Earthquake Hits Jhajjar

• 12 Jul 2025

Why in News?

A magnitude 4.4 earthquake with its epicenter near Jhajjar in Haryana struck on 10th July 2025, triggering strong tremors across Delhi-NCR, including Noida, Gurugram, Faridabad, and nearby areas. 

Key Points 

• About the Earthquake: An earthquake is the sudden shaking of the Earth's surface caused by the release of energy in the crust, which spreads outward as seismic waves. 
• Cause of Earthquakes: Earthquakes occur when stress along faults in the Earth's crust overcomes friction, causing rocks to suddenly slip and release energy as seismic waves.  
  • The focus is the point where the energy is released underground, and the epicenter is the surface point directly above it, where shaking is strongest. 
• Types of Earthquake Waves: Earthquake waves are of two types: body waves and surface waves. 
  • Body waves travel through the Earth’s interior and include: 
    • P-waves: Fastest, travel through solids, liquids, and gases, with back-and-forth motion. 
  • S-waves: Slower, move only through solids, with up-and-down motion. 
  • Surface waves travel along the Earth’s surface and are the most destructive, causing major damage. 
• Seismic Shadow Zones: Shadow zones are areas on Earth’s surface where seismic waves are not detected. 
  • P-wave shadow zone: Between 105° and 145° from the epicentre. 
  • S-wave shadow zone: Beyond 105°, as S-waves cannot travel through liquids. 
  • These zones reveal the Earth’s layered structure, including its liquid outer core. 

 

• Types of Earthquakes: 
  • Tectonic: Most common; caused by plate movement along faults. 
  • Volcanic: Linked to volcanic activity in active regions. 
  • Collapse: Caused by cave or mine roof collapses. 
  • Explosion: Result of nuclear or chemical blasts. 
  • Reservoir-induced: Occur near large dams due to water pressure. 
• Measuring Earthquakes: 
  • Richter Scale: Measures magnitude (energy released), ranges from 0 to 10. 
  • Mercalli Scale: Measures intensity (visible damage), ranges from I to XII.