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A hotspot's position on the Earth's surface is independent of tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. [2]
Tectonic plates generally focus deformation and volcanism at plate boundaries.However, the Hawaii hotspot is more than 3,200 kilometers (1,988 mi) from the nearest plate boundary; [1] while studying it in 1963, Canadian geophysicist J. Tuzo Wilson proposed the hotspot theory to explain these zones of volcanism so far from regular conditions, [3] a theory that has since come into wide acceptance.
The hotspot's most recent caldera-forming supereruption, known as the Lava Creek Eruption, took place 640,000 years ago and created the Lava Creek Tuff, and the most recent Yellowstone Caldera. The Yellowstone hotspot is one of a few volcanic hotspots underlying the North American tectonic plate; another example is the Anahim hotspot.
This results in hotspot volcanism or intraplate volcanism, in which the plume may cause thinning of the crust and result in a volcanic island chain due to the continuous movement of the tectonic plate, of which the Hawaiian hotspot is an example. Volcanoes are usually not created at transform tectonic boundaries where two tectonic plates slide ...
Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, 3,000 kilometers (1,900 mi) deep within Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another.
The plate theory is a model of volcanism that attributes all volcanic activity on Earth, even that which appears superficially to be anomalous, to the operation of plate tectonics. According to the plate theory, the principal cause of volcanism is extension of the lithosphere.
Another hypothesis for unusual volcanic regions is the plate theory. This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension. [3]
Over short geological timescales the hotspots appear to be fixed relative to one another, forming a reference frame against which plate motions can be measured. As tectonic plates move relative to a hotspot, the location of magmatic activity on the plate shifts, causing the development of time-progressive chains of volcanoes such as the ...