APPROACH
Introduction: Mention about Pacific ring of fire.
THE BODY
• Discuss the geophysical characteristics of Circum-Pacific Zone.
Conclusion: As it is tectonically most active zone, the frequency of natural hazards like earthquakes, tsunami, volcanic eruptions is also more.
Circum-Pacific Zone is a region surrounding Pacific Ocean. It is also called ‘rim of fire’ or ‘Pacific ring of fire’ due to the existence of active volcanoes in this area.This is the world’s most seismically and volcanically active zone.
Geophysical characteristics:
1. Convergent Plate boundaries and presence of subduction zone: In this zone, Pacific plate (which is an oceanic plate) gets subducted under plates like North American plate, South American Plate, Eurasian Plate to form subduction zone. Therefore, there is presence of many deep trenches in this zone e.g. Mariana trench, Japan trench, Aleutian trench etc. (refer to given map for their location).
2. Presence of volcanoes along the zone: Due to presence of subduction zone of different plates, there is melting of oceanic crust and formation of magma in subduction zone. This magma comes on the earth’s surface in the form of volcanic eruptions. Most of the volcanoes of the world are located along circum-pacific zone. g. Mount St. Helens (North America), Mount Pinatubo (Philippines).
3. Presence of Andes and Rockies mountain ranges: Formation of these mountain ranges due to subduction of oceanic plates under Continental plates. Many active volcanoes are located in these mountain ranges.
4. Formation of island arcs:Due to ocean-ocean convergence of plates along the western Pacific Ocean, there is formation of island arcs and archipelagoes such as Japanese islands arc, Philippine islands and Indonesian archipelagoes.
5. Earthquakes: About 85% of the world’s earthquakes happen in this zone. They are largely deep focus earthquakes due to presence of convergent plate boundaries. Sometimes, this also results into Tsunami. E.g. 2011 tsunami in Japan.
Conclusion
Plate tectonic theory has successfully explained above geophysical characteristics of circum-pacific zone. As it is tectonically most active zone, the frequency of natural hazards like earthquakes, tsunami, volcanic eruptions is also more.
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