Extension and cracking of the oceanic plate in response to thermal or tectonic stresses provides a pathway for magma, leading to the formation of a linear volcanic chain.
Oceanic Plate Cracking
Image courtesy Bruce Railsback (UGA). Download larger version (jpg, 626 KB).

Figure 3. Extension and cracking of the oceanic plate in response to thermal or tectonic stresses provides a pathway for magma, leading to the formation of a linear volcanic chain.

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