A volcanic “hotspot” is an area in the mantle from which heat rises as a thermal plume from deep in the Earth. High heat and lower pressure at the base of the lithosphere (tectonic plate) facilitates melting of the rock. This melt, called magma, rises through cracks and erupts to form volcanoes.

A mantle plume is an upwelling of abnormally hot rock within the Earth’s mantle. As the heads of mantle plumes can partly melt when they reach shallow depths, they are thought to be the cause of volcanic centers known as hotspots and probably also to have caused flood basalts.

Plumes are postulated to rise as the base of the mantle becomes hotter and more buoyant. Plumes are postulated to rise through the mantle and begin to partially melt on reaching shallow depths in the asthenosphere by decompression melting. This melt rises to the surface and erupts to form “hot spots”.

A mantle plume is a large column of hot rock rising through the mantle. The heat from the plume causes rocks in the lower lithosphere to melt. So, as the lithospheric plate above it moves, a string of volcanoes (or other volcanic features) is created.

Because the hot spot is caused by mantle plumes that exist below the tectonic plates, as the plates move, the hot spot does not, and may create a chain of volcanoes on the Earth’s surface.

Mantle plumes can be emitted from the core-mantle boundary region to reach the Earth’s crust. Because of the lateral displacement of the tectonic plates at the surface, the mantle plumes can create a series of aligned hot-spot volcanoes.

Below the Earth’s crust, which is only a few kilometres thick, lies its mantle. “The presumption that the composition of the Earth’s mantle is more or less homogeneous is based on a relatively simple hypothesis,” Murakami explains.

A mantle plume is a narrow cylindrical thermal diapir of low-density material that originates deep in the mantle, either from the mantle–core boundary (at a depth of about 2900km), or from the 670km discontinuity at the base of the upper mantle.

About 95% of the world’s volcanoes are located near the boundaries of tectonic plates. The other 5% are thought to be associated with mantle plumes and hot spots. Mantle plumes are areas where heat and/or rocks in the mantle are rising towards the surface. A hot spot is the surface expression of the mantle plume.

It was suggested that the cause was mantle upwelling. However, normal seismic activity beneath the swell, as well as lack of detected heat flow, caused scientists to suggest dynamic topography as the cause, in which the motion of the hot and buoyant mantle plume supports the high surface topography around the islands.

The mantle is divided into several layers: the upper mantle, the transition zone, the lower mantle, and D” (D double-prime), the strange region where the mantle meets the outer core.

The mantle was originally a cape worn simply to ward off the cold. The mantle was first mentioned in the Old Testament, as a garment worn by several prophets including Elijah and Elisha.

outer core

igneous rocks

The mantle accounts for 60% of the Earth’s mass, making it the thickest layer of the Earth. This pressure can sometimes cause the mantle to leak out onto the surface of the Earth – a volcano!

Exactly what’s in the Earth’s core is open to speculation since we don’t have any samples, but it seems pretty certain that it is primarily nickel and iron with traces of sulfur and other elements. There’s probably not much in the way of radioactive elements, but this is just a guess.

A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. All terrestrial planets (including Earth), a number of asteroids, and some planetary moons have mantles.