SHIELD

VOLCANOES

created by R. Mason  Geol 1100  The Richard Stockton College of NJ


Shield volcanoes are a type of volcano given their name for their broad gently sloping profile which looks like a warrior's shield.  They are composed of thousands of fluid lava flows that spread great distances, sometimes greater than 50 kilometers.  The tallest volcano in the world is a shield volcano.  Mauna Kea Volcano rises 13,798 feet above sea level but extends about 19,700 feet to the ocean floor, for a grand total of 33,500 feet above sea level, dwarfing the world's tallest mountain, Everest, by over 4,000 feet!  Mauna Loa, located on the island of Hawaii, has a height of 28,000 ft, but it has a much greater volume than Mauna Kea.  It holds an estimated 80,000 km3 of basalt!

Shield volcanoes are also some of the world's most active.  Kilauea, also on the island of Hawaii, began erupting in January of 1983, and still shows no signs of abating.


 

The photo to the left shows the eruption

of Kilauea.  Notice the pahoehoe and

 aa lava flows typical of shield volcano 

eruptions.  There is little pyroclastic

debris.  This is why shield volcanoes are

said to have silent eruptions.

 


 

Shield volcanoes can erupt

through central vents, or the lava

can pour out from long fissures,

creating broad plateaus.  One

example is the Columbia River

Plateau in the states of Washing-

ton and Oregon, whose lava flows

can measure more than a mile

deep.

   


 

One reason why the lava from shield volcanoes

can cover such great distances before cooling is

due to lava tubes.  Lava tubes are formed

during long lived eruptions when the surface of

a lava flow begins to stick to the sides of its

channel.  When it sticks it cools.  Over a period

of time the entire surface of the lava flow will

be cooled.  The crust will now insulate the lava

inside of it, allowing it to flow for several more

miles.

 


 

Some interesting shield volcano facts?

Shield volcano pics?