NASA Confirms Thousands of Massive, Ancient Volcanic Eruptions On Mars (nasa.gov) 49
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One remaining question is how a planet can have only one type of volcano littering a region. On Earth volcanoes capable of super eruptions -- the most recent erupted 76,000 years ago in Sumatra, Indonesia -- are dispersed around the globe and exist in the same areas as other volcano types. Mars, too, has many other types of volcanoes, including the biggest volcano in the solar system called Olympus Mons. Olympus Mons is 100 times larger by volume than Earth's largest volcano of Mauna Loa in Hawaii, and is known as a "shield volcano," which drains lava down a gently sloping mountain. Arabia Terra so far has the only evidence of explosive volcanoes on Mars. It's possible that super-eruptive volcanoes were concentrated in regions on Earth but have been eroded physically and chemically or moved around the globe as continents shifted due to plate tectonics. These types of explosive volcanoes also could exist in regions of Jupiter's moon Io or could have been clustered on Venus. Whatever the case may be, Richardson hopes Arabia Terra will teach scientists something new about geological processes that help shape planets and moons.