Geology 100 - Exam 3

Front 1

Which earthquake did more damage Kobe or Northridge and why?

Back 1

Kobe because earthquake epicenter hit main populated city

Front 2

What are the causes of earthquakes?

Back 2

-release of strain in rocks along fault
-most associated with plate tectonic movement
-point of rupture or shift marks focus

Front 3

What is the epicenter?

Back 3

point on earth's surface above focus

Front 4

True or false: Most earthquakes are followed by aftershocks as rocks continue to move.

Back 4

True

Front 5

What are seismic waves?

Back 5

-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear

Front 6

What type of motion do shear waves create and are they faster or slower than p waves?

Back 6

back and forth; half the speed of p waves

Front 7

Can s waves be transmitted through a liquid?

Back 7

no

Front 8

What is a basic seismometer?

Back 8

weight hangs free in space while drum which is attaced to rock moves within earthquake waves

Front 9

What is a moern seismometers?

Back 9

use earth geophones that can detect very small movements as well as large

Front 10

What are the scales used to describe intensity of movement from earthquakes?

Back 10

-mercalli (I-XII scale)
-richter
-moment-magnitude

Front 11

Which earthquake did more damage Kobe or Northridge and why?

Back 11

Kobe because earthquake epicenter hit main populated city

Front 12

What are the causes of earthquakes?

Back 12

-release of strain in rocks along fault
-most associated with plate tectonic movement
-point of rupture or shift marks focus

Front 13

What is the epicenter?

Back 13

point on earth's surface above focus

Front 14

True or false: Most earthquakes are followed by aftershocks as rocks continue to move.

Back 14

True

Front 15

What are seismic waves?

Back 15

-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear

Front 16

What type of motion do shear waves create and are they faster or slower than p waves?

Back 16

back and forth; half the speed of p waves

Front 17

Can s waves be transmitted through a liquid?

Back 17

no

Front 18

What is a basic seismometer?

Back 18

weight hangs free in space while drum which is attaced to rock moves within earthquake waves

Front 19

What is a moern seismometers?

Back 19

use earth geophones that can detect very small movements as well as large

Front 20

What are the scales used to describe intensity of movement from earthquakes?

Back 20

-mercalli (I-XII scale)
-richter
-moment-magnitude

Front 21

Which earthquake did more damage Kobe or Northridge and why?

Back 21

Kobe because earthquake epicenter hit main populated city

Front 22

What are the causes of earthquakes?

Back 22

-release of strain in rocks along fault
-most associated with plate tectonic movement
-point of rupture or shift marks focus

Front 23

What is the epicenter?

Back 23

point on earth's surface above focus

Front 24

True or false: Most earthquakes are followed by aftershocks as rocks continue to move.

Back 24

True

Front 25

What are seismic waves?

Back 25

-transmission of energy form earthquake through rock in wave form
-body waves - "P" waves for primary and "S" waves for shear

Front 26

What type of motion do shear waves create and are they faster or slower than p waves?

Back 26

back and forth; half the speed of p waves

Front 27

Can s waves be transmitted through a liquid?

Back 27

no

Front 28

What is a basic seismometer?

Back 28

weight hangs free in space while drum which is attaced to rock moves within earthquake waves

Front 29

What is a moern seismometers?

Back 29

use earth geophones that can detect very small movements as well as large

Front 30

What are the scales used to describe intensity of movement from earthquakes?

Back 30

-mercalli (I-XII scale)
-richter
-moment-magnitude

Front 31

What is the moment-magnitude scale more suited to measure?

Back 31

energy released rather than effect which can vary depending on rock thru which waves are passing (-2 to 10 scale)

Front 32

What scale are most earthquakes reported in popular press as?

Back 32

richter scale (1.0 to 8.0 scale) - not a linear scale (4.0 is not twice as strong as 2.0)

Front 33

What have advances in earthquake detection and measurements been driven by?

Back 33

need to monitor for nuclear tests

Front 34

What caused most of the damage in the 1906 San Francisco earthquake? and how much movement did it cause?

Back 34

-fires
-7 meters or 25 feet

Front 35

What earthquake in 1989 represented movement on the San Andreas Fault zone south of san francisco?

Back 35

Loma-Prieta Earthquake

Front 36

What is liquefaction?

Back 36

occurs when the grains in a layer of wet, fine-grained sediment shake during an earthquake. (in 1964, the clay layer beneath the entire Turnagain Heights area of Anchorage, Alaska, liquefied, resulting in a chaotic landscape of jumbled homes and asphalt blocks)

Front 37

Where are the world's priniciple earthquake zones?

