Exam 4 Study Guide

b. high wave height in deep water

Which of the following is not true of tsunami? a. very long wavelength b. high wave height in deep water c. very fast moving d. continued flooding after wave crest hits shore

d) Alfred Wegener

______________________________ was the first to put together all the lines of evidence pointing to a dynamic Earth. a) Bishop Ussher b) James Hutton c) Charles Darwin d) Alfred Wegener

the Richter Scale

a magnitude scale that relates amplitude of largest wave measurement to distance from epicenter

Logarithmic scale

a magnitude scale where: 10x increase of wave amplitude = increase of 1 on the Richter scale - and a 32x increase in the amount of energy released.

surface waves Rayleigh waves: rolling motion -Love waves: side-to-side motion

the slowest moving seismic waves that travel through rock layers just at/below the surface

Divergent Boundaries generally normal faults parallel to the rift valley - transform faults in areas where the rift offsets

where shallow, low-magnitude earthquakes that occur in a narrow band around the rift valley

transform boundary

where there is shallow focus, and variable strength

Benioff Zones help to outline the location of a subducting plate

zones of earthquake occurence that begin at oceanic trenches and tilt landward at about 30-60 degrees

c) Pangea

evidence that the Earth's surface has changed over time from reconstructing the supercontinent: a) Gondwana b) Laurasia c) Pangea d) both a and b

c. turbidity currents.

Great masses of sediment-laden water that are pulled downhill by gravity are called a. contour currents. b. bottom currents. c. turbidity currents. d. traction currents

Earthquake Destruction

-Magnitude and proximity to populated areas -Ground motion: intensity and duration of shaking -Ground failure (liquefaction or mass wasting - rock slides and debris flows) -Foreshocks and aftershocks -Fires -Tsunamis Are all examples of

c) involves the sudden release of progressively stored strain in rocks causing movement along a fault.

12) The elastic rebound theory: a) explains folding of rocks. b) explains the behavior of seismic waves. c) involves the sudden release of progressively stored strain in rocks causing movement along a fault. d) none of the above

b. a change in velocity of seismic waves.

15) Seismic refraction is caused by a. seismic waves bending. b. a change in velocity of seismic waves. c. sharp rock boundaries. d. all of the above. e. a and b.

a. Gondwanaland.

19.20) The southern supercontinent is called a. Gondwanaland. b. Pangaea. c. Laurasia. d. Glossopteris

a. tectonic forces are holding a region up out of isostatic equilibrium.

A positive gravity anomaly indicates that a. tectonic forces are holding a region up out of isostatic equilibrium. b. the land is sinking. c. local mass deficiencies exist in the crust. d. all of the preceding.

e. all of the preceding

A positive magnetic anomaly could indicate a. a body of magnetic ore. b. the magnetic field strength is higher than the regional average. c. an intrusion of gabbro. d. the presence of a granitic basement high . e. all of the preceding

intensity scales (modified mercalli scale, useful for classifying historical earthquakes, zones of damage give clues about building stability, soil and bedrock stability)

A scale that measures strength based on damage

Magnitude scales (richter, logarithmic, and moment scales)

A scale that measures the amount of energy released

b. a segment of an active fault where earthquakes have not occurred for a long time.

A seismic gap is a. the time between large earthquakes. b. a segment of an active fault where earthquakes have not occurred for a long time. c. the center of a plate where earthquakes rarely happen

a. divergent boundaries

A zone of shallow earthquakes along normal faults is typical of a. divergent boundaries b. transform boundaries c. subduction zones d. collisional boundaries

d. oceanic trenches

Benioff zones are found near a. midocean ridges. b. ancient mountain chains. c. interiors of continents. d. oceanic trenches

Seismic Waves

Body waves that travel through the Earth's interior

Earthquakes

Caused when sections of the Earth move past each other along faults

lithosphere

Crust and upper mantle behave as a mechanical unit called the _______________________

b. ophiolites.

