1: Earthquakes

Question 1

Divergent Tectonic Settings

Answer 1

Tensile (pull-apart) stress produces normal faults.

Question 2

Convergent Tectonic Settings

Answer 2

Compressional Stress produces reverse (thrust) faults.

Question 3

Transform Tectonic Settings

Answer 3

Sheer stress produces strike-slip faults (sliding pass each other)

Question 4

Surface rupture

Answer 4

Forms fault scarp - amount of slip on fault

Question 5

Epicenter

Answer 5

Point on surface above focus

Question 6

Focus

Answer 6

When rupture on fault plane started

Question 7

Body Waves

Answer 7

Travel through the interior of the Earth in all directions from the focus. Includes P and S waves.

Question 8

P-Waves

Answer 8

• Primary
• Fastest wave (4-6 km/sec in hard rock)
• Compressional
  
  • How the waves are transmitted
  • Push-Pull like a slinky

Question 9

S-Waves

Answer 9

• Secondary
• 2/3 the velocity of P-waves
• Shear (S stands for)
  - Not push-pull, more shear
  - Cannot travel through the outer core.

Question 10

Surface Waves

Answer 10

• Travel on the surface of the Earth outward from the epicenter
• Slower than body waves
  
  • Traveling through harder/less dense things
• responsible for damage to structures
  
  • Body waves don’t do a lot of damage.

Question 11

Rayleigh (R) Waves

Answer 11

• Elliptical up and down motion (like water ripples)

Question 12

Love Waves

Answer 12

Horizontal side to side motion (snake up your body)

Question 13

Amplification of Surface Waves

Answer 13

Waves slow down from high density to low density material resulting in increased amplification.

Question 14

Mercalli Intensity Scale

Answer 14

• measures intensity of ground shaking (I-XII)
• based on type of damage and accounts of observers
• Ex. Chicago feels it harder because it is on softer sedimentary rock, while W. Virginia is on hard rock and feels it less.

Question 15

Richter magnitude

Answer 15

• Determined from seismograph measurements
• a better measure of the size of the earthquake at the focus (instead of somewhere further away) based on
  
  • The largest body wave amplification (usually the S-wave) measured at the seismometer.
  • Distance the seismometer is from the epicenter

Question 16

Locating the epicenter of an earthquake

Answer 16

• The further you are from the epicenter the further the p-wave will be from the s-wave.
  - They create a circle around the station based on the P/S-wave lag time.
• Keep doing this at multiple stations until you get a sole intersection of your circles between them all.

Question 17

Seismic hazards

Answer 17

• shaking and ground rupture
• liquefaction
• landslides
• fires
• disease
• tsunami

Question 18

Earthquake prediction (short term)

Answer 18

• sometimes earthquakes are preceded by natural precursors such as foreshocks, low-frequency radio waves, weird animal behavior, etc

Question 19

Earthquake prediction (long term)

Answer 19

• Involves the assessment of the probability of an earthquake of a certain magnitude occuring along a particular fault over a period of time.

Question 20

Long Term: different segments of ___ may have different levels of _____ based on previous history of____

Answer 20

fault; hazard; movement

recent movement = lower hazard

Question 21

% of being hit if living in cali?

Answer 21

62%