mass movement (15)

Question 1

Mass Movement

Answer 1

The downslope movement of rock, regolith, and soil under the direct influence of gravity

Question 2

What sort of landscapes are rapid mass movements most likely to occur?

Answer 2

Rugged landscapes

Question 3

How does mass movement combine with stream erosion to expand valleys?

Answer 3

Streams cut down while mass movement widens

Question 4

Trigger

Answer 4

A factor or event, such as soil saturation, oversteepened slopes, removal of vegetation or ground shaking, that initiates downslope movement of rock material

Question 5

Angle of Repose

Answer 5

The steepest angle at which loose material remains stationary without sliding downslope

Question 6

Liquefaction

Answer 6

The transformation of a stable soil into a fluid that is often unable to support buildings or other structures

Question 7

Fall

Answer 7

A type of movement that is common to mass-wasting processes that refers to the free falling of detached individual pieces of any size

Question 8

Talus Slope

Answer 8

The characteristic “apron” of angular rock debris that accumulates below mountain cliffs

Question 9

Slides

Answer 9

A movement common to mass-wasting processes in which the material moving downslope remains fairly coherent and moves along a well-defined surface

Question 10

Flow

Answer 10

A type of movement common to mass-wasting processes in which water-saturated material moves downslope as a viscous fluid

Question 11

Rock Avalanche

Answer 11

Very rapid downslope movement of rock and debris. Theses rapid movements may be aided by a layer of air trapped beneath the debris, and they have been known to reach speeds of over 200 km/hr

Question 12

How can material move during a mass movement?

Answer 12

Fall
Flow
Slide

Question 13

Slump

Answer 13

The downward slipping of a mass of rock or unconsolidated material moving as a unit along a curved surface

Question 14

Rockslide

Answer 14

The rapid slide of a mass of rock downslope, along planes of weakness

Question 15

Debris Slide

Answer 15

A type of rockslide consisting of largely unconsolidated rock debris

Question 16

Debris Avalanche

Answer 16

One of the fastest and most destructive types of rockslides consisting of unconsolidated rock fragments

Question 17

Debris Flow/Mudflow

Answer 17

A flow of soil and regolith that contains large amounts of water. Most common in semiarid mountainous regions and on the slopes of some volcanoes

Question 18

Lahar

Answer 18

A debris flow on the slopes of a volcano that results when unstable layers of ash and debris become saturated and flow downslope, usually following stream channels

Question 19

Earthflow

Answer 19

The downslope movement of water-saturated clay-rich sediment (humid regions)

Question 20

Creep

Answer 20

The slow downhill movement of soil and regolith

Question 21

Solifluction

Answer 21

The slow, downslope flow of water-saturated materials common to permafrost areas

Question 22

Permafrost

Answer 22

Any permanently frozen subsoil. Usually found in the subarctic and arctic regions

Question 23

During what season does solifluction in the Arctic occur?

Answer 23

Summer

Question 24

How might disturbing permafrost lead to unstable ground?

Answer 24

Permafrost when melted is turned into water which is less volume than ice, it sinks

Question 25

2 indicators that a slope might be failing:

Answer 25

Cracks
Tilted Trees
Deformation of buildings

Question 26

What are some monitoring methods used for landslides?

Answer 26

Measure size of cracks
Measure changes in soil moisture
Detect noises
Satellites measure position

Question 27

What are two techniques to strengthen failing slopes?

Answer 27

Drainage channels

Bind sliding surfaces or support them