[Unit 1: Enquiry Question 1]

Question 1

Constructive (divergent) boundary

Answer 1

A plate boundary where two plates move away from each other. Plates move by sea floor spreading. magma rises from mantle creating new crust which pushes the plates further apart.

DRC on boundary, mt nyiragongo

Question 2

Collision plate boundary

Answer 2

A plate boundary where two (continental & continental) plates move toward each other, neither can subduct. so they both crumple and form mountains (e.g. Himalayas)

Question 3

destructive boundary

Answer 3

A plate boundary where two (oceanic & continental OR oceanic & oceanic) plates move toward each other, the more dense one subducts. Moves via slab pull

cause deep ocean trench, fold mountains, earthquakes (tsunamis).

Question 4

Conservative boundary

Answer 4

Where two tectonic plates slide past each other, but where crust is neither formed or destroyed. earthquakes form from the friction build up (e.g. San Andres Fault)

Question 5

Intra-plate earthquakes

Answer 5

These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes. ancient fault lines are reactivated forming seismic waves. Some may form new plate boundaries. weakened crust cracks under pressure

Question 6

Intra-plate volcanoes

Answer 6

formed at hotspots, this is fed by a mantle plume which is an area with really hot and low density magma. This breaks through the crust and forms a volcano

Question 7

Slab Pull

Answer 7

the pulling of a tectonic plate as its edge subducts deep into the mantle. denser oceanic plates subduct at cold downwellings. This causes cooler mantle areas. affecting convection

Question 8

Oceanic Crust

Answer 8

7km deep. 28-400°C. low. Basalt. Solid

Question 9

Continental crust

Answer 9

70km thick. 28-400°C. low. Granite. Solid.

Question 10

Mantle

Answer 10

700-2890km thick. 870°C. medium. Peridotite. Solid & liquid layers

Question 11

Outer Core

Answer 11

2890-5150km thick. 4400-6100°C. dense. Iron (mainly) and sulphur. Liquid generating magnetic field.

Question 12

Inner Core

Answer 12

5150km-centre. 7000°C (radioactive decay). very dense. Iron (mainly) & nickel. Solid

Question 13

Structure of the Earth (Chemical & Physical layers)

Answer 13

Oceanic crust (basalt)
Continental crust (granite)
Mantle (Peridotite)

Lithosphere - crust + upper mantle
Asthenosphere - upper mantle
mesosphere - (lower) mantle

Question 14

How do plates move (divergent boundary)?

Answer 14

divergent plate boundaries - the crust thins as it is pulled apart, mantle rises to fill gap. This creates new seafloor. This new seafloor pushes the plates apart on either side.

Question 15

How do plates move (destructive boundary)?

Answer 15

the less dense plate subducts into the mantle.
the older/cooler rock pulls the plate into the mantle behind it
(slab pull)

Question 16

what discovery was made for tectonics in 1915

Answer 16

Alfred Wegner - theory of continental drift.
-fossils oceans apart (same green plants) on all continents (once all had same climate)
-mountain ranges have similar rock types. Pangea lines them up as one big mountain range
-What causes continents to move? Scientists mocked it.

Question 17

what discovery was made for tectonics in 1918

Answer 17

Sonar tech developed.

Map ocean floor (thought it was flat at first)

They were now aware of crust under ocean (ocean floor move)

Belief isn’t credible but gaining support

Question 18

what discovery was made for tectonics in 1919

Answer 18

Arthur Holmes - suggests convection currents in mantle

-upwards ruptures surface

-downwards causes buoyant continents to crumple into mountains

-lateral moves surface like conveyor belt

Question 19

what discovery was made for tectonics in 1946

Answer 19

Ocean floor mapped completely.

-mid oceanic ridge

-mountains

-volcanoes

-deep ocean trenches

Question 20

what discovery was made for tectonics in 1954

Answer 20

J.P.Ruthé - Map of volcanic eruptions & earthquake zones

Question 21

what discovery was made for tectonics in 1960

Answer 21

Harry Hess & Robert Dietz - sea floor spreading theory

Question 22

what discovery was made for tectonics in 1963

Answer 22

pattern of magnetic striped rock. Provides evidence for seafloor spread theory.

