Ring of Fire world's 25 largest volcanic eruptions of the last 11,700 years occurred at volcanoes in the Ring of Fire. The famous and very active San Andreas Fault zone of California is a transform fault which offsets a portion of the East Pacific Rise under the southwestern United States and Mexico; the motion of the fault generates numerous small earthquakes, at multiple times a day, most of which are too small to be felt. The active Queen Charlotte Fault on the west coast of the Haida Gwaii, British Columbia, has generated three large earthquakes during the 20th century: a magnitude 7 event
Ring of Gullion similar structures had been described from Scotland. It was emplaced during the Paleogene opening of the Atlantic Ocean during the formation of the North Atlantic Igneous Province. The structure of the ring dyke was produced when the active volcano's caldera underwent collapse producing a concentric suite of faults providing space into which magma was able to intrude. The ring dyke is composite with both porphyritic granophyre and porphyritic felsite components. The composition of the remainder of the volcano today is dominated by gabbro and granophyre and is also the site of a noted occurrence of platinum group elements. The rocks