Distinctive rock sequences of basalt and marine sedimentary rock that may be slices of the ocean floor are a. guyots. b. ophiolites. c. seamounts. d. fracture zones

confining stresses rupture propagates along the fault

Faults tend to be locked until _________________ are overcome

-Behavior of seismic waves -Gravity data -Magnetic data -Heat flow data -Geology is an integrated science

Geophysics uses physical laws and principles to study ___________ in Earth's interior.

d) both (a) and (b)

Glacial landscapes are formed through: a) erosion of bedrock b) deposition of drift c) variations in Earth's orbit d) both (a) and (b)

b) in the middle of the channel or ice

Glaciers and streams both have their fastest rate of movement: a) along the bottom of their channels or valleys b) in the middle of the channel or ice c) along the edges of their channels or valleys d) during warmer weather

high-density composition -ultramafic rocks (peridotite)

High P-wave velocity (8km/s) indicates ________________

a. lithosphere.

In cross section, the plates are part of a rigid outer shell of the Earth called the a. lithosphere. b. asthenosphere. c. crust. d. mantle

c. deep focus

Most earthquakes at convergent plate boundaries are a. shallow focus b. intermediate focus c. deep focus d. all of the preceding

a. shallow focus.

Most earthquakes at divergent plate boundaries are a. shallow focus. b. intermediate focus. c. deep focus. d. all of the above

c) convergent plate boundaries

Mountain belts are formed in which tectonic setting? a) transform plate boundaries b) divergent plate boundaries c) convergent plate boundaries d) intraplate volcanism

d. all of the preceding.

Oceanic trenches a. are narrow, deep troughs. b. run parallel to the edge of a continent or an island arc. c. are often 8 to 10 kilometers deep. d. all of the preceding.

c. characterized by large negative gravity anomalies.

Oceanic trenches are a. found along a passive continental margin. b. associated with high heat flow. c. characterized by large negative gravity anomalies. d. none of the above.

a. compressional

P waves are a. compressional b. transverse c. tensional

a. divergent plate boundaries.

Passive continental margins are created at a. divergent plate boundaries. b. transform faults. c. convergent plate boundaries

d. all of the preceding

Pelagic sediment could be composed of a. fine-grained clay. b. skeletons of microscopic organisms. c. volcanic ash. d. all of the preceding

b) the existence of benioff zones

Plate tectonics explains: a) cold, dense oceanic crust along mid-ocean ridges b) the existence of benioff zones c) mantle convention d) all of the above

b. barrier reefs.

Reefs parallel to the shore but separated from it by wide, deep lagoons are called a. fringing reefs. b. barrier reefs. c. atolls. d. lagoonal reefs

d. all of the preceding

Which is characteristic of mid-oceanic ridges? a. shallow-focus earthquakes b. high heat flow c. basalt eruptions d. all of the preceding

S-Waves

Shear waves that can only travel through solids

b) a geologically distinct crustal fragment

Terrane refers to a) the topography of an area b) a geologically distinct crustal fragment c) the zone where colliding continents are stuck together d) sediments eroded from uplifting mountains

d) Density; the crust, mantle, and core

The Earth's compositional layers are differentiated by ______________________ and include _______________________. a) How they deform; the lithosphere, athenosphere, and mesosphere (mantle) b) How they deform; the crust, mantle, and core c) Density; the lithosphere asthenosphere, and mesosphere (mantle) d) Density; the crust, mantle, and core

a) How they deform; the lithosphere, athenosphere, and mesosphere (mantle)

The Earth's mechanical layers are differentiated by ______________________ and include _______________________. a) How they deform; the lithosphere, athenosphere, and mesosphere (mantle) b) How they deform; the crust, mantle, and core c) Density; the lithosphere asthenosphere, and mesosphere (mantle) d) Density; the crust, mantle, and core

a) Passive continental boundary

The East Coast of the U.S. is a: a) Passive continental boundary b) transform plate boundary c) divergent plate boundary d) convergent plate boundary

c. mantle plumes.

The Hawaiian Islands are thought to be the result of a. subduction. b. midocean ridge volcanics. c. mantle plumes. d. ocean-ocean convergence

b. magnitude.

The Richter scale measures a. intensity. b. magnitude. c. damage and destruction caused by the earthquake. d. the number of people killed by the earthquake

c. the outer core is fluid.

The S-wave shadow zone is evidence that a. the core is made of iron and nickel. b. the inner core is solid. c. the outer core is fluid. d. the mantle behaves as ductile material

c. transform fault.

