The Pacific Rim of Fire is a horseshoe shaped region along the shores of the Pacific Ocean named for its numerous active volcanoes. It is the most volcanically active location in the world, and is home to 75% of the world’s active and dormant volcanoes. It is also where 80% of the earth’s earthquakes occur. California, Mexico, Alaska, Canada, Russia, Japan, Ecuador, Peru, Bolivia, Argentina, and Chile are among places within the Pacific Rim of Fire. Of the 25 largest volcanic eruptions to have occurred in the last 11,700 years, 88% of them occurred within the Pacific Rim of Fire. The1980 eruption of Mt. St. Helens, in 1980, within the Pacific Rim of Fire, was the most powerful and deadliest volcanic eruption in American history. The South American nation of Bolivia is home to the world’s greatest number of active volcanoes. In 1991, the eruption of Mt. Pinatubo in the Philippines was so powerful that its effects were felt around the world. It was the second most powerful eruption in modern history.

The volcanoes at the Pacific Rim of Fire are formed where giant oceanic plates meet and collide with continental plates. The movements and collisions of these massive plates is called plate tectonics. When these plates collide, one of them goes underneath the others. Since the Pacific Plate is older, colder, and denser than the surrounding plates, it subducts (goes underneath) the other plates during this process. When this happens, the Pacific Plate brings a lot of water down into the earth with it, making the crust and upper part of the mantle easier to melt. This molten rock (magma) then rises through the earth’s crust and creates volcanoes! This process also creates a lot of earthquakes as the Pacific Plate scrapes against the plates it subducts.