Volcanic Hot Spots
Volcanic hot spots are a source of high heat energy that supports volcanic activity.
Lava flows that have hardened have helped build up the islands of Hawaii over time.
A volcanic hot spot is an area in the upper mantle from which heat is rising. This heat may come from a mantle plume. In any event, it combines with the lower pressure at the base of the mantle. This causes the rock to crack and melt. The melted rock becomes magma. The magma rises through the cracks and forms volcanoes. This sometimes happens in the middle of a tectonic plate.
The Life of a Volcano
It is important to mention that volcanoes on hotspots are different than volcanoes that form where the continents meet. The volcanoes on hotspots build up and erupts a few times. How does the volcano die? Continental drift!
You see, the hotspot volcanoes sit on top of the tectonic plate. Meanwhile, the hot spot is under the lithosphere. When the plate moves away from the hotspot, the volcano dies. The hot spot will create another volcano in its place. The result is that a trail of volcanoes is left behind. The older volcanoes moving away from the hot spot, and newer ones forming over on top of the hot spot.
Dawn over a volcano at the Hawaii National Park.
Famous Hot Spots
One of the most famous hot spots on Earth is the Hawaiian Islands. The oldest islands found in the Hawaiian island chain consist of dead volcanoes. These volcanoes were active millions of years ago. What happened? The moving crust of the ocean floor has carried them away from the hot spot that feeds the volcanoes. This movement is known as seafloor spreading.
The newest island is the Big Island, which today has two active volcanoes. These volcanoes are fed by the same hot spot that used to feed the dead volcanoes on older islands. Millions of years from now, it is likely that additional islands will form over the same hot spot. This will occur as the Earth’s tectonic plate carries the Big Island away from the hot spot it now sits on.