Related words. 1  poke noun. 2  poke around phrasal verb. 3  poke fun (at) phrase.  a pig in a poke 1  phrase. poke a hole in something phrase.  poke/shove/stick your nose into something 1  phrase. poke about phrasal verb at poke around.  poke fun at phrase at make fun of.
Because the subduction zone (which is also the plate boundary) is generally an arc-shape, geologists named those volcanoes volcanic arcs. A volcanic arc built on continental crust is called a continental arc; when built on oceanic crust the volcanoes form an island arc. Volcanic arcs are made of an arc-shaped chain of volcanoes. 2  The position of which could be continental or mid-ocean. 3  While an island arc must be offshore and does not necessarily be volcanic (e.g. Hellenic arc).
The collision of the plates causes subduction and destruction of the ocean plate. Note the formation of a trench at the plate boundary and a line of volcanoes called an island arc. (Diagram by Phyllis Newbill). In the diagram above, the ocean lithosphere subducts underneath the continental lithosphere.This results in the destruction of the ocean lithosphere and the formation of magmas (with island arc volcanoes above). The deep ocean trench marks the plate boundary and is where the subduction of the ocean lithosphere begins.t these boundaries, two neighboring plates move away from each other. Continental rift valleys are characterized by normal faulting and basalt-rich volcanoes. The diagram shows a typical continental rift. Note the central rift valley that includes volcanoes.