Question

What is slumping?
A. Rockfalls
B. The weathered materials do not move downward but sink ‘in situ’
C. Earthquake
D. All of the above

Answer 1

Hint: Slumping occurs at intermittent or irregular intervals. This leads to the movement of materials downwards.

Complete Answer:Slumping is a kind of mass wasting or mass movement.

According to geology when weathered material, instead of moving downward, sinks ‘in situ’ it is known as slumping. One of the reasons for the occurrence of slumping is earthquakes and another reason can be if the foot of the slope is made up of unconsolidated material which leads to removal of buttressing earth present at the foot of the slope.

Slumping occurs in the areas where there are alternating layers of permeable and impermeable rocks. One must understand the difference between slumping and sliding. In sliding the materials fall downward in an inclined plane whereas in slumping the materials fall downward along a curved plane.

Some of the major causes of slumping are - earthquakes, weting, freezing and thawing, undercutting, loading of a slope, etc.

The speed of slump varies a lot, it ranges from meters per second to meters per year. If there has been an earthquake or heavy continuous rains then the chances of sudden slump increases.

Slumps can also occur underwater. They can occur along the margins of continents and islands. Slumps can occur underwater because of tidal action or a large seismic event.

So, the correct answer is option D.

Note: One the largest known slumps occurred in Africa. It happened on the south eastern edge of the Agulhas Bank. The Hawaiian Islands have their unusual topography because of many slumps that have taken place for millions of years.