Hot Spot Volcanism All of the mountains in this map of the floor of the Pacific Ocean are volcanoes Note that there are several long chains of volcanoes But there are also many individual volcanoes None of these volcanoes are formed along plate boundaries
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Hot Spot Volcanism All of the mountains in this map of the floor of the Pacific Ocean are volcanoes Note that there are several long chains of volcanoes.
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Hot Spot VolcanismAll of the mountains in this map of the floor of the Pacific Ocean are volcanoes
Note that there are several long chains of volcanoes
But there are also many individual volcanoes
None of these volcanoes are formed along plate boundaries
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Hot Spot Volcanism
These isolated areas of volcanic activity are not associated with plate boundaries
These volcanoes are found both on continents and out in the ocean
Hot Spot Volcanism
A plume of hot mantle material rises up to the bottom of the lithosphere
Melting occurs and magma is created
These are called “hot spots”
They can last for many millions of years
Hot Spot Volcanism
The magma works its way to the surface over the hot spot and a volcano is formed
Out in the ocean, the volcano may or may not reach the surface and form an island
In fact, few oceanic volcanoes reach the surface
Hot Spot Volcanism
As the moving plate carries the volcano away from the hot spot, the volcano dies out
With time, another volcano may form
This cycle may repeat many times, forming a long chain of under sea volcanoes and islands
Hot Spot VolcanismThe Cortes Bank Seamount, 100 miles offshore of San Diego, is a 17-mile long remnant of a undersea volcanic mountain range that rises to within 3 feet of the surface
Hot Spot VolcanismFisherman and scuba divers knew about it, but it was not on any nautical maps
The U.S. Navy found it the hard way in 1985 with the aircraft carrier Enterprise
Hot Spot Volcanism“To get the biggest waves at Cortes Bank, you need light winds, low tides, and big storm swells from the northwest all at the same time, a Pacific surfer's version of the ‘perfect storm’.”
The Hawaiian Islands are the classic example of hot spot volcanism
Hot Spot Volcanism
Hot Spot VolcanismEvery island in the Hawaiian Island chain was created by volcanic eruptions that occurred as the Pacific Oceanic Plate crossed over a hot spot
Hot Spot VolcanismIn fact, the 7 main Hawaiian Islands are just the southern most portion of two great undersea mountain ranges, composed of hundreds of volcanoes, that runs for 6000 kilometers (4000 miles) across the floor of the Pacific Ocean
Hot Spot Volcanism
The plate has moved to the northwest for more than 65 million years
The big island of Hawaii is now over the hot spot
The volcanoes that formed the Hawaiian islands are classified as shield volcanoes
Hot Spot Volcanism
Hot Spot VolcanismShield volcanoes are characterized by broad, gentle slopes built up from repeated basaltic lava flows
Hot Spot VolcanismNot all eruption create big islands
Molokini represents one eruption that is slowly being reclaimed by the sea
Hot Spot VolcanismLoihi Volcano, the youngest volcano of the Hawaiian Island Chain, lies about 20 km off the south coast of the Big Island
Currently it rises 3500 meters above the surrounding sea floor and its summit is about 1000 meters beneath the surface