• UGI USER
  • Aug 07, 2024
  • 4 Likes
  • 0 Comments

“ANCIENT EARTHQUAKE SHIFTED GANGA RIVER COURSE”

Why in the news?

  • A study revealed that an earthquake around 2,500 years ago caused the Ganga River to change course.
  • Evidence includes sand dikes and optically stimulated luminescence dating of ancient sediment.
source:lotusrise

Study Discovery:

  • Researchers found evidence of an ancient earthquake shifting the Ganga River’s course around 2,500 years ago.
  • They identified two large sand dikes in the Ganges delta, showing the effects of seismic activity.
  • The earthquake, estimated at magnitude 7 to 8, caused the river to abruptly change its path.

Methodology:

  • Optically Stimulated Luminescence (OSL) Dating: Used to estimate burial time of mineral grains by measuring stored natural radiation.
  • OSL dating of sand dikes and paleochannel samples indicated that the river avulsion and earthquake occurred simultaneously.
About Earthquake:

  • Definition: Natural event caused by the release of energy that generates waves travelling in all directions.
  • Fault: A sharp break in the Earth’s crust where rocks move in opposite directions.
  • Energy Release: Occurs when friction between rock strata is overcome, causing deformation and abrupt sliding of blocks.

Key Terms:

  • Focus/Hypocentre: The point inside the Earth where the earthquake originates.
  • Epicentre: The point on the Earth’s surface directly above the focus; it is the first to experience the earthquake waves.

What are Seismites?

  • Definition: Seismites are deformations in existing sediments caused by seismic activity.
  • Origin: Concept introduced to explain earthquake-induced soft-sediment deformation structures (SSDS).
  • Characteristics: Includes features like liquefaction, sedimentary structures altered by earthquakes.