Question 23

what discovery was made for tectonics in 1965

Answer 23

J.Tunzo Wilson - plate tectonics theory

Question 24

what discovery was made for tectonics in 1983

Answer 24

GPS available for public use to track movement of Earth’s surface.

Question 25

define Earthquake

Answer 25

caused by a sudden movement near to surface along a fault

Question 26

define the Benioff Zone

Answer 26

Area of seismicity corresponding with the slab being thrust downwards in a subduction zone. cause multiple earthquake at once

Question 27

Two types of seismic waves

Answer 27

body waves and surface waves

Question 28

Two types of body waves

Answer 28

P waves and S waves

Question 29

Features of P waves

Answer 29

- Longitudinal - Travel through solids and liquids - Travel faster than S-waves -first waves to come -compress and expand the ground -cause buildings to expand and contract

Question 30

Features of S waves

Answer 30

after P waves vibrate side to side and up and down shake ground back and forth shake buildings cant move through liquids slower than P-Waves

Question 31

What are the two types of surface waves

Answer 31

Love waves and Rayleigh waves

Question 32

features of surface waves

Answer 32

slower more violent Rayleigh: make the ground roll like ocean waves Love: shake from side to side

Question 33

What is primary hazard (and examples)

Answer 33

immediately, direct result of the earthquake e.g crustal fracture and ground shaking

Question 34

What is secondary hazard (and examples)

Answer 34

as a consequence of ground shaking e.g. land slides, soil liquification and tsunamis

Question 35

2011 Tohoku tsunami case study list as many facts as you can

Answer 35

18500 deaths $220 billion damages caused by magnitude 9 earthquake (focus of 24.4km) -pacific plate subducting under Okhotsk plate wave height was 3-40m high hitting at 35km/hr hit Japans low lying east surrounded by deep waters -allowing waves to retain energy as they travelled estuaries funnelled the waves 4.4million left without electricity 7 reactors at fukushima meltdown transport lines damaged

Question 36

what is soil liquification

Answer 36

When loosely packed grains of soil held together by friction get shaken by the earthquake, the soil becomes destabilized, increasing the space between grains. Soil flows like liquid. Causes buildings to tip/sink/collapse

Question 37

What determines the impact of a tsunami

Answer 37

-duration -wave amplitude -physical geography of the coast -coastal ecosystem buffer -timing -coastal development & proximity from coast

Question 38

what is a volcano

Answer 38

extrusive structure found on Earth's surface ranging from gentle fissure eruptions to explosive composite cones.

Question 39

The shape of a volcano is related to its type of lava. What are the 3 main types of lava?

Answer 39

-basaltic -andesitic -rhyolitic

Question 40

give the eruption temp, gas content, viscosity and SiO2 content of all three types of lava

Answer 40

Temp, Gas, Viscosity, SiO2 basaltic: high, low, low, 50% andesitic: mid, mid, mid, 60% rhyolitic: low, high, high, 70%

Question 41

Explosivity depends on: temp, gas, viscosity and SiO2 content. how do each of these impact the explosiveness?

Answer 41

higher temp increases explosion higher gas content increases explosion lower viscosity increases explosion lower SiO2 increases explosion

Question 42

what are pyroclasts

Answer 42

in all explosive eruptions hot fragments projected damage on impact

Question 43

what is tephra

Answer 43

all explosive eruptions collective term: airborne or ground-flowing pyroclasts major destruction over distances

Question 44

what are landslides

Answer 44

disturbing of land by magmatic pressure flows of rocks, mud and tephra destruction of property and land

Question 45

what are poisonous gases

Answer 45

any eruption gases (HCl, CO2, HF, SO2) Toxic (1700 in Cameroon (1986) died of asphyxiation)

Question 46

what are lahars

Answer 46

volcanic mudflow depends on slope and volume triggered by rainfall

Question 47

example of a lahar

Answer 47

columbia: -Armero was buried by lahar in 1985. -6 major valleys -travelled at 60kmhr -50m deep -killed 23000 -buildings swept away and buried

Question 48

What is a jokulhlaup

Answer 48

glacial outburst flood causes erosion and deposition large volumes of water caused by failure of ice dam

Question 49

example of jokulhlaup

Answer 49

Iceland EFJ erupted in 2010, roads damaged, bridges and house washed away towns evacuated. was anticipated though.