Earthquakes 1

Question 1

What is an Earthquake?

Answer 1

Ground shaking, caused by seismic waves moving through the earth
- many sources but we only worry about the big ones
- scale can go negative

Question 2

___ are responsible for most EQs we care about

Answer 2

Earth’s layers

Question 3

Name the three components of the Earth

Answer 3

1. Crust
2. Mantle
3. Core

Question 4

What is the crust

Answer 4

top part
cold
up to 100km thick

Question 5

What is the mantle

Answer 5

middle part
warmer
- narrow range in compositio
- includes the asthenosphere and parts of lithosphere

Question 6

What is the core

Answer 6

centre part
hot
- metallic iron/nickel
- outer core is liquid
- inner core is solid

Question 7

Tectonic plates are made of

Answer 7

solid crust and upper part of mantle

Question 8

Where are tectonic plates and what do they consist of?

Answer 8

in the lithosphere
- solid crust and upper part of mantle

Question 9

The lithosphere is the

Answer 9

solid crust and upper part of mantle

Question 10

Alfred Lothar Wegner came up with

Answer 10

the Theory of continental drift
- continents were once together and drifted through the oceans

Question 11

True or False: each tectonic plate movement depends on that of others

Answer 11

False
plates move independently of the others
- they move relative to each other

Question 12

The speed of plate tectonics

Answer 12

slow, about as fast as a fingernail grows
(units are in mm/year)

• significant motion take a long time

Question 13

Unifying theory of earth dynamics

Answer 13

Plate Tectonics

• controls how our planet functions
• direct cause of earthquakes, volcanoes, tsunamis, landslides
• responsible for continents, mountain belts, ocean basins, islands
• etc!

Question 14

Continental positions influence

Answer 14

• winds and currents, climate
• evolution!

Question 15

almost all earthquakes occur ___

Answer 15

near plate boundaries

Question 16

Plate tectonics are controlled by

Answer 16

Physical properties
- composition, density, temp

Energy
- gravity, heat

Question 17

Plate tectonics does not work unless

Answer 17

the earth is layered

Question 18

Stratification or layering is caused by

Answer 18

differences in density

Question 19

The crust ___ on the mantle

Answer 19

FLOATS

Question 20

density increases with ___

Answer 20

depth

Question 21

Phase changes are controlled by?

Answer 21

temperature AND pressure

Question 22

Rheology

Answer 22

how a material deforms

Question 23

How does a solid material respond when put under stress?

Answer 23

by deforming (undergoing strain)

Question 24

What are the types of deformation

Answer 24

Elastic
- springs back and reversible

Ductile
- plastic flow
- permanent

Brittle
- breaks
- permanent

Question 25

Rheology is controlled by

Answer 25

- temperature - speed of deformation - duration of deformation

Question 26

T or F: solid material can be all three types of deformation

Answer 26

T

Question 27

The mantle is mostly what phase?

Answer 27

solid - rock that flows cuz high temp - ductile deformation, not melting i.e. viscous flow of a solid

Question 28

Describe the Lithosphere

Answer 28

- consist of crust and uppermost mantle - cool, solid, exterior shell - brittle (sometimes ductile)

Question 29

Describe the Asthenosphere

Answer 29

- the mantle - hotter - SOLID but almost melting - super ductile (geological time)

Question 30

Describe the mesosphere

Answer 30

- lower mantle - even hotter but very high pressure - SOLID and stiff - ductile (geological time)

Question 31

Describe the outer core

Answer 31

- metallic - super hot liquid - extremely high pressure

Question 32

Describe the inner core

Answer 32

- metallic - hotter and higher pressure!! - solid

Question 33

The plates are the ___ (sphere)

Answer 33

lithosphere -> it's broken into plates that move around on top of asthenosphere -> strong, cool, brittle, fractured shell

Question 34

___ plates are thinner and more dense than ____ plates

Answer 34

Oceanic // continental

Question 35

Describe convection cycle of the mantle

Answer 35

<< refer to slides >> - lithosphere forms from hot rising magma - cools as it spreads, then sinks - gravity also pulls cool, dense plate down

Question 36

In earth's convection cycle, what gets recycled?

Answer 36

oceanic lithosphere

Question 37

Why do continents "float"?

Answer 37

- plate tectonics is top of huge ductile convection cycle - mantle & oceanic crust convecting - low density continental crust floats