The San Andreas fault in California is a a. normal fault. b. reverse fault. c. transform fault. d. thrust fault

b. seafloor magnetic anomalies.

The Vine-Matthews hypothesis explains the origin of a. polar wandering. b. seafloor magnetic anomalies. c. continental drift. d. mid-oceanic ridges

c. Mohorovi˘ ci´c discontinuity.

The boundary that separates the crust from the mantle is called the a. lithosphere. b. asthenosphere. c. Mohorovi˘ ci´c discontinuity. d. none of the preceding

d. iron

The core is probably composed mainly of a. silicon. b. sulfur. c. oxygen. d. iron

a) younger

The higher mountains are, the ________________ they most likely are. a) younger b) older c) more mafic d) more felsic

c) 7

The lithosphere is broken into _______________ major plates a) 3 b) 4 c) 7 d) 11

First Motion (on graph) -push is a positive slope -pull is a negative slope

The motion in seismology that determines direction of motion along a fault and is easiest with faults that have a visible surface component

a. focus

The point within Earth where seismic waves originate is called the a. focus b. epicenter. c. fault scarp d. fold.

c) continental drift

The precursor to modern plate tectonic theory is: a) the paleomagnetic time scale b) seismology c) continental drift d) geophysics

b. isostasy.

The principle of continents being in a buoyant equilibrium is called a. subsidence. b. isostasy. c. convection. d. rebound

c. subduction.

The sliding of oceanic lithosphere beneath a continent or island arc is called a. rotation. b. tension. c. subduction. d. polar wandering.

d. All of the preceding

Which is true of the continental shelf? a. It is a shallow submarine platform at the edge of a continent. b. It inclines very gently seaward. c. It can vary in width. d. All of the preceding

b. magnetic reversals

Which of the following is not an example of the effects of isostasy? a. deep mountain roots b. magnetic reversals c. the postglacial rise of northeastern North America d. mountain ranges at subduction zones

a) oceanic lithosphere subducts under oceanic lithosphere

Volcanic arcs form when: a) oceanic lithosphere subducts under oceanic lithosphere b) oceanic lithosphere subducts under continental lithosphere c) continental crust collides with continental crust d) both a and b

c. 3

What is the minimum number of seismic stations needed to determine the location of the epicenter of an earthquake? a. 1 b. 2 c. 3 d. 5 e. 10

b. continental slope

What part of the continental margin marks the true edge of the continent? a. continental shelf b. continental slope c. continental rise d. abyssal plain

the Mohorovecic discontinuity -marks increase in P-wave velocity by .5 to 1 km/s

What separates the crust from the mantle?

b. suture zone

What would you most expect to find at continent-continent convergence? a. magmatic arc b. suture zone c. island arc d. midocean ridge

a. magmatic arc

What would you most expect to find at ocean-continent convergence? a. magmatic arc b. suture zone c. island arc d. midocean ridge

b. island arc

What would you most expect to find at ocean-ocean convergence? a. suture zone b. island arc c. midocean ridge d. none of the above

Along plate boundaries

Where do most earthquakes occur?

Intraplate earthquakes

a type of earthquake with old fault zones or zones of weakness

Moment magnitude

a way of measuring earthquakes that is modeled for seismic data and takes local geology into account

Shallow focus

an earthquake distribution focus that is: - 0-70km deep, 85% of quakes here

deep focus

an earthquake distribution focus that is: - 350-670km deep, 3% of quakes

intermediate focus

an earthquake distribution focus that is: - 70-350km deep, 12% of quakes

Convergent Boundaries

boundaries that consist of -collision boundaries: generally shallow focus, variable strength -subduction zones: shallow to deep focus; can be very strong

Tsunami (Detection systems?)

caused by earthquakes; high velocity, low amplitude, long wavelength

P-Waves

compression waves that are first detected, have the highest velocity, and can travel through solids, liquids, and gases

the Circum-Pacific belt

contains 80% of shallow/90% intermediate/~100% of deep-focus quakes

continental crust: -30-50 km thick -less dense -slower P-wave -generally felsic igneous/metamorphic rocks overlain by sedimentary rocks oceanic crust: -7 km thick -more dense -faster P-wave -basalt and gabbro - mafic composition

how do continental and oceanic crust differ?