Everything about The Iceland Hotspot totally explained
The
Iceland hotspot is a
hotspot which is partly responsible for the high volcanic activity which has formed the island of
Iceland.
Description
Iceland is one of the most active
volcanic regions in the world, with eruptions occurring on average roughly every five years. About a third of the
basaltic
lavas erupted in recorded history have been produced by Icelandic eruptions. Notable eruptions have included that of
Eldgjá in
984 (the world's largest basaltic eruption ever witnessed),
Laki in
1783 (the world's second largest), and several eruptions beneath
ice caps, which have generated devastating
glacial bursts, most recently in
1996.
Iceland's location astride the
Mid-Atlantic Ridge, where the
Eurasian and
North American Plates are moving apart, is partly responsible for this intense volcanic activity, but an additional cause is necessary to explain why Iceland is a substantial island while the rest of the ridge mostly consists of
seamounts, with peaks below
sea level.
As well as being a region of higher temperature than the surrounding
mantle, it's also believed to have a higher concentration of
water. The presence of water in
magma reduces the melting temperature, and this may also play a role in enhancing Icelandic volcanism.
Theories of causation
There is an ongoing discussion whether the hotspot is caused by a deep
mantle plume or originates at a much shallower depth.
Some
geologists have questioned whether the Iceland hotspot has the same origin as other hotspots such as the
Hawaii hotspot. While the Hawaiian island chain and the
Emperor Seamounts show a clear time-progressive volcanic track caused by the movement of the
Pacific Plate over the Hawaiian hotspot, no such track can be seen at Iceland.
Mantle plume theory
It is believed that a
mantle plume underlies Iceland, of which the hotspot is thought to be the surface expression. This enhances the volcanism already caused by plate separation, both at the centre of the island and at the
Reykjanes ridge to the southwest of Iceland's main volcanic zone. The plume is believed to be quite narrow, perhaps 100 km across, and extends down to at least 400–650 km beneath the Earth's surface, and possibly down to the core-mantle boundary.
Studies suggest that the hotspot is only 50-100
K hotter than its surroundings, which may not be a great enough difference to drive a
buoyant plume.
It is suggested that the lack of a time-progressive track is because the plume may have been located beneath the thick Greenland
craton for a significant time.
Further Information
Get more info on 'Iceland Hotspot'.
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