Natural Disasters- Earthquakes

Front 1

energy released from an earthquake

Back 1

form of seismic waves

Front 2

how are earthquakes mapped

Back 2

according to the epicentre

Front 3

where is the focus located

Back 3

directly below the epicentre

Front 4

how are earthquakes measured

Back 4

quantitatively, by the moment magnitude scale

Front 5

What is the moment magnitude scale determined by?

Back 5

1) area ruptured around the fault

2) elasticity of the crust by the fault

3) movement around the fault

Front 6

What is the qualitative scale for earthquakes and how many categories?

Back 6

Modified Mercalli Intensity Scale, based off of 12 categories

Front 7

what is evaluated when identifying the risks of earthquakes?

Back 7

faults

Front 8

blind fault

Back 8

below the surface

Front 9

what are the two types of fault types?

Back 9

strike-slip --> horizontal displacement

dip-slip --> vertical displacement

Front 10

What type of fault is the San Andreas

Back 10

strike slip

Front 11

three types of dip slip faults

Back 11

reverse, trust, and normal

Front 12

What are the time periods of the different fault activity categories?

Back 12

active, movement in past 11600 years

potentially active, movement in past 2.6

inactive, no movement for past 2.6

Front 13

tectonic creep

Back 13

slow movement of rock or sediment along a fracture caused by stress

Front 14

body waves

Back 14

include S and P waves

Front 15

P waves

Back 15

primary waves, fastest and reach the surface first, through the body of earth. Move with push pull and travel thru solids or liquids. *important because that means it travels through the mantle

Front 16

S waves

Back 16

secondary or shear waves, only go through solids and move up and down

Front 17

factors that determine the shaking people experience during an earthquake

Back 17

- magnitude

- distance to epicentre

- focal depth

- direction of rupture

- local soil and rock type

- local engineering and construction

**my excellent father said don't escape

Front 18

What determines the distance to the epicentre?

Back 18

the difference between the arrival of S & P waves

Front 19

How many stations do you need to calculate the distance to the epicentre?

Back 19

3

Front 20

triangulation

Back 20

where the circles intersect on a seismograph

Front 21

attentuation

Back 21

energy being dispersed

Front 22

directivity

Back 22

earthquake energy is focused in the direction of rupture, contributes to increased shaking

Front 23

Are earthquakes felt over larger areas in western or eastern NA? why

Back 23

Eastern, Western NA slows down the waves quicker because it slows in areas with homogeneous, folded, faulted crust

Front 24

alluvial

Back 24

soil deposited by water

Front 25

amplification

Back 25

increase in ground motion during an earthquake

Front 26

earthquake cycle

Back 26

hypothesis that explains successive earthquakes on a fault

Front 27

basis of earthquake cycle

Back 27

strain drops abruptly after an earthquake and then slowly accumulates until the next earthquake

Front 28

Earthquake cycle

Back 28

1. fine

2. stress and strain can be felt

3. rupture occurs, strain is released

4. return to normal, stress starts building again

Front 29

Earthquake stages

Back 29

inactive period

period of minor strain and small earthquakes

period of foreshock

main shock

after shock

Front 30

foreshock

Back 30

small to moderate earthquake that occurs before and in the same general area as the main earthquake

- doesn't always occur

Front 31

mainshock

Back 31

the largest earthquake in a series of associated earthquakes

Front 32

aftershock

Back 32

earthquake occurs shortly after a larger earthquake in the same area

- always occurs

Front 33

deep faults

Back 33

not associated with plate boundaries

Front 34

plate boundary earthquakes

Back 34

occur on faults separating the lithospheric plates

Front 35

types of plate boundary earthquakes

Back 35

strike slip, thrust and normal

Front 36

strike slip earthquakes

Back 36

along transform faults, common along San Andreas

Front 37

thrust

Back 37

aka subduction earthquakes, strongest on earth and can produce tsunamis

- occur on faults that separate converging plates

Front 38

normal fault earthquakes

Back 38

divergent plate boundaries, common along mid-atlantic ridge

Front 39

recurrence interval

Back 39

time between successive events

Front 40

reason for intraplate earthquakes being felt over large areas

Back 40

dense bedrock

Front 41

primary effects

Back 41

ground shaking, surface rupture

Front 42

secondary effects

Back 42

liquefaction, land-level change, fire, tsunami

Front 43

fault scarp

Back 43

linear escarpment at the surface, formed by movement along a

Front 44

liquefaction

Back 44

transformation of water-saturated sediment from solid to liquid. May occur during strong earthquakes when water pressure becomes high enough to suspend particles of sediment within the soil. Once the pressure decreases, the sediment compacts and regains its strength. Watery sand and wilt may flow upward along fractures in the overlying soil material. This can cause extensive damage.

Front 45

fires

Back 45

sever power lines & gas lines, starting fires

Front 46

landslide

Back 46

ground motion produced by an earthquake can cause rock and sediment to move downslope

Front 47

Earthquake natural service functions

Back 47

- channel groundwater to springs

- new mineral resources can be found

- scenic landscapes over millions of years

Front 48

human influence

Back 48

- weight of water reservoirs- dams

- testing nuclear weapons -> strain

- injecting liquid waste

Front 49

Goals of hazard reduction program

Back 49

1. improve national seismograph networks

2. develop awareness of earthquake sources

3. determine earthquake potential

4. predict effects of earthquake on building

5. communicate research to educate the public

Front 50

Example of planning for the earthquake

Back 50

Denali earthquake in Alaska --> pipeline could move

Front 51

precursors to earthquakes

Back 51

1. pattern and frequency of earthquakes- based on foreshock and microearthquakes

Front 52

land-level change

Back 52

1. uplift or subsidence may preceded earthquakes

2. GPS stations can recognize small changes in elevation

3. Seismic gaps along faults

4. physical and chemical changes- groundwater levels and chemistry may occur if rocks expand prior to earthquake