Tibet Earthquake: Causes, Types, Zones and Effects Explained
Why in the news
A strong 7.1 earthquake hit remote Tibet, 75 km from the Everest region, killing at least 126 people.
Key facts
- Earthquake: energy released and spread outward as seismic waves.
- Epicentre: the surface point where shaking is felt most.
- Fault zone: a sharp break in crustal rock along which blocks move apart and slide past each other.
| Type | Cause |
|---|---|
| Tectonic | Constant plate motion strains the crust; the most common kind |
| Volcanic | Stress changes as magma is injected or withdrawn |
| Human-induced | Heavy mining, chemical or nuclear explosions, large reservoirs |
Distribution and measurement
- Quakes can strike anywhere but follow repeating patterns; three big zones: circum-Pacific belt, Alpide belt and mid-Atlantic Ridge.
- India has four seismic zones (II to V), based on seismicity, past quakes and tectonics.
- Seismometers record seismic waves as zig-zags; events are rated by magnitude or intensity.
- Seismic waves are grouped into body waves and surface waves.
Effects
- Ground shaking, settlement, landslides, fires, avalanches, ground displacement, floods from dam failure, structural collapse and tsunamis.
Exam angle
- Indian zones: II to V; large belts: circum-Pacific, Alpide, mid-Atlantic Ridge.
- Most common type: tectonic.