Ground Subsidence and Karst Subsidence

Question 1

Defined as the lowering of the land surface due to
sinkhole development

Answer 1

Karst subsidence

Question 2

t or f: Sudden collapse events are rarely major disasters, certainly not anywhere near the scale of the
earthquake, volcanic, tsunami, or landslide disasters

Answer 2

t

Question 3

t or f: Slow subsidence of areas can cause as much
economic damage, although spread out over a
longer period of time.

Answer 3

t

Question 4

this is one of the most dangerous geohazards according to mgb due to its extreme unpredictibility

Answer 4

subsidence due to sinkhole collapse

Question 5

triggering mechanisms for subsidence

Answer 5

carbonate dissolution
removal of solids and mine related collapse
fluid withdrawal

Question 6

Water in the atmosphere can dissolve small amounts
of _________ which results in rain water having a small amount of _____________ when it falls on the earth’s surface

Answer 6

carbon dioxide (CO2) ; carbonic acid (H2CO3)

Question 7

carbonic acid plus calcium carbonate prduces

Answer 7

calcium ions and bicarbonate ions (dissolved CaCo3)

Question 8

examples of mining activities that results in collapse

Answer 8

salt mining (injection of fluid and extraction of brine)

coal mining (room and pillar mining)

Question 9

If fluids are withdrawn from below the surface, a
_____________ may occur resulting in the
removal of support and possible collapse.

Answer 9

decrease in fluid pressure

Question 10

two of the most important fluids that occur beneath the surface

Answer 10

groundwater and petroleum (oil and natural gas)

Question 11

first recognized subsidence due to oil withdrawal

Answer 11

Wilmington oil field of Long Beach, California (1940)

Question 12

are affected by Wilmington oil field subsidence

Answer 12

50km2

Question 13

vertical displacement if Wilmington oil field subsidence

Answer 13

9m

Question 14

reduced area of subsidence (Wilmington) ; what year

Answer 14

8km2 ; 1962

Question 15

other technical term for sinkhole

Answer 15

doline

Question 16

the word “doline” derives from the _________ word “____” meaning _____________

Answer 16

Slovene ; dolina ; depression in the landscape

Question 17

english terms for sinkholes with rather loose connotations

Answer 17

sinkhole, swallet, and swallow hole

Question 18

several processes that form doline

Answer 18

surface solution
cave collapse
piping
subsidence
stream removal of superficial covers

Question 19

five-fold classification of dolines

Answer 19

1. Solution Dolines
2. Collapse Dolines
3. Suffossion Dolines
4. Subsidence Dolines
5. Alluvial stream-sink dolines

Question 20

Start where solution is concentrated around a favorable point such as joint intersections. The solution lowers the bedrock surface, so eating out
a small depression .The depression traps water, encouraging more solution and depression
enlargement.

Answer 20

Solution Dolines

Question 21

are produced suddenly when the roof of a cave formed by underground solution gives way and fractures or ruptures rock and soil.

Answer 21

Collapse dolines

Question 22

form in an analogous manner to subjacent karst-collapse dolines, with a blanket of superficial deposits or thick soil being washed or falling into widened joints and solution pipes in the limestone beneath.

Answer 22

suffossion dolines

Question 23

form gradually by the sagging or settling of the ground surface without any manifest breakage of soil or rock

Answer 23

subsidence dolines

Question 24

form in alluvium where streams descend into underlying calcareous rocks

Answer 24

Alluvia stream-sink dolines

Question 25

the point at which a stream disappears underground.

Answer 25

stream-sink

Question 26

manifestations of a subsidence doline

Answer 26

tilted vegetations

Question 27

term for coalesced doilines

Answer 27

uvala

Question 28

small lake in closed depression
in limestone, due to an impervious clay floor or to
intersection of depression with the water table.

Answer 28

solution sinkholes

Question 29

lowering of the surface of the
ground because of removal of support. Caused in karst areas by subterranean solution or collapse of caves

Answer 29

subsidence sinkholes

Question 30

a closed depression formed by
the collapse of tie roof of a cave

Answer 30

collapse sinkhole

Question 31

a vertical cylindrical hole - attributable
to solution, often without surface expression, filled with debris, such as sand, clay, rock chips, and bones

Answer 31

pipe sinkhole

Question 32

pipe sinkholes are filled with debris such as

Answer 32

sand, clay, rock chips, and bones

Question 33

causes of sinkhole collapse

Answer 33

• Gravity
• Lowering of water table
• Heavy rainfall (sinkhole flooding)
• Ground movement due to earthquake
• Ponding of subterranean river
• Subsidence in coral reef

Question 34

how are sinkholes formed?

Answer 34

diagram go

Question 35

signs of sinkholes in your backyard

Answer 35

topography
ponding of water
tension cracks
orientation of vegetation

Question 36

Splitting into chips or fragments
where fragments of a material (spall) are
ejected from a body due to impact and stress.

Answer 36

spalling

Question 37

g=fragments of a material ejected from a body du to impact and stress

Answer 37

spall

Question 38

predicting and mitigating subsidence hazards

Answer 38

• Generation of subsidence susceptibility maps
• Borehole studies
• Ground Penetrating Radar Surveys
• Mapping of tension cracks and subsidence features
• Regulate groundwater extraction
• Fluid injection
• Grouting

Question 39

injection of special cement on the subsurface

Answer 39

grouting

Question 40

signs that an area has karst topography

Answer 40

shard ridges, conical hills

Question 41

age of limestones in the philippines

Answer 41

eocene - pleistocene