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World Report View

Instability Problem in metaphoric belt of Lesser Himalaya

by Apsara Sapkota | 30-03-2020 13:15 recommendations 0

The sedimentary rocks found in the northern of the main boundary fault and in inner part of the lesser Himalaya are predominantly weak slate to massive and thick beaded dolomite.


Also the imbricate faults, tight folds thrust, cleavage and various systems of joint are encountered in the main boundary fault zone.


a. Folds: A fold is a non-planer configuration of rocks resulting from deformation. When rock layers are subjected to the stress, they fold. Fold forming rocks, being highly stressed, are not considered stable.


b. Faults: Faults are ruptures along with the opposite walls, which have moved passing each other. In rivers fault, footwall (the underlying side of a fault) moves down relation to the hanging wall (the overlying side of a fault). So, shortening of rock-layer occurs. It is extending and shortening stage of rock and forms unstable condition. Hence, faulted areas are hazardous in nature. Also, the faulted terrain is generally very friable and crushed. Hydrothermal fluids may come out through them resulting in weakening of the rocks. Such rocks are more susceptible to attack by rain, river and frost action. So, the faulted terrain is highly unstable.


c. Joints: A surface of fracture without displacement is called joint. A group of more or less parallel joints is known as joint set. When two or more joint sets intersect, they form a joint system. As joint result from tension on rock mass jointed terrain can be considered as an unstable region.


d. Thrust: Low angle reverse faults are called thrusts. Due to thrust, great shortening of the layers takes place. As a result, softer rocks undergo toppling. Due to activeness of the Himalayan frontal thrust and the main boundary thrust in Himalayan range, the entire area is seismically hazardous.



e. Cleavage: Cleavage consists of parallel to sub-parallel fractures often oriented normal to the principal stress. They create less stability since they are small-scale structures.


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15 Comments

  • Sameer Singh says :
    Nice report.
    Keep writing and sharing.
    Posted 31-03-2020 00:43

  • Sushma Sapkota says :
    really informative,
    thank you for sharing
    Posted 30-03-2020 17:06

  • Jasmine Karki says :
    Greetings
    I do hope everything is going well..

    Thank you so much for sharing this report!!
    It was awesome to go through it and learn about lesser himalayas..
    Keep writing and sharing!!

    Green cheers
    Regards
    Jasmine karki
    Posted 30-03-2020 17:04

Sonika Pariyar

  • Sonika Pariyar says :
    Hello Apsara!!
    I enjoyed reading your report!!
    I find it new and different!!
    GREEN CHEERS!!
    Posted 30-03-2020 16:18

  • Kajol Uprety says :
    Nice report Apsara.

    Keep writing.

    Yours,
    Kajol
    Posted 30-03-2020 15:54

  • Ramesh Oli says :
    nice report!
    Posted 30-03-2020 15:34

  • Swesha Dhamala says :
    Thanks for yours nice report!!
    Posted 30-03-2020 13:53

  • Ganga Timilsina says :
    It feels great to know about lesser himalayas, Thanks for your report!
    Posted 30-03-2020 13:43

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