chapter 8: geologic hazards

Question 1

What are the factors affecting slope failures? ____

Answer 1

topography, geology, weather, seismic activity

Question 2

______ in terms of inclination and height of the hill/cliff.

Answer 2

topography

Question 3

_____ in terms of the material structure and strength of rocks and mineral formation.

Answer 3

geology

Question 4

______ in terms of the seepage forces and run-off quantity and velocity of water during rainy days.

Answer 4

weather

Question 5

______ as it affects inertial and seepage forces and due to the crustal movements of the earth

Answer 5

seismic activity

Question 6

What are the seven methods of controlling slides? _____

Answer 6

1. change the slope geometry to decrease the driving forces or increase the resisting forces by removal of very large volume of loose materials or debris along the top and side of slopes
2. control surface water infiltration to reduce seepage forces
3. planting the slope with thick, fast growing native vegetation and should be applied with burlaps bags and sprayed with mulch to increase growth
4. sealing cracks and fissures with asphalt or soil cement and combines with grading to fill the cracks with soil
5. providing retention structures to increase the resisting forces by constructing surface drains or drainage galleries, retaining walls and cribs, tie bars and shotcreting/guniting the rock slopes
6. benching and placing materials at the toe to form a counterbermig forces, increase the driving forces
7. driving sufficiently strong piles at an earth slope to a sufficient depth in a reliable stratum or strong rock founds
   ation

Question 7

These hazards are less disastrous than any other hazards in terms of lives lost but the total property damage exceeds than the others.

Answer 7

ground subsidence, settle/collapse

Question 8

______ is defined as a downward movement of the natural ground surface to which no structures have been built.

Answer 8

subsidence

Question 9

_____ is defined as a downward movement of the ground surface with the structure as caused by its dead life load and other forces.

Answer 9

settlement or collapse

Question 10

What are the four causes of ground subsidence? _____

Answer 10

1. extraction of fluids or solids, solution of rocks or a cementing agent in soils
2. erosion
3. physicochemical changes such change in environment condition as a result of human activities
4. earthquakes or tectonic movements

Question 11

What are the four sources of earthquakes? _____

Answer 11

1. tectonic
2. volcanic
3. minor earth shaking attributed by the collapse of mines or caverns, to large slope failures such as avalanches, or to meteorites striking the earth
4. man-made disturbances like blasting

Question 12

______ are caused by a rupture in or near the earths’s crust that is usually associated with a faults, crustal warping pr fracturing in rocks.

Answer 12

tectonic

Question 13

_____ are caused by effect of volcanic eruptions.

Answer 13

volcanic

Question 14

What are the three causes of settlement? _____

Answer 14

removal of lateral support, sheared failure, fluctuation of the water table

Question 15

_____ if an excavation is made next to a structure, the structure tend to move downward at a point due to the lateral yield of the slope.

Answer 15

removal of lateral support

Question 16

______ causes the tipping of the structure and happens where the structure are constructed in saturated fine sand mass permitting the flow laterally it flows along together with the structure it supports.

Answer 16

sheared failure

Question 17

_____ as the water table drop, either naturally or by pumping, the buoyancy in the dewatered region vanishes and the apparent weight of the earth mass & the structure increases.

Answer 17

fluctuation of the water table

Question 18

____ is the center or source of the shock.

Answer 18

focus

Question 19

____ is the place on the earth’s crust where the earthquake originates.

Answer 19

focus

Question 20

____ the point on line on the surface directly above the focus.

Answer 20

epicenter

Question 21

______ the projection of the focus on the ground surface or a limited area of the ground surface.

Answer 21

epicenter

Question 22

Most earthquakes occur from 5 to 15 miles below the surface. However the foci of some earthquakes have been located at ____ miles down.

