abundant evidence for both ancient and active volcanism on

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Volcanoes in the Solar System
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What is the most pervasive geologic process?

• Many geologists would answer
• erosion
• plate tectonics
• Planetary geologists would tend to answer
• volcanism

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• Erosion by streams and oceans requires abundant
  liquid water
  
• Earth appears to be the only water planet
• In contrast volcanism seems to have played a part
  in the evolution of all the terrestrial planets
  and many of the moons in the solar system

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The Earths Moon

• The lunar seas on the Moon are actually great
  basins filled with basaltic lava flows
  
• Most erupted between 3-4 bya
• Lava flows must have been very fluid

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Moon - False Color Mosaic (Spacecraft Galileo)


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Mercury

• Mercury's surface is no longer active and remains
  the same as it has for millions of years

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Mercury (false color image JPL/NASA)
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Mars

• Extensive lava fields of what appear to be
  basaltic lava flows
  
• has some enormous shield volcanoes

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• Olympus Mons
• rises 25 km from base
• 600 km in diameter
• Los Angeles and its suburbs would fit within the
  80 km wide caldera
  
• hot spot?
• Last activity 200 mya

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Olympus Mons (Viking)
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Olympus Mons, Caldera
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Tharsis Montes (Viking orbiter)
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Venus

• Volcanic features include
• widespread lava plains, and extensive flows
• lava channels
• shield volcanoes
• cones, domes
• abundant evidence for both ancient and active
  volcanism on Venus

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• some volcanoes appear to be active however,
  clouds from volcanic erruptions are invisible to
  radar
  
• problem with observations - atmosphere of Venus
  is very thick and dense, 96 CO2
  
• Surface pressure 90X that of Earth
• majority of volcanic materials on Venus are
  thought to be basaltic in composition, partly
  because of their appearance, supported by
  evidence from Soviet probes

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Cluster of four overlapping domes is located on
the eastern edge of Alpha Regio
(Magellan Spacecraft)
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A volcano on the plains between Artemis Chasma
and Imdr Regio, Venus (Magellan)
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Recent flow, Venus (JPL, NASA image)
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Ammavaru Lava Flows, Venus (Magellan Spacecraft)
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Io

• Innermost Moon of Jupiter
• same size and mass as Earth
• may be the most volcanically active body in the
  solar system

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• Io's surface is covered with volcanic deposits
  that are thought to contain ordinary silicate
  rock
  
• various sulfur-rich compounds that give the
  satellite its distinctive color
  
• in some areas the surface is coated with frosts
  of sulfur dioxide
  
• dark areas are regions of current or recent
  volcanic activity
  

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Io (Spacecraft Voyager, Galileo)
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Ra Patera, Io (Voyager image)
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Europa

• Ice-rich surface of Europa suggests flows,
  possibly of ice, perhaps erupted onto the surface
  from the interior as viscous, glacier- like
  masses.
• Images do not show currently active ice volcanoes
  or geysers.
  

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Pwyll Crater, Europa
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Europa, flow structures