Back 37

-plate boundaries
-80% energy in Pacific Rim region
-depth dependent on type of plate boundary
-shallow-rift and continental plate
-deep subduction
-intraplate
-generally less energy
-exceptions- New Madrid and 1998 ocean floor south of Australia
-generally shallow (why? - not known - old faults, unloading?)

Front 38

What type of foci are associated with divergent zones?

Back 38

shallow earthquake foci

Front 39

What type of foci are associated with subduction zones?

Back 39

progressively deeper earthquake foci

Front 40

What type of foci are associated with continental collision zones?

Back 40

shallow earthquake foci

Front 41

What type of foci are associated with intraplate continental rift zones?

Back 41

shallow earthquake foci

Front 42

What type of foci are associated with transform boundaries?

Back 42

shallow earthquake foci

Front 43

What are seismic gaps?

Back 43

no activity happens here, even though it is in a prime area

Front 44

Describe tsunami/ tidal waves.

Back 44

-at sea barely perceptible
-crests 100 miles apart
-velocities of 800 km or 500 miles/hour
-crest heights less than 1 meter
-dramatic effects on reaching shore

Front 45

What are the long-term factors for earthquake predictions?

Back 45

-periodicity
-seismic gaps
-rate of movement of plates
-movement builds up stress

Front 46

What are the short-term factors for earthquake predictions?

Back 46

-cracking or distancy - foreshocks
-change in seismic V
-water level changes
-electrical conductivity
-animal activity

Front 47

True or false earthquake prediction is just as good as volcanic eruptions.

Back 47

False

Front 48

What are some things plate tectonics determine?

Back 48

-climate by controlling distribution of land masses and their latitudes
-location of landmasses determines oceanic circulation
-mountains block and direct air mass movement
-volcanic activity produced the N that makes up 80% of our atmosphere and released water vapor that condensed to contribute to our oceans

Front 49

What does Earth's lithosphere consist of?

Back 49

60 miles in thickness of rigid plates

Front 50

True or false: Center of plates tend to be geologically stable.

Back 50

True

Front 51

True or false: Fossils, rocks, and climates match across continents where they were once joined.

Back 51

True

Front 52

What did magnetometers towed by ships detect?

Back 52

changes in strength of Earth's magnetic field. plotting of these changes showed stripes of weaker and stronger fields
-early 1960's Vine and Drummond proposed stripes represent evidence of searfloor spreading at mid-ocean ridges

Front 53

What happens as basalt cools?

Back 53

its crystallizing magnetic minerals line up with current Earth's magnetic field

Front 54

What does dating basalt in given stripe yield?

Back 54

rates of movement

Front 55

What plates move the fastest each year?

Back 55

pacific, nazca, cocos, and australian-indian plates

Front 56

What are the slowest moving plates?

Back 56

north and south america, eurasian, and antarctic

Front 57

What all have refined view of the ocean bottom?

Back 57

-deep diving submersides
-ocean drilling
-gravitational measurements by satellites
-sonar imaging

Front 58

What are the 3 mechanisms for oceanic plate movement?

Back 58

-ridge push
-slab pull
-plate sliding

Front 59

What is ridge push?

Back 59

rising magma at divergent plate boundaries push plates apart

Front 60

What is slab pull?

Back 60

subducting lithosphere becomes more dense as felsic components rise due to partial melting, causing it to sink and pull plates sideways

Front 61

What is plate sliding?

Back 61

lithosphere of subducting plate sides down slope created by elevated mid-ocean ridge ("convention current" - helps pull apart and collide)

Front 62

What is convention current?

Back 62

helps pull apart and collide

Front 63

What are the ores folded in mountain rocks (mid-ocean ridges)?

Back 63

Cu, Fe, Zn, Co, Ag, Cd

Front 64

What are "black smokers"? (mid-ocean ridges)

Back 64

-consist of hot plumes of mineral-rich water vented at volcanically active regions of seafloor
-accumulations of precipitated minerals form chimney-like structures - "smoke" - consists of hot water and particles of iron
-bacteria can form around hydrothermal vents derive energy from heat generated chemical reactions

Front 65

Why do the Himalayas have no volcanoes?

Back 65

one plate is not subducting

Front 66

What are the basic components of continents?

Back 66

shields (haven't changed in billion years), continental platform (thin veneer of younger sedimentary rock), together form craton

Front 67

What happens because continental rock (less dense) doesn't subduct?

Back 67

once formed becomes permanent part of Earth's crust

Front 68

Describe plate tectonics.

Back 68

-full-fledged theory
-"mountains of evidence"
-most straight forward answer is probably the right answer

Front 69

What are the 3 types of plate boundaries?

Back 69

-divergent
-convergent
-transform