Answer 22

42

Question 23

What are the two measurements of an earthquake? _____

Answer 23

intensity, magnitude

Question 24

_____ is a qualitative value based on the response of people and objectives on the earth’s surface.

Answer 24

intensity

Question 25

_____ is a quantitative value computed from the seismograph.

Answer 25

magnitude

Question 26

_____ is the study of earthquakes.

Answer 26

seismology

Question 27

_____ is one who applies the methods or principles pf seismology as in earthquake prediction or seismic exploration.

Answer 27

seismologist

Question 28

_____ is an instrument used to measure seismic waves.

Answer 28

seismograph

Question 29

What are the eight major effects of earthquakes? ____

Answer 29

1. collapse of man-mae structure especially those that can not withstand its magnitude 2. disruption of utilities such as light and water 3. fires caused by short circuits 4. landslides and avalanches 5. ground subsidence and settlement 6. slope failures 7. tsunamis 8. floods

Question 30

What are the four prevention of heave? ____

Answer 30

1. excavation of the upper portion pf the swelling clays, mixing it with lime 2. injection of lime 3. coating with bitumen or a comparable air tight substance 4. preflooding to permit expansion, then designing to contend with settlements of the softened material and attempting to maintain a balance between swell and consolidation

Question 31

What are the five ways of flood control? _____

Answer 31

1. floodplain zoning 2. construction in high elevation 3. diking to contain water 4. channel straightening and lining 5. flood-control dams

Question 32

______ affords the best protection against flooding from the aspect of community development, since construction can be prohibited.

Answer 32

floodplain zoning

Question 33

_____ as a necessary solution for many rapidly growing cities which are greatly affected by natural and development changes.

Answer 33

diking to contain water

Question 34

_____ is a solution often applied to small rivers and streams to increase the flow of velocity and reduce the flood hazard and bank erosion.

Answer 34

channel straightening and lining

Question 35

______ constructed upstream serve as storage reservoirs and are the most effective construction solution to flood protection.

Answer 35

flood-control dams

Question 36

What are the four causes of slope failures/slides? _____

Answer 36

1. the gravity of the weight of the slope materials which have saturated by water 2. the increase in gravity and decrease in shearing strength acting together of the soil and rocks present along the slopes 3. the removal of the lateral support particularly the removal of the toe of the slope 4. ground movements caused by volcanic and tectonic movements like earthquake

Question 37

What are the two slide-producing agents? ____

Answer 37

gravity, surface water

Question 38

What are the classifications of slope failures? ____

Answer 38

creep, flow, falls, slides, avalanche and landslides

Question 39

_____ are characterized by a sudden dislodgment of single or multiple blocks of soil or rock which fall in free descent.

Answer 39

falls

Question 40

It is caused by the undercutting of slopes due to stream or wave erosion, usually assisted by seepage forces.

Answer 40

falls

Question 41

_____ are characterized by a slow to rapid movements of soil and rocks along some well-defined planar failure surface.

Answer 41

slides

Question 42

In ____ it is necessary to consider the character of the rock and its structure. Some rocks are hard and expensive to blast; others are soft or highly fractured that they may not stand up well on steep faces.

Answer 42

road cuts on a hill side

Question 43

The _____ should be carefully considered in order to insure stability and constant slides.

Answer 43

slope of the sides of the road cut

Question 44

_____ can usually be left standing with a steep face.

Answer 44

firm rock

Question 45

_____ must be given their angle of repose.

Answer 45

unconsolidated materials

Question 46

______, occurring during or after heavy rainfall and snow melt, cause ruin off to exceed the carrying capacity of the normal river channel which consequently overflows its banks and floods the adjacent valley.

Answer 46

natural floods

Question 47

_____ of several kinds increase the incidence of flooding.

Answer 47

human activities

Question 48

_____ involving the filling decreases the natural storage capacity, consequently increasing the extent of the floodplain.

Answer 48

construction in the river floofplain

Question 49

______ represent substantial danger to humans and their works which may exist as a consequences of natural events, but often they are the result of human activities.

Answer 49

geologic hazards

Question 50

What are the four types of geologic hazards? ____

Answer 50

floods, slope failures, ground subsidence, earthquakes