Earth
This map shows to location of earthquakes around the Pacific Ocean - the
"Ring of Fire".
Click on image for full size version (104K GIF)
Image from: The U.S. Geological Survey
The image above shows the locations of earthquake epicenters for
earthquakes with magnitudes greater than 5, from 1980 through 1990.
If you look at the large version of this image, you can see that
earthquakes tend to occur along crustal plate boundaries - as do many
volcanoes. On Earth, groups of volcanoes form together in strings, like
pearls in a necklace. Some of these form strings of islands, like the Aleutian
Islands in Alaska, shown bending in a graceful arc in this picture. Other
strings of volcanoes form within a mountain ranges, like the Cascade range
along the western coast of the United States. The Pacific Ocean is
surrounded by areas of high earthquake activity and numerous volcanoes,
from Asia through South America. This forms the famous "Ring of Fire".
The Hawaiian Islands, in the central Pacific, are not located at a
crustal boundary, and are formed by a long-lived hot spot in the Earth's
crust. Notice the numerous earthquakes that occur along the Atlantic
Ocean mid-ocean ridge, where new crust is formed from undersea volcanoes.
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Mars
A color map of the altitude of the surface of Mars (red high, blue low),
showing where volcanoes are located.
Click on image for full size version (163K GIF)
Image from: NASA
On Mars, the Tharsis Ridge is the home of several volcanoes, including
Olympus Mons. The volcanoes are the yellow and red dots in the sea
of blue in this image. Olympus Mons is the leftmost volcano in the
image. The three large volcanoes which accompany Olympus Mons on the Tharsis
Ridge are Arsia Mons, Pavonis Mons, and Ascraeus Mons. Other volcanoes
named Tharsis Tholus, Ceraunius Tholus, Elysium Mons, and Albov
Tholus are found in the right-hand side of the full resolution version of the
map above (click on the image to bring it up).
On this map of Mars, the lightly cratered Tharsis Ridge can be seen, as
well as the heavily cratered Martian highlands (near the bottom of the
picture), and Valles Marineris to the right.
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