Day 83 – Q 1. With the help of suitable examples, examine the correlation between plate tectonics and earthquakes.

1. With the help of suitable examples, examine the correlation between plate tectonics and earthquakes. 

उपयुक्त उदाहरणों की मदद से, प्लेट टेक्टोनिक्स और भूकंप के बीच सहसंबंध की जांच करें।

Introduction:

According to the theory of plate tectonics, Earth is an active planet. Its surface is composed of many individual plates that move and interact, constantly changing and reshaping Earth’s outer layer. Volcanoes and earthquakes both result from the movement of tectonic plates. 

Body

• The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. There are worldwide patterns to major geological events (such as earthquakes) that coincide with plate boundaries. Earthquakes often occur along the boundaries between colliding plates.
• The Earth’s lithosphere is broken into distinct plates which are floating on a ductile layer called the asthenosphere (upper mantle). The tectonic plates) vary from minor plates to major plates, continental plates (Arabian plate) to oceanic plates (Pacific plate), sometimes a combination of both continental and oceanic plates (Indo-Australian plate).
• Three main types of boundaries exist between tectonic plates. The first, called a divergent boundary, occurs most often at mid-oceanic ridges. Here, two plates move away from each other, forming a break, or rift, in Earth’s crust. Magma from the mantle rises to fill the gap, creating new crust. 
• Earthquakes (shallow focus) are common along divergent edges.
• Example: East African Rift Valley, Mid-Atlantic Ridge, minor earthquakes near Azores and Iceland etc
• The second type, called a convergent boundary occurs where two plates moving toward each other meet. If at least one of the plates is made up of relatively dense oceanic crust, the denser of the two plates subducts, or slides beneath the other. If both plates are made up of continental crust, very little subduction occurs. Instead, the plates buckle and fold to create valleys, ridges, and high mountain ranges.
• These boundaries tend to produce most of the earthquakes that have magnitudes greater than 6.0, and subduction zones produce the deepest earthquakes. 
• Examples include deep ocean trenches like the Peru–Chile trench, Himalayan Boundary Fault, Andes etc
• The last type of boundary is called a transform boundary. At these locations, plates slide roughly alongside each other in opposite directions. The plates often get stuck as they move past each other, leading to a build-up of tension, which is ultimately released in the form of an earthquake.
• Transform boundaries typically produce large, shallow-focus earthquakes. Although earthquakes do occur in the central regions of plates, these regions do not usually have large earthquakes. 
• Examples include the San Andreas Fault and the Anatolian fault, earthquakes close to and in California
• The zones along plate boundaries are the most geologically active regions on Earth. Earthquakes are common along all types of boundaries and occur all over the world. One of the most well-known plate boundaries encircles the Pacific Ocean, and the frequent earthquakes and volcanic activity along this circle of boundaries have caused it to be dubbed the Ring of Fire.

TLP Phase 1 – Day 83 Synopsis

Conclusion

Seismologists associate different kinds of seismic activity with what is happening at different types of plate boundaries. The theory of plate tectonics can be used to provide a simplified explanation of the global distribution of earthquakes, their evolution and provide a background research for sustaining loss and resistive measures.