Earthquake in Afghanistan

Context

Due to its low depth and subpar construction, the recent 6.0-magnitude earthquake in Afghanistan caused more than 800 fatalities and 2,000 injuries.

About Earthquake

• The shaking of the ground caused by movement beneath the earth’s surface when two blocks slip past each other along a fault line is known as an earthquake.
• This abrupt movement releases stored elastic strain energy in the form of seismic waves, resulting in ground tremors.
• The hypocenter is the point beneath the surface of the planet where the earthquake originates, while the epicenter is the point right above it on the surface of the world.
• The Richter scale is used to measure the magnitude of an earthquake, while the Mercalli scale, which is based on observable damage, is used to determine its intensity.

Causes of Afghanistan’s Earthquake

• The affected region in Afghanistan is in the seismically active Himalayan and Hindu Kush mountains and their foothills due to the persistent friction, in between the Indian and Eurasian tectonic plates.
• The immense pressure caused by the Indian Plate’s northward movement (about 5 cm annually) has resulted in several fault lines throughout Afghanistan, Pakistan, and northern India.
• The epicenter of the earthquake was just 8 kilometers below the surface, which increased the impact on the ground.

Effects of Earthquakes

• Earthquakes cause significant fatalities as a result of fires brought on by the shaking, landslides, tsunamis, and collapsing structures.
• Common repercussions include psychological trauma, community structure loss, and population displacement.
• The earthquake in Afghanistan had a shallow epicenter, which increased the ground shaking and devastation.
• The usage of mud brick and stone in rural regions without engineering criteria resulted in buildings being prone to collapse due to their fragile construction.

Seismic waves

• An earthquake produces seismic waves, which are energy waves that travel through the layers of the Earth, causing ground shaking.
• They are primarily divided into two categories: surface waves and body waves.
  • • • Body Waves: These waves propagate through the interior of the Earth. In the event of an earthquake, they arrive sooner and at a higher speed than surface waves.
      • Surface waves have a larger amplitude and are thus more destructive, but they move more slowly along the Earth’s surface than body waves.
• Different Kinds of Body Waves
  • P-waves (Primary Waves): These are the quickest seismic waves, and they are the ones that seismographs first capture. Their motion is longitudinal or compressional.
    • • P-waves have the ability to propagate through gases, liquids, and solids.
  • S-Waves (Secondary Waves): They travel in a transverse way, with particles moving perpendicularly to the wave’s direction of propagation.
    • • Because liquids and gases cannot withstand shear stress, S-waves are only able to propagate through solids.

Source: The Hindu

Mains PYQ

Q. Vulnerability is an essential element for defining disaster impacts and its threat to people. How and in what ways can vulnerability to disasters be characterized? Discuss different types of vulnerability with reference to disasters. (2019)

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