EARTHQUAKE IMPACTS ON GANGA COURSE

EARTHQUAKE IMPACTS ON GANGA COURSE

WHY IN NEWS?

A recent study suggests that an earthquake about 2,500 years ago might have abruptly altered the course of the Ganga River.

ABOUT EARTHQUAKE

• It is a sudden and continuous shaking of the Earth's surface.
• Generation – It is caused by the release of stored energy of earth surface which generates seismic waves, which propagate through the Earth and cause the ground to shake.
• Seismic waves - A seismic wave is a mechanical wave of energy travelling through the Earth or another planetary body.

CAUSES OF EARTHQUAKE

1. Movement of Plate Tectonics
2. Pressure Building up along Faults
3. Volcanic Activity
4. Large Scale Mining

IMPACTS OF THE EARTHQUAKE

1. Generate Tsunamis
2. Trigger Landslides
3. Soil Liquefactions
4. Change River Courses
5. Structural Damages
6. Loss of life

HOW EARTHQUAKE CHANGES RIVER COURSE

• Displaces riverbeds- Earthquake can cause the ground to shift, and can alter the course of rivers by moving their beds or changing their direction.
• Alters water flow patterns- Shifts in the riverbed or new obstacles can change the speed and volume of river flow.
• Blockage by Landslides- Landslides due to earthquake can block rivers and form temporary or permanent dams.
• Alters sediment load- An increase in sediment flow into rivers due to landslides or soil erosion, affects river morphology.
• Creates new channels- All these factors can result in creating new pathways for rivers, leading to the formation of new river channels.

WHAT IS THE OUTCOME?

• It suggests that the impact of large earthquakes can be more destructing than previously thought because avulsions have caused some of the deadliest floods in human history.
• The devastating impacts of earthquakes and flooding can be severe for heavily populated regions like the Ganges-Meghna-Brahmaputra delta.
• Rivers Ganges are more prone to avulsion now owing to factors like
  • Rapid subsidence, i.e. sinking of the ground near the river banks due to “widespread embankment
  • Climate-change–induced rise in sea levels and extreme weather events
• Thus the lessons learned from this ancient earthquake may hold important insights for navigating the Ganga's ever-changing course in the years to come.