Exam 2 Flashcards
Explain the process that heats up the earth’s atmosphere
Solar radiation hits the surface of the earth
Heat get absorbed but infrared bounces out and the green house gas capture that and store the energy
This heats up the atmosphere
The “hokey stick” diagram shows
A dramatic increase in temperature compared to the average
What is the component of volcano eruptions contributing to global warming and global cooling
The co2 and water vapor that builds up and erupts but the sulfuric acid that comes out also reflects solar radiation and helps with cooling
Overall contribute global cooling more
What contributes to natural cycles of global cooling and warming
- Changes in eccentricity
- Changes in the tilt of the earth
- The earths precession (wobbling)
All together create cyclical climate changes?
Sea ice is lost
Abruptly
Positive aspects of loss of sea ice
New trade routs
Loss of sea ice is unlikely to result in sea level
Runaway global warming is
Fed by the thawing and the release of methane gas
Methane gas captures the most energy
What is deformation
The change a rock body undergoes in volume and/shape
what are the types of stress
- Compression-pushing it together
- Tension-pulling it apart
- Shear- pushing together put forces are offset
What are the three types of deformation
- Elastic-temporary and reversible once stress is relieved (think Rubber band)
- Plastic-permanent folding of the rock
- Brittle-permanent fracturing of the rock
as a rock get hotter it becomes more
as a rock get colder it beomes more
hotter it gets becomes or plastic
colder it becomes more brittle
zone of brittle deformation is above the
the zone of plastic deformation (15km)
earthquakes are associated with
brittle deformation (fracture)
what is a fault
a fracture in the earths crust that shows clear displacement of one side relative to the other
what are the types of faults
- Dip-slip faults(vertical offset)
a. normal faults
b. reverse and thrust faults - Strike-slip faults
a. right-lateral
b. left-lateral
Hanging wall and foot wall is associated with
dip-slip faults
HW sits above the fault
FW sits below the fault
how do you know if it is a normal fault
HW moves down in relation to the FW
(caused by tension) common with oceanic ridges
How do you know if it is a reverse fault
HW moves up in relation to the FW
(Caused by compression) common with convergent plate boundaries EX oceanic trenches
how do you know if there is strike fault
you must look from above the ground
how to tell if it is right lateral or left lateral?
if the other side of the fault has moved right it is right lateral
if it has moved left then it is a left lateral
strike-slip faults are associated with
shear stress (transform plate boundaries)
where ever you have a bend in a strike-slip fault
you will always have a localized area of either compression or tension.
how do you know if it is right stepping
if it curves the right (following the line to the right)
An earthquake is
a vibration of the earth produced by rapid release of energy.
The Great San Francisco Earthquake
April 18, 1906
80% of damage was caused by fire (Ham and Eggs Fire)
official death count 700 but 5000 died from indirect result
occurred on the San Andreas Fault
Elastic Rebound theory
it is two sides in constant motion, but offset occurs during earthquake (once it breaks it springs back to original shape)
the motion across the San Andreas fault moves @
6 cm per year (about 2 inches per year)
What is a fault creep
it is where constant motion occurs every year (wont have have earthquakes)
Deep Earthquakes occur
on oceanic trenches
Benioff Zone
is a zone of earthquake activity associated with subduction
the source of the earthquake is
the hypocenter
directly above the hypocenter (source of the earthquake)
the epicenter
how do we record seismic waves
with seismographs
what are the two types of waves
Body waves and surface waves
body waves
travel through the earths interior
1) primary waves
2) secondary waves
Surface waves
They are L-waves (long) that travel along the surface of the earth
1) Raleigh waves
2) love waves
seismic waves are a
form of elastic energy
P-waves definition
a wave of compression and the only wave that changes the volume of the rock as it passes through (all other waves changes the shape of the rock)
Think of slinky example
S-wave definition
they vibrate perpendicular to direction the wave is traveling thus changing the shape of the rock as it passes through (think of rope example)
differences between Rayleghieh waves and Love waves
Rayleigh waves have up and down motion (rotate backwards as they travel forward) and love waves have side to side motion
List the waves from fastest to slowest
the first waves are the P-waves
S-waves
Finally the L-waves (most dangerous)
How locate the epicenter?
- determine the P-S Interval (time between p arrives and S arrives) [greater the interval the farther you are from epicenter]
- Triangulation (must have three pinpoints)
How do we measure earthquakes?
1) intensity- the effect of an earthquake at any given local
[Modified Mercalli Intensity Scale goes from 1-12]
2) Magnitude- earthquake strength
[Magnitude Scale]
Explain the Magnitude Scale
each time you move once on the scale (ex 3 to 4) the ground shaking increases 10 times and energy released in 30 times.
