In
geology, the places known as
hotspots or
hot spots are
volcanic regions thought to be fed by underlying
mantle that is anomalously hot compared with the surrounding mantle. They may be on, near to, or far from
tectonic plate boundaries. Currently, there are two hypotheses that attempt to explain their origins. One suggests that they are due to hot
mantle plumes that rise as thermal
diapirs from the core–mantle boundary. An alternative hypothesis postulates that it is not high temperature that causes the
volcanism, but lithospheric extension that permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well known examples include
Hawaii and
Yellowstone.