Earth and Space Unit Test

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The Pacific Ring of Fire

Pacific Ring Of Fire

The Pacific Ring of Fire is an area in the  Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km horseshoe shape, it is associated with a continuous series of oceanic trenches, volcanic arcs, and volcanic belts or plate movements. It has 452 volcanoes and is home to over 75% of the world's active and dormant volcanoes.  The Ring of Fire is sometimes called the circum-Pacific belt. About 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. The next most seismically active region is the Alpide belt, which extends from Java to the northern Atlantic Ocean via the Himalayas and southern Europe. All but 3 of the world's 25 largest volcanic eruptions of the last 11,700 years occurred at volcanoes in the Ring of Fire. The countries that belongs to the Ring of Fire are Chile, Mexico, United States, Antarctica, Russia, Japan, Philippines, Japan, New Zealand, Papa New Guinea, Indonesia, Canada, Peru, Taiwan, and Guatemala. The Ring of Fire is the result of plate tectonics. Tectonic plates are huge slabs of the Earth’s crust, which fit together like pieces of a puzzle. The plates are not fixed but are constantly moving atop a layer of solid and molten rock called the mantle. Sometimes these plates collide, move apart, or slide next to each other. Most tectonic activity in the Ring of Fire occurs in these geologically active zones.

A convergent plate boundary is formed by tectonic plates crashing into each other. Convergent boundaries are often subduction zones, where the heavier plate slips under the lighter plate, creating a deep trench. This subduction changes the dense mantle material into buoyant magma, which rises through the crust to the Earth’s surface. Over millions of years, the rising magma creates a series of active volcanoes known as a volcanic arc. A divergent boundary is formed by tectonic plates pulling apart from each other. Divergent boundaries are the site of seafloor spreading and rift valleys. Seafloor spreading is the process of magma welling up in the rift as the old crust pulls itself in opposite directions. Cold seawater cools the magma, creating new crust. The upward movement and eventual cooling of this magma has created high ridges on the ocean floor over millions of year.

            Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger. Scientists have categorized volcanoes into three main categories: active, dormant, and extinct. An active volcano which has recently erupted and there is a possibility that it may erupt soon. A dormant volcano which has not erupted in a long time but there is a possibility it can erupt in the future. An extinct volcano which has erupted thousands of years ago and there’s no possibility of eruption.

Pacific Ring of Fire