[If it moves up 2M the it would 100 times more shaking and 900 times more energy released]
What are the two measurements to determine magnitude
- P-S interval
2. the amplitude of the S-wave
What do we know about intraplate earthquakes
- they are often large magnitude events
- the probably occur along zones of weekend crust
- the recurrence intervals are usually large (centuries)
ex. New Madrid (1811-1812) Missouri
What are the destructive effects of earthquakes?
- Ground shaking
- Fire
- Tsunami (seismic Sea Waves)
- Land slides
Two key factors to think about in ground shaking
A) Building Design
B) Nature of the Ground material
Best building material for homes
it most be strong and flexible (riding the vibrations out)
ex. wood and steel (frame structure)
What is base shear?
Result from love waves (moving from side to side)
we want to avoid soft first stories
What is resonance?
it is when the building is in sync with the wave period of motion of the seismic wave
the factors are the building heights and the different ground material Ex. tall building with soft ground (worst case scenario)
Soft material for building
is the worst material because it enhances ground vibrations.
when does liquefaction occur?
it occurs with firm ground
- cubic packing (loosely compacted soil)
- during earthquake it becomes hexagonal packing limiting space for water
- water shoots out with tremendous pressure (sand blows) Stuff sink in the ground
how are tsunami’s produced
by a rapid displacement in the water (must be vertical displacement)
tsunami generated by earthquake is called
seismic sea wave
never use tidal wave ever
name the major fault that San Diego should be concerned with?
Rose Canyon Fault
1-2% chance of earthquake occurring within 30 years
example of intraplate earthquake
Libson, Portugal (1755) (and New Madrid)
fire
tsunami
buildings collapsed
example of a subduction earthquake
Alaska (1964)
9.2 magnitude
Landers/Big Bear Earthquake
Lander 7.5 M triggered Big Bear 6.5 M [3 hour separation]
did not occur on san Andreas Fault
Northridge Earthquake
large earthquake under a major metropolitan area
61 people died and $25 billion in damages
-Caused by blind thrust fault
Can we predict Earthquakes?
We can predict where an earthquake
we can make longer term predictions on earthquakes occurring
Our short-term prediction is still in development
BUT other nations have predicted in short term (china)
What are the methods of Earthquake prediction?
1) Locating seismic maps
2) Determining Recurrence intervals
3) Measuring dilatancy
4) observing unusual animal behavior
what are seismic gaps?
area where no significant Earthquake has been recorded because
1) fault creep (constant motion)
2) no motion and stress is building up
recurrence interval is
determining the average length of time between earthquakes of a given magnitude
The stages of dilatency
Stage 1: Micro-crack formation
Stage 2: Dilation (expansion)
Stage 3: Influx of water
Earthquake
How do we measure dilatancy in a rock
ground tilt
Foreshock
Measure electrical conductivity of the rock
measure radon level
What is mass wasting?
the downslope of material under the influence of gravity
landslide
a general term for any rapid for of mass wasting
What are the controls of mass wasting
1)gradient (angle of slope) and stability of the slope
2) water
and obviously gravity
what is the angle of repose?
the measure stability of slope (steepest angle at which material remain stable)
when pore of sediment is filled with water (what happens)
1) added weight
2) lubrication
3) loss of cohesion (little bit of water adds to cohesion)
what do we use to classify the type of mass wasting
- type of material
- type of motion
- Velocity (rate) of motion
Solid bedrock=
non-saturated soil=
water-saturated soil=
Soil and rock=
Rock
Earth
Mud
Debris
A) Fall
B) Slide
C)Flow
A. “free-fall” or “rock fall”
B. intact body that moves down a well defined surface ex slump (going down curve surface)
C. moves down as viscous liquid (not intact) ex. mudflows, earthflows and debris flow
the term for a fast form of mass wasting is
avalanche
the term for the slowest form of mass wasting
hillside creep
What is Asperite
it is a high friction are (stable rough spot)
Associated with periodic fault movement
Gros Ventre, Wyoming [1925]
this was a rock slide in 1925-caused by heavy amount of rainfall (made the rock heavy the layer of clay was made slippery and slide down)
Rock slide created a dam and the water broke out and killed 7 people Kelly, Wyoming
Vaoint Dam, Italy [1963]
Area of susceptible of land slide activity
what contributed to the landslide was
1. rock slipping
2.Limestone on top of a layer of clay
3. Heavy rain made clay slipper (well defined surface)
AFTERMATH: 3000 people died
Yungay, Peru (1970)
this is an example of an avalanche (very rapid motion)
it was trigger by an Earthquake (7.7 M)
killed over 25000 people
92 people survived by climbing cemetery hill
(4 minutes to save themselves)
Mudflows are more common
semi-arid environments ex southern California
Earth flows or more common in
high precipitation
very slow compared to mudflows
