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 arc is convex toward the ocean and concave toward the continent with a deep trench running parallel to the arc along the convex (ocean) side. 1  Arcs and trenches are hundreds of miles long. 2  CROSS-SECTION. 3  Not all volcanic chains are island arcs, however, and not all island arcs are âislandsâ. For example, the Hawaiian Islands are an example of a linear chain of volcanoes in the middle of the Pacific Ocean that is not an island arc. Some âisland arcs have become parts of the continent; the Cascade Range of Washington and Oregon (remember Mt. St. Helens) and the Andes Mountains of South America are examples of âislandâ arcs that are part of continents.