UNIVERSITY B.T. & EVENING COLLEGE SEMINAR ON ENVIRONMENTAL SCIENCE TOPIC– MASS MOVEMENT AN IMPORTANT GEOMORPHIC PROCESS SUBMITTED BY-UPASAN ACHARYA ,M.sc.(GEO) ROLL NO-02 B.Ed. SECTION SESSION----- 2011-2012

WHAT IS MASS MOVE MENT? The concept of mass movement or mass wasting was advocated by SHARPE in 1938. The transport also brings substantial changes on the crust of the earth and it therefore has been recognised as an important geomorphic process. Mass movement is the downslope transfer of material through the direct action of gravity .The process can be rapid like landslide ,or slow as creep of soil down the gentle slope of gravity covered field. So, it can be termed as---The movement of weathered material under the influence of gravity and with or without the influence of rainwater is called MASS MOVEMENT.

Factors responsible for mass movement GRAVITY SATURATION OF MATERIAL WITH WATER VIBRATIONS FROM EARTHQUAKES OVERSTEPPING OF SLOPE BY UNDERCUTTING CONSTRUCTION OF CANALS & ROADS STREAM EROSION GLACIAL EROSION WEATHERING PRESSURE RELEASE

TYPES OF MASS MOVEMENT MASS MOVEMENT SUBSIDENCE SLOW FLOWAGE RAPID FLOWAGE LANDSLIDE

SLOW FLOWAGE SOIL CREEP TALUS CREEP ROCK CREEP ROCK-GLACIAL CREEP SOLIFLUCTION

RAPID FLOWAGE EARTH FLOW MOD FLOW DEBRIES AVALANCHE

LANDSLIDES SLUMS DEBRISE SLIDE DEBRIES FALL ROCK SLIDE ROCK FALL

Types of mass movement in a frame

Description of some mass movements SLUMP-A slipping of coherent rock material along the curved surface of a decline. Slumps involve a mass of soil or other material sliding along a curved surface (shaped like a spoon). It forms a small, crescent-shaped cliff, or abrupt scarp at the top end of the slope. There can be more than one scarp down the slope.

Picture of a slump

An Evidence of a slump

Diagram of a slump

LANDSLIDE- The downslope gravitational movement of a body of rock or earthmaterial is termed as landslides .It may be induced by natural agencies (e.g.,heavyrain,earthquake) or it may be caused by human interference with the slope stability.

Images of sikkim landslide after 18th sep,2011 earthquake

An evidence of a landslide

Satellite image shows landslides

CREEP-It is a long term process CREEP-It is a long term process. The combination of small movements of soil or rock in different directions over time are directed by gravity gradually downslope. The steeper the slope, the faster the creep. The creep makes trees and shrubs curve to maintain their perpendicularity, and they can trigger landslides if they lose their root footing. This happens at a rate that is not noticeable to the naked eye.

FLOW-Movement of soil and regolith that more resembles fluid behavior is called a flow. These include avalanches, mudflows, debris flows, earth flow, lahars and sturzstroms. Water, air and ice are often involved in enabling fluidlike motion of the material.

DEBRIES SLIDE- The nearly free fall of earth debries from a vertical cliff is known as debries slide.It is mainly found along the banks of streams.

Diagram of debries slide

Factors responsible for landslide DEFORESTRATION VIBRATIONS FROM EARTHQUAKES CONSTRUCTION OF CANALS & ROADS CONSTRUCTION OF DAMS UNPLANNED URBANIZATION IN HILLS UNPLANNED AGRICULTARAL ACTIVITIES UNPLANNED MINING ACTIVITIES WEAK GEOLOGICAL FORMATION OF SLOPE HEAVY RAINFALL CLOUD BRUST

The trigger effect of landslide

LANDSLIDE-PRONE AREA The most vulnerable regions are mainly in Jammu & Kashmir,Uttarakhand(Kedarnath,B -- adrinath, Gangotri,Y amunetri,uttarkashi etc),sub-Himalayan WestBengal(Darjeeling & Sikkim himalayas),North-East hilly regions.

Map shows landslide prone areas

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