration of about 30x. The image on the right is color-enhanced based upon thermal imaging spectrometer data. The red areas are warmer and thought to be evidence of recent lava flows. Image by NASA.


Other Processes that Shape the Surface of Venus



IMPACT CRATERING

Asteroid impacts have produced many craters on the surface of Venus. Although these features are numerous they do not cover more than a few percent of the planet's surface. The resurfacing of Venus with lava flows that is thought to have occurred about 500,000,000 years ago took place after impact cratering of planets in our solar system had fallen to a very low level.

Map of Earth's Asteroid Impacts


EROSION AND SEDIMENTATION

The surface temperature of Venus is about 470 degrees Celsius -- much too high for liquid water. Without water, stream erosion and sedimentation are unable to make significant modifications to the surface of the planet. The only erosional features observed on the planet have been attributed to flowing lava.


WIND EROSION AND DUNE FORMATION

Blood Diamonds
What Causes a Tsunami?
Marcellus Shale
Rare Earth Elements
The atmosphere of Venus is thought to be about 90 times as dense as Earth's. Although this limits wind activity some dune-shaped features have been identified on Venus. However, the available images do not show wind-modified landscapes covering a significant portion of the planet's surface.


PLATE TECTONICS

Plate tectonic activity on Venus has not been clearly identified. Plate boundaries have not been recognized. Radar images and geologic maps produced for the planet do not show linear volcano chains, spreading ridges, subduction zones and transform faults that provide evidence of plate tectonics on Earth.


Summary



Volcanic activity is the dominant process for shaping the landscape of Venus with over 90% of the planet's surface being covered by lava flows and shield volcanoes. The shield volcanoes and lava flows on Venus are very large in size when compared to similar features on Earth.


Contributor:




Find it on Geology.com




More from Geology.com


Homeowners Insurance
Homeowners Insurance usually does not cover the most common geologic hazards.
US Diamond Mines
US Diamond Mines: Did you know that diamonds can be found in the United States?
Sliding Rocks
Sliding Rocks Mystery: What causes these rocks to slide across a Death Valley playa?
Diamonds from Coal
Biggest Misconception: Lots of people think that diamonds form from coal. Not True!
caldera
Calderas are enormous volcanic craters formed by some of Earth\'s largest eruptions.
city satellite images
What City is This? Can you recognize United States cities from satellite images?
Volcanoes
Volcanoes: Articles about volcanoes, volcanic hazards and eruptions past and present.
Fossils
Fossils: Learn about fossils and fossil discoveries around the world.




volcanoes on Venus
A simulated color image of the surface of Venus created by NASA using radar topography data acquired by the Magellan spacecraft. Enlarged views at 900 x 900 pixels or 4000 x 4000 pixels.




Sapas Mons Volcano
A simulated color image of Sapas Mons volcano, located on the Atla Regio rise near the equator of Venus. The volcano is about 400 kilometers across and about 1.5 kilometers high. The radial appearance of the volcano at this scale is caused by hundreds of overlapping lava flows - some originating from one of the two summit vents but most originating from flank eruptions. Image created by NASA using radar topography data acquired by the Magellan spacecraft. Enlarged views at 900 x 900 pixels or 3000 x 3000 pixels.


Sapas Mons Volcano
An oblique view of Sapas Mons volcano, the same volcano shown in the vertical view above. This image views the volcano from the northwest. Features visible in this image can easily be matched to the vertical view above. Lava flows several hundred kilometers in length appear as narrow channels on the flanks of the volcano and spread into broad flows on the plain that surrounds the volcano. Image by NASA. Enlarge image.


three volcanos in color topography
USGS has produced detailed geologic maps for many areas of Venus. These maps have descriptions and correlation charts for the mapped units. They also include symbols for faults, lineaments, domes, craters, lava flow directions, ridges, grabens and many other features. These can be paired with NASA radar images to learn about volcanoes and other surface features of Venus.


Information for Volcanoes on Venus
[1] NASA Image Gallery of Venus, a searchable collection of images that can be downloaded, NASA, accessed January 2013.

[2] USGS Geologic Maps of Venus, a collection of maps in .pdf format, USGS, accessed January 2013.

[3] Volcano Sapas Mons, images and information about the volcano from the Magellan spacecraft program, NASA, 1996.

[4] Venus Global View, computer simulated global view of Venus from the Magellan spacecraft program, NASA, 1996.

[5] NASA-Funded Research Suggests Venus is Geologically Alive, article about recent volcanism on Venus, NASA, 2010.

[6] Volcanoes on Venus, overview article from the Volcano World collection, Oregon State University, 2005.


Rock Type Photo Gallery
Types of Volcanic Eruptions
Mount Rainier Volcanic Hazards
East Africa Rift
Teaching Plate Tectonics with Drawings
Volcanoes!
Vesuvius
Marcellus Shale



© 2005-2014 Geology.com. All Rights Reserved.
Images, code and content of this website are property of Geology.com. Use without permission is prohibited. Pages on this site are protected by Copyscape.