Earthquake in Uttarkashi

• 24 Jan 2025

Why in News? 

According to the National Center for Seismology (NCS), an earthquake of magnitude 3.5 on the Richter scale hit Uttarkashi in Uttarakhand. 

• The earthquake, which occurred at a depth of 5 km, is part of a sequence of seismic events, with another earthquake of magnitude 4.8 reported earlier in Myanmar.  

Key Points 

• Uttarkashi and Seismic Sensitivity: 
  • Uttarkashi is located in the Himalayan seismic belt, making it highly prone to earthquakes. 
  • The region has previously experienced destructive earthquakes, including the Uttarkashi earthquake (6.8 magnitude) in 1991 and the Chamoli earthquake in 1999. 
• Geological Factors and Vulnerability: 
  • The region is seismically active due to the collision between the Indian Plate and the Eurasian Plate. 
  • Unchecked construction and deforestation have worsened the situation, increasing the risk of destruction in case of major earthquakes. 
  • Uttarkashi and surrounding cities like Dehradun, Nainital, and Mussoorie are densely populated, adding to the vulnerability during seismic events. 

Earthquake 

• About:  
  • An earthquake is the shaking of the Earth's surface caused by the sudden release of energy beneath the Earth’s crust.  
  • This natural event generates seismic waves that travel in all directions through the Earth, resulting in ground movement.  
• Key Terms Related to Earthquake: 
  • Hypocenter: The location beneath the Earth’s surface where the earthquake originates. 
  • Epicenter: The point on the Earth's surface directly above the hypocenter, where the strongest shaking is felt. 
  • Types of Earthquakes: 
    • Fault Zones: Earthquakes that occur due to the movement along fault lines in the Earth’s crust. 
    • Tectonic Earthquakes: Result from the movement of tectonic plates beneath the Earth’s surface. 
    • Volcanic Earthquakes: Caused by volcanic activity, typically due to the movement of magma beneath the Earth’s surface. 
    • Human-Induced Earthquakes: Earthquakes triggered by human activities, such as mining or the injection of fluids into the ground. 
  • Scales of Measuring Earthquakes 
    • Magnitude Scale: 
      • The magnitude of an earthquake refers to the amount of energy released. This is measured using the Richter scale, which ranges from 0 to 10, with each number representing a tenfold increase in amplitude. It provides a measure of the earthquake's strength. 
    • Intensity Scale: 
      • The intensity of an earthquake refers to the level of shaking experienced and the damage caused. The Mercalli intensity scale, developed by Italian seismologist Giuseppe Mercalli, ranges from 1 to 12, with higher numbers indicating more severe shaking and destruction. ]