A turbidity current is an underwater current, usually water laden with heavy sediments, that moves rapidly down a slope. Turbidity currents can also occur in other fluids besides water.
Examples of turbidity currents are avalanches consisting of snow and rocks, pyroclastic flows that are volcanic in nature and lava flows, consisting of molten lava and rocks.
This article will give further information about Turbidity Current within the context of the IAS Exam. Also, topics like turbidity currents can be found in the geography segment of the exam.
To know more in detail about the Geography segment, visit the UPSC Syllabus page.
Definition of Turbidity Current
Turbidity currents are those sediments in which sediments are suspended by fluid turbulence. Experts in this field, however, adopted the term to describe a natural phenomenon whose characteristics are mainly of unknown nature.
Turbulence, a rapid motion of sorts, is thought to be the factor that keeps sediment in suspension, but there is a chance that turbulence alone is not the factor responsible for diluting currents.
A turbidity current is also defined as a suspension current in which the interstitial fluid is a liquid (generally water); a pyroclastic current is one in which the interstitial fluid is gas.
Read about Ocean Currents in detail in the linked article.
Factors responsible for Turbidity Current
The following factors are responsible for triggering turbidity currents:
- Hyperpycnal plume: When a suspended sediment is concentrated in large amounts at the mouth of a river, while at the same time the river density is greater than that of sea water, this forms a hyperpycnal plume. The concentration of suspended sediment for river water that enters the ocean is much lower than the sediment concentration needed to create the plume
- Sedimentation in reservoirs: Turbidity currents also cause the transportation and deposition of sediment in narrow mountain reservoirs. The sediments find their way to the deepest area near a dam, where the outflow or inflow of the structure can be affected. Controlling the sedimentation within the reservoir can be achieved through using solids and permeable obstacles with the proper design.
- Underwater Earthquakes: Turbidity currents are caused by tectonic plates shift on the seafloor. The displacement of continental crust through fluidization contributes to the formation of turbidity currents. Earthquakes are supposed to be the cause for deposition in many settings caused by turbidity currents. This is especially true when the local physiography supports preserving the sediments already deposited.
- Canyon-flushing: Large turbidity currents flow into canyons may become self-sustaining and may contain sediment that has previously been introduced into the canyon by littoral drift storms or smaller turbidity currents
- Slumping: Sediments accumulated at the top of a continental sole can create turbidity currents due to its capacity being exceeded beyond a certain limit. This will result in slumping and sliding of sediments at a downward motion.
- Convective sedimentation beneath river plumes: A river layered with sediment will cause a buoyancy that can cause a secondary turbidity current on the ocean floor.
Turbidity Current – UPSC Notes:- Download PDF Here
Find notes on UPSC Geography by visiting the linked article.
Frequently asked Questions Related to Turbidity Currents
Where is a turbidity current most likely to occur?
What rocks form in turbidity current?
What causes turbidity currents?
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