Hotspot (geology)

[2] The alternative plate theory is that the mantle source beneath a hotspot is not anomalously hot, rather the crust above is unusually weak or thin, so that lithospheric extension permits the passive rising of melt from shallow depths.

[3][4] The origins of the concept of hotspots lie in the work of J. Tuzo Wilson, who postulated in 1963 that the formation of the Hawaiian Islands resulted from the slow movement of a tectonic plate across a hot region beneath the surface.

The primary hotspots originate from the core/mantle boundary and create large volcanic provinces with linear tracks (Easter Island, Iceland, Hawaii, Afar, Louisville, Reunion, and Tristan confirmed; Galapagos, Kerguelen and Marquersas likely).

The secondary hotspots originate at the upper/lower mantle boundary, and do not form large volcanic provinces, but island chains (Samoa, Tahiti, Cook, Pitcairn, Caroline, MacDonald confirmed, with up to 20 or so more possible).

Other potential hotspots are the result of shallow mantle material surfacing in areas of lithospheric break-up caused by tension and are thus a very different type of volcanism.

An example of this activity is the Ilgachuz Range in British Columbia, which was created by an early complex series of trachyte and rhyolite eruptions, and late extrusion of a sequence of basaltic lava flows.

[13][8] The detailed compositional studies now possible on hotspot basalts have allowed linkage of samples over the wider areas often implicate in the later hypothesis,[14] and it's seismic imaging developments.

[8] In 2020, Wei et al. used seismic tomography to detect the oceanic plateau, formed about 100 million years ago by the hypothesized mantle plume head of the Hawaii-Emperor seamount chain, now subducted to a depth of 800 km under eastern Siberia.

Diagram showing a cross section through Earth at the Hawaii hotspot. Magma originating in the mantle rises into the asthenosphere and lithosphere . A chain of volcanoes is created as the lithosphere moves over the source of magma.
Schematic diagram showing the physical processes inside the Earth that lead to the generation of magma. Partial melting begins above the fusion point.
Map showing approximate location of many current hotspots and the relationship to current tectonic plates and their boundaries and movement vectors
Over millions of years, the Pacific plate has moved over the Hawaii hotspot , creating a trail of underwater mountains that stretches across the Pacific.
Kilauea is the most active shield volcano in the world. The volcano erupted from 1983 to 2018 and is part of the Hawaiian–Emperor seamount chain .
Mauna Loa is a large shield volcano. Its last eruption was in 2022 and it is part of the Hawaiian–Emperor seamount chain .
Bowie Seamount is a dormant submarine volcano and part of the Kodiak-Bowie Seamount chain .
Axial Seamount is the youngest seamount of the Cobb–Eickelberg Seamount chain . Its last eruption was in 2015.
Mauna Kea is the tallest volcano in the Hawaiian–Emperor seamount chain . Many cinder cones have been emplaced around its summit.
Hualalai is a massive shield volcano in the Hawaiian–Emperor seamount chain . Its last eruption was in 1801.
An example of mantle plume locations suggested by one recent group. [ 9 ] Figure from Foulger (2010). [ 4 ]
Distribution of hotspots in the list to the left, with the numbers corresponding to those in the list. The Afar hotspot (29) is misplaced.
Over millions of years, the Pacific Plate has moved over the Bowie hotspot , creating the Kodiak–Bowie Seamount chain in the Gulf of Alaska .
The Hotspot highway in the south Pacific Ocean