Earthquake – Body Waves, Causes & Types – Geography Notes PDF in English & Hindi for UPSC and Other Competitive Exams

Earthquake – Body Waves, Causes & Types: Earthquakes are seismic events caused by the sudden release of energy in the Earth’s crust, resulting in the propagation of waves known as seismic waves. These waves can be classified into two main types: body waves and surface waves. Earthquakes occur due to various geological processes and tectonic activities along fault lines or plate boundaries.

Earthquake – Body Waves, Causes & Types

Here’s an overview of body waves, their causes, and types:

Body Waves: Body waves are seismic waves that travel through the Earth’s interior, propagating in all directions from the earthquake’s focus (the point where the earthquake originates within the Earth). There are two primary types of body waves: P-waves (Primary waves) and S-waves (Secondary waves).

  1. P-waves (Primary waves):
    • P-waves are the fastest seismic waves and are the first to be recorded by seismographs after an earthquake.
    • They are compression waves that travel through solid, liquid, and gas. These waves cause particles to move in the same direction as the wave propagation, alternating between compression and expansion.
    • P-waves can travel through the Earth’s interior, including the mantle and core.
  2. S-waves (Secondary waves):
    • S-waves are slower than P-waves and arrive at seismographs after P-waves.
    • They are shear waves that propagate by causing particles to move perpendicular to the direction of wave travel.
    • S-waves cannot travel through liquids or gases, and they are only able to travel through solids. As a result, the presence of S-waves indicates that the Earth’s outer core is liquid, as they do not pass through it.

Causes of Earthquakes: Earthquakes occur due to the movement or rupture of rocks along faults, sudden volcanic activity, or other tectonic processes involving the Earth’s lithosphere and its interaction with the underlying mantle. The most common causes of earthquakes include:

  • Movement along tectonic plate boundaries (e.g., convergent, divergent, or transform boundaries).
  • Volcanic activity, such as the movement of magma beneath the Earth’s surface.
  • Human-induced seismicity, such as activities related to mining, reservoir-induced seismicity (due to the filling of large reservoirs), or hydraulic fracturing (fracking).

Types of Earthquakes: Earthquakes are classified into various types based on their underlying causes and characteristics. Some common types include:

  • Tectonic Earthquakes: Caused by the movement of tectonic plates along fault lines, such as thrust, normal, or strike-slip faults.
  • Volcanic Earthquakes: Associated with volcanic activity and the movement of magma beneath the Earth’s surface.
  • Induced Earthquakes: Triggered by human activities, such as mining, reservoir-induced seismicity, or hydraulic fracturing.

Understanding seismic waves and the causes of earthquakes is crucial for monitoring seismic activity, assessing earthquake hazards, and implementing measures to mitigate potential risks associated with these natural events. Earthquake-resistant construction and early warning systems are among the strategies used to minimize the impact of earthquakes on communities and infrastructure.

Download Earthquake Notes PDF in Hindi

Download Earthquake Notes PDF in English

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By Team Learning Mantras