1. 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

2. ?

3. 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

4. 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

5. 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

6. 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

7. Hot Spot Volcanism The 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

8. Hot Spot Volcanism Fisherman 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

9. 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’.”

10. The Hawaiian Islands are the classic example of hot spot volcanism Hot Spot Volcanism

11. Every island in the Hawaiian Island chain was created by volcanic eruptions that occurred as the Pacific Oceanic Plate crossed over a hot spot

12. Hot Spot Volcanism In 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

13. 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

14. The volcanoes that formed the Hawaiian islands are classified as shield volcanoes Hot Spot Volcanism

15. Shield volcanoes are characterized by broad, gentle slopes built up from repeated basaltic lava flows

16. Hot Spot Volcanism Not all eruption create big islands Molokini represents one eruption that is slowly being reclaimed by the sea

17. Hot Spot Volcanism Loihi 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