Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Most volcanoes across the world are caused by the movement of tectonic plates, but despite being a tectonically active region, why are there no volcanoes in the Himalayas? Explain.

Answer 1

Answer:

Introduction:

Volcanoes are the sudden outpour of hot magma or lava along with ash, pyroclastic material, through a rupture in the crust. They are generally formed along with tectonic plate-boundary interaction such as convergent and divergent boundary interaction.

Body:

Tectonic plates:

Tectonic plates are the pieces of lithosphere i.e. earth’s crust and outer Mantle.
There are seven major tectonic plates including the Indian subcontinent, Eurasian plates, etc. and many minor plates.
As per the tectonic plate theory, They are constantly moving and thus interact with each other in the form of plate boundary interactions.

Types of plate-boundary interaction and volcanoes:

Convergent Plate Boundary:
Continental-Oceanic Convergent: When one continental plate and one oceanic plate converge with each other. This led to the formation of subduction zones and thus volcanoes. For example the Pacific Ring of Fire.
Continental-Continental Convergent: When both continental plates converge with each other. This does not lead to the formation of subduction zones. It either faults or folds.
Divergent Plate Boundary:
Oceanic-Oceanic Divergent: When both oceanic plates move away from each other, this leads to the formation of the mid-oceanic ridge (MOR).
Continent-Continent Divergent: When both continental plates move away from each other. This leads to the formation of the rift valleys.
Hotspot volcano: These volcanoes are generally found in Hawaiian islands. They are generally independent of plate boundary interaction.

Reasons for no volcanoes in the Himalayas:

Continent-Continent Convergence:
The Himalayas have also formed at convergent boundaries of the Indian plate and the Eurasian plate i.e. continent-continent convergence.
Unlike continent-ocean convergence where one plate is denser than the other, in continent-continent convergence, at margins, due to lower density, both of the continental crustal plates are too light (buoyant) to be carried downward (subduct) into a trench.

No Subduction Zones:
In most of the cases, none of the two plates subducts or even if one of the plates subducts, the subduction zone will not go deeper than 40 – 50 km. Example: The Indus-Tsangpo suture zone.
Hence, the two plates converge, buckle up (suture zone), fold, and fault.

Lack of lava formation:
Subduction zones are a reason for the melting of the earth’s crust which in turn leads to the creation of lava.
The absence of the Subduction Zone is the reason for the absence of lava.

Conclusion:

Thus the Himalayas lack volcanoes. Further, the earthquakes in the Himalayas are not related to the volcanoes but are related to the suture zones.