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The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda-Azores High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Horse latitudes. It forms one pole of the North Atlantic oscillation, the other being the Icelandic Low.
The latitudinal movement of the subtropical ridge is strongly correlated with the progression of the monsoon trough or Intertropical Convergence Zone. Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies. [10]
Areas of excess magmatism on the Mid Atlantic Ridge have been called hotspots e.g. the Azores. Gravity field modelling studies have shown that the crustal thickness in this area is 60% greater than normal and the spreading ridge is elevated. [5] The hotspot is asymmetrical (north and south).
The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North American from the Eurasian plate and the African plate , north and south of the Azores triple junction .
A relief map of the Azores Triple Fault region and southern bathymetric zone. The hydrothermal vents and seamounts of the Azores (Portuguese: fontes hidrotermais e montes submarinos dos Açores) are a series of Atlantic seamounts and hydrothermal vents that are part of the Mid-Atlantic Ridge system, giving rise to the archipelago and bathymetric region of the Azores.
In contrast, if formed by past above-water volcanism, they are known as a seamount chain. The largest and best known undersea mountain range is a mid-ocean ridge, the Mid-Atlantic Ridge . [ 1 ] It has been observed that, "similar to those on land, the undersea mountain ranges are the loci of frequent volcanic and earthquake activity".
The Walvis Ridge should then have developed as a result of these periodic stress releases along the Mid-Atlantic Ridge. [ 4 ] O'Connor et al. 2012 found that the hotspot trails in the eastern South Atlantic (Tristan, Gough, Discovery, Shona , and possibly Bouvet ) started forming synchronously 44 to 41 Ma .
Iceland is a 1 km high, 450x300 km basaltic shield on the mid-ocean ridge in the northeast Atlantic Ocean. It comprises over 100 active or extinct volcanoes and has been extensively studied by Earth scientists for several decades. Iceland must be understood in the context of the broader structure and tectonic history of the northeast Atlantic.