Sansad TV: The Science of Earthquakes | Current Affairs & Hindu Analysis: Daily, Weekly & Monthly - UPSC PDF Download

Earthquakes

What Causes Earthquakes?

• The Earth's outer layer is divided into big and small plates. These plates can move towards, away from, or past each other. Earthquakes occur when stress is suddenly released along faults in the Earth's outer layer.
• As these plates keep moving, stress builds up in the rocks on both sides of a fault. When the stress becomes too much, it's released in a sudden, jerky movement. These earthquakes caused by the plates moving are called tectonic quakes.
• Human activities like building tunnels, creating reservoirs, and geothermal or fracking projects can also cause induced earthquakes. If there's a large reservoir, the earthquakes there are known as reservoir-induced earthquakes.
• When volcanoes are active, the earthquakes associated with them are called volcanic quakes. These are usually not as strong as tectonic quakes and often happen near the surface. They're mostly felt close to where they start.
• Sometimes, the ground shakes due to events like cave-ins, often in areas with lots of caves or near mines. This type of quake is known as a collapse quake.
• Explosions from chemicals or nuclear devices can also make the ground shake. These are called explosion earthquakes.

Why Do Some Places Get More Earthquakes?

• Most earthquakes, over 90%, occur near plate boundaries. These are places where the big pieces of Earth's outer layer move towards, away from, or past each other. The movement of these plates is focused at these boundaries, so big earthquakes are less likely to happen far from them.
• While earthquakes can hit anywhere, they usually follow patterns. Three main zones have a lot of earthquakes each year:
• The Circum-Pacific seismic belt, also known as the "Ring of Fire," around the Pacific Ocean. Around 81% of the world's biggest earthquakes happen here.
• The Alpine earthquake belt, which goes from Java to the Atlantic through the Himalayas and the Mediterranean. About 17% of the biggest earthquakes occur here.
• The submerged mid-Atlantic Ridge, where two plates are moving apart.

In Conclusion

• Unlike other disasters, earthquakes can cause a lot of damage. They often ruin transportation and communication systems, making it hard to help victims quickly.
• Stopping earthquakes isn't possible, so the next best thing is to be ready for them. Instead of just trying to fix things after they happen, it's better to focus on getting ready for them and reducing their impact.