TECTONICS

Question 1

Name the layers of the earth from inside to outside

Answer 1

Inner core, outer core, asthenosphere, lithosphere, crust (oceanic or continental)

Question 2

Describe the features of the inner core

Answer 2

Made of Iron and nickel

~7000 degrees Celsius due to radioactive decay, but solid

Question 3

Describe the outer core

Answer 3

Molten

Question 4

Describe the asthenosphere

Answer 4

Made of magma and is where convection currents occur

Question 5

Why do convection currents occur and what do they do?

Answer 5

Caused by differences in temperature in asthenosphere due to rise and cool of magma

Move tectonics, plate movement direction depends on direction of current

Question 6

Describe the lithosphere

Answer 6

Where tectonic plates are formed, it floats on the asthenosphere

Question 7

Describe oceanic crust

Answer 7

Made of basalt rock, thin and dense

Lines ocean floor

Question 8

Describe continental crust

Answer 8

Made of granite, older and thicker than oceanic but less dense.

Question 9

Describe conservative plate margins

Answer 9

Where 2 plates slide alongside each other

Often result in shallow focus earthquakes e.g San Andreas, California

Question 10

Describe divergent plate boundaries

Answer 10

Where 2 plates move away from each other

Forms new crust
Mid ocean ridge in oceans
Rif valleys on continents

Question 11

What is a riff valley?

Answer 11

Crust stretches and breaks, land between the faults collapses forming riff valleys

E.g East African rift

Question 12

What is an intra-plate earthquake?

Answer 12

When stress in an ancient fault causes it to become active again

Occur in the middle of a plate

E.g Grimsby 2008, 5.2 mag earthquake

Question 13

What are hotspot volcanoes?

Answer 13

Magma plumes erupt onto the seafloor.

As tectonic plates move, the volcano formed is carries away and a new one forms.

Creates chain of Volcanic Islands e.g Hawaii’s 8 islands

Question 14

What is slab pull?

Answer 14

When old, dense heavy plate sinks, pulling plates behind it with it

Question 15

What is slab push?

Answer 15

When magma rises and pushes up plate

Question 16

Describe seafloor spreading

Answer 16

Formation of new crust as plates move apart.

Is evidence for tectonic movement

Question 17

Why is seafloor spreading evidence for tectonic movement?

Answer 17

The further you go form plate boundary, the thicker the sediment

Age of rock increases when you go further from mid-ocean-ridge

Alfred Wegner- Continental drift

Question 18

What is paleomagnatism?

Answer 18

Bands of rock face N/S pole, magnetic reversal about every 400,000yrs…

Rock bands are symmetrical either side of MAR, proves sea floor spreading

Question 19

Describe a P-wave

Answer 19

Fastest wave, travel through liquids and solids
Only damaging in most powerful earthquakes

Question 20

Describe an S wave

Answer 20

Only travel through solids

Greater amplitude than P waves so are more dangerous

Question 21

Describe L-waves

Answer 21

Slower, travel along earths surface

Most destructive waves

Question 22

What is liquification?

Answer 22

Shaking causes surface rocks to loose strength and liquify

Causes building etc to sink.

Question 23

What is a lahar?

Answer 23

Forms when deposited ash mixes with water to create a destructive mudflow

(water comes from melted snow on volcano top or rain)

Question 24

What is a pyroclastic flow?

Answer 24

A dense fast moving flow of solidified lava pieces, ash, hot gasses which burns everything in its path

Question 25

What is a lava flow?

Answer 25

Flow of expelled magma from volcanoes magma chamber

Question 26

What is a jokulhlaups?

Answer 26

Secondary impact of volcano eruption Glacial outburst floods which occur when a volcano erupts under a glacier, melt water floods land E.g E15

Question 27

What is the PAR model?

Answer 27

Pressure and release Analyses factors that effect vulnerability of a population

Question 28

Describe a shield volcano

Answer 28

Effusive, relitavley low risk to people Emit basaltic lave

Question 29

Describe a stratovolcano

Answer 29

Highly explosive, high risk Emit ash, pyroclastic flows etc

Question 30

Describe cinder cone volcanoes

Answer 30

Moderate explosivity, mid risk, short eruptions Emit pyroclastic flows and tephra

Question 31

What is tephra?

Answer 31

Rock fragments that are ejected by a volcano

Question 32

What is pillow lava?

Answer 32

Happens when lava is released underwater

Question 33

What does Park's model show?

Answer 33

Shows hazard recovery with rough time scale Steepness of curve= how quickly area deteriorates and recovers

Question 34

Name some methods of mitigating tectonic hazards and say whether they're micro or macro and which country used them

Answer 34

MACRO Tsunami flood wall, Japan Exclusion/evacuation zone, Montserrat Spray water onto slow moving lava to solidify it, Iceland (1973) PTWS, Japan MICRO Aseismic buildings, Japan