Unit 14

Question 1

Plate tectonics & earthquakes

Answer 1

•Continents seem fixed from human perspective. Until the mid-twentieth century, scientists believed Earth’s continents were rigid

Question 2

Continental Drift

Answer 2

continents move on Earth’s surface; Alfred Wegener proposed this idea in 1912; Pangaea

Question 3

Plate Tectonics

Answer 3

Theory behind motion of lithospheric plates; plates float on the ATHENOSPHERE
(get tectonic plates image form slides)

Question 4

Convection

Answer 4

transfer of heat through a fluid; the asthenosphere bubbles up and encounters the crust which leads it to fracture the crust.

Question 5

mid-oceanic ridges

Answer 5

formed by magma rising up from mantle

Question 6

sea floor separates

Answer 6

new basaltic crust created

Question 7

ocean trenches

Answer 7

sea floor comes together; older lithosphere descends into the asthenosphere where it is recycled

Question 8

Plate Boundaries

Answer 8

the border between two plates

Question 9

Divergent

Answer 9

moving away from each other; constructive; mid-oceanic ridge; youngest crust

Question 10

Convergent

Answer 10

moving towards each other; destructive; collisions

Question 11

oceanic-continental (destructive)

Answer 11

A) oceanic plates sink since it is more dense
B) forms oceanic trench and continental mountains (cascades &Andes)
C) earthquakes occur along margin
D) volcano formation along the plates (continental volcanic arc)
E) forms metamorphic rocks-blueschist

Question 12

oceanic-oceanic (destructive)

Answer 12

A) subduction results in undersea trench formation
B) deep and shallow earthquakes
C) island volcanic arc

Question 13

continental-continental

Answer 13

A) no subduction since two plates are highly buoyant
B) builds huge mountain ranges
C) volcanoes are rare
D) shallow earthquakes are relatively common
E) examples: Himalayan mountains

Question 14

Transform (Stripe-slip)

Answer 14

slide against one another; neither creates nor destroys crust; commonly produce shallow earthquakes; San Andreas fault line (right lateral transform boundary)

Question 15

Fault

Answer 15

a crack in the Earth’s surface

Question 16

Earthquakes

Answer 16

The shaking and trembling of the Earth’s surface caused by sudden releases of stress within the crust; can happen near the surface, deep in the crust, or even in the upper mantle
•generate pulses of energy known as seismic waves

Question 17

Body waves

Answer 17

A)p waves: travel faster and can move though any material; can travel through entirety of Earth
B)S Waves: travel slower and can only pass through solid material

Question 18

Surface Waves

Answer 18

waves you feel and shake the surface

•Seismograph

Question 19

Focus

Answer 19

the actual center of the earthquake; source of shaping

Question 20

Epicenter

Answer 20

the point on the Earth’s surface directly above the focus

Question 21

Magnitude

Answer 21

is energy that is actually released, and it is measured by Richter scale (logarithmic), there is only 1 rating per earthquake;1-10

Question 22

Intensity

Answer 22

is the severity of shaping and it is measured by the Mercalli scale; multiple Mercalli ratings (highest at the epicenter) 1-12

Question 23

Tsunamis

Answer 23

• seismic sea wave

* Produced when ocean water is suddenly displaced by movement of the crust in an earthquake or by a large land slide

Question 24

San Francisco Earthquake of 1906

Answer 24

occurred April 18, 7.8 earthquake occurred at 5 am with an 11 on the Mercalli scale; 3000 people died and 80% of san Francisco was destroyed due to the fires