accretion at spreading ridges. Thanks to bottom imagery obtained from side-scan
sonar coupled with deep towed bottom camera observations, we can also obtain an
indication of ‘‘young’’ sea floor.
Even if we do not have a clear, general pattern for the distribution of volcanic
edifices on the sea floor, nevertheless certain structural features such as the
alignment of volcanoes and lithospheric swells can be used to define and predict
the occurrence of newly created intraplate volcanoes having a ‘‘hotspot origin’’.
Volcanic chains running perpendicularly or obliquely to oceanic ridge segments
(such as the Foundation volcanic chain and the Easter Island volcanic line in
the South Eastern Pacific) as well as undersea aseismic ridges (i.e. Walvis in
the Atlantic, Ninetyeast in the Indian Ocean, and Cocos and Nazca Ridges in the
central Pacific) are areas where upwelling mantle plumes have generated linear
ridges topped by volcanic edifices. These volcanic chains are believed to be the
result of the breaking up of the continental masses, which has thereby enhanced
volcanism.
Thus, an important characteristic of hotspots is that they are usually linear
features and/or they are well-developed isolated volcanic edifices that were built
during magmatic upwelling and often form islands. In fact, most of the world’s
islands are the result of hotspot volcanism. However, hotspot volcanoes such as
Iceland, the Azores, St. Helena, Ascension and Bouvet islands in the Atlantic and
St. Paul, Crozet and Amsterdam islands in the Indian Ocean also occur in association with spreading ridges. Furthermore, hotspot volcanoes could occur as
localized entities, often forming clusters of edifices, such as the Canaries and Cap
Verde Island as well as the tall seamounts in the North Atlantic basin.
Fig. 9.1 World’s map shows the submarine relief and the distribution of hotspots. A Arago smt.,
E Easter Isl., M Macdonald smt., L Louisville smt., F Foundation smt., JF Juan Fernandez Isl.,
G Galapagos, Ma Marquises Isl., T Tuamotu, SG Sal y Gomez Isl., Sm Samoa Isl., S Society Isl.
Satellite altimetry map of Sandwell and Smith (1997) reproduced by D. Aslanian (IFREMER)
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9 Hotspots
sonar coupled with deep towed bottom camera observations, we can also obtain an
indication of ‘‘young’’ sea floor.
Even if we do not have a clear, general pattern for the distribution of volcanic
edifices on the sea floor, nevertheless certain structural features such as the
alignment of volcanoes and lithospheric swells can be used to define and predict
the occurrence of newly created intraplate volcanoes having a ‘‘hotspot origin’’.
Volcanic chains running perpendicularly or obliquely to oceanic ridge segments
(such as the Foundation volcanic chain and the Easter Island volcanic line in
the South Eastern Pacific) as well as undersea aseismic ridges (i.e. Walvis in
the Atlantic, Ninetyeast in the Indian Ocean, and Cocos and Nazca Ridges in the
central Pacific) are areas where upwelling mantle plumes have generated linear
ridges topped by volcanic edifices. These volcanic chains are believed to be the
result of the breaking up of the continental masses, which has thereby enhanced
volcanism.
Thus, an important characteristic of hotspots is that they are usually linear
features and/or they are well-developed isolated volcanic edifices that were built
during magmatic upwelling and often form islands. In fact, most of the world’s
islands are the result of hotspot volcanism. However, hotspot volcanoes such as
Iceland, the Azores, St. Helena, Ascension and Bouvet islands in the Atlantic and
St. Paul, Crozet and Amsterdam islands in the Indian Ocean also occur in association with spreading ridges. Furthermore, hotspot volcanoes could occur as
localized entities, often forming clusters of edifices, such as the Canaries and Cap
Verde Island as well as the tall seamounts in the North Atlantic basin.
Fig. 9.1 World’s map shows the submarine relief and the distribution of hotspots. A Arago smt.,
E Easter Isl., M Macdonald smt., L Louisville smt., F Foundation smt., JF Juan Fernandez Isl.,
G Galapagos, Ma Marquises Isl., T Tuamotu, SG Sal y Gomez Isl., Sm Samoa Isl., S Society Isl.
Satellite altimetry map of Sandwell and Smith (1997) reproduced by D. Aslanian (IFREMER)
302
9